Hydro-mechanical hybrid transmission device and control method thereof

Abstract

A hydro-mechanical hybrid transmission device and a control method thereof, including an input shaft, a split mechanism, a hydraulic transmission assembly, a mechanical transmission assembly, a convergence mechanism, and an output shaft, wherein the input shaft is connected, through the split mechanism, to the hydraulic transmission assembly and the mechanical transmission assembly, wherein the hydraulic transmission assembly and the mechanical transmission assembly are connected in parallel, and the hydraulic transmission assembly and the mechanical transmission assembly are each connected to the output shaft through the convergence mechanism. In the hydro-mechanical hybrid transmission device, planetary gear structures are combined with engagement/disengagement of brakes and clutches, to implement switching of power split and convergence structural forms.

Claims

1. A hydro-mechanical hybrid transmission device, comprising an input shaft, a split mechanism, a hydraulic transmission assembly, a mechanical transmission assembly, a convergence mechanism, and an output shaft, wherein the input shaft is connected, through the split mechanism, to the hydraulic transmission assembly and the mechanical transmission assembly wherein the hydraulic transmission assembly and the mechanical transmission assembly are connected in parallel, and the hydraulic transmission assembly and the mechanical transmission assembly are each connected to the output shaft through the convergence mechanism; the split mechanism comprises a clutch C.sub.3, a split mechanism sun gear, a split mechanism planet carrier, a split mechanism ring gear, and a brake B.sub.1, wherein the clutch C.sub.3 is connected to the split mechanism sun gear and the split mechanism planet carrier, the brake B.sub.1 is connected to the split mechanism ring gear, the input shaft is connected to the split mechanism sun gear, the split mechanism is connected to the hydraulic transmission assembly through the split mechanism ring gear, and the split mechanism is connected to the mechanical transmission assembly through the split mechanism sun gear and the split mechanism planet carrier; the convergence mechanism comprises a brake B.sub.6, a convergence mechanism ring gear, a convergence mechanism planet carrier, a convergence mechanism sun gear, and a clutch C.sub.7, wherein the brake B.sub.6 is connected to the convergence mechanism ring gear, the clutch C.sub.7 is connected to the convergence mechanism planet carrier and the convergence mechanism sun gear, the convergence mechanism is connected to the hydraulic transmission assembly through the convergence mechanism ring gear, the convergence mechanism is connected to the mechanical transmission assembly through the convergence mechanism sun gear, and the convergence mechanism is connected to the output shaft through the convergence mechanism planet carrier and the convergence mechanism sun gear; the hydraulic transmission assembly comprises a hydraulic transmission input clutch C.sub.1, a hydraulic transmission input gear pair, a unidirectional variable pump, a hydraulic pipe, a unidirectional quantitative motor, a reverse gear pair, a hydraulic transmission output gear pair, and a hydraulic transmission output clutch C.sub.2, wherein the unidirectional variable pump is connected to the split mechanism through the hydraulic transmission input gear pair, the hydraulic transmission input clutch C.sub.1 is arranged between the hydraulic transmission input gear pair and the unidirectional variable pump, the unidirectional variable pump is connected to the unidirectional quantitative motor through the hydraulic pipe, the unidirectional quantitative motor is connected to the convergence mechanism sequentially through the hydraulic transmission output gear pair and the reverse gear pair, and the hydraulic transmission output clutch C.sub.2 is arranged between the unidirectional quantitative motor and the hydraulic transmission output gear pair.

2. The hydro-mechanical hybrid transmission device according to claim 1, wherein the mechanical transmission assembly comprises a front-set sun gear, a front-set planet carrier, a front-set ring gear, a rear-set sun gear, a rear-set planet carrier, a rear-set ring gear, a clutch C.sub.4, a clutch C.sub.5, a clutch C.sub.6, a brake B.sub.2, a brake B.sub.3, a brake B.sub.4, a brake B.sub.5, a one-way clutch F.sub.1, a one-way clutch F.sub.2, and a one-way clutch F.sub.3; wherein the front-set sun gear is connected to the split mechanism through the clutch C.sub.5 and the clutch C.sub.6, wherein the clutch C.sub.5 and the clutch C.sub.6 are connected in parallel, the one-way clutch F.sub.1 is arranged between the clutch C.sub.5 and the front-set sun gear, and the one-way clutch F.sub.2 is arranged between the clutch C.sub.6 and the front-set sun gear, the one-way clutch F.sub.1 and the one-way clutch F.sub.2 have opposite power conduction directions, and the front-set sun gear is also connected to the brake B.sub.3; the front-set planet carrier is connected to the split mechanism through the clutch C.sub.4, the brake B.sub.2 is arranged between the front-set planet carrier and the clutch C.sub.4, and the front-set planet carrier is fixedly connected to the rear-set ring gear; the front-set ring gear is connected to the rear-set planet carrier and the convergence mechanism; the rear-set sun gear is connected to the brake B.sub.4 and the brake B.sub.5, wherein the brake B.sub.4 and the brake B.sub.5 are connected in parallel, the one-way clutch F.sub.3 is arranged between the rear-set sun gear and the brake B.sub.5, and a brake direction of the one-way clutch F.sub.3 is a rotation direction of the rear-set sun gear and the rotation direction of the rear-set sun gear is opposite to a rotation direction of the split mechanism planet carrier; the rear-set planet carrier is connected to the front-set ring gear and the convergence mechanism; the rear-set ring gear is connected to the front-set planet carrier and the split mechanism, and the brake B.sub.2 and the clutch C.sub.4 in parallel connection are arranged between the rear-set ring gear and the split mechanism.

3. A control method of the hydro-mechanical hybrid transmission device according to claim 2, wherein three types of transmission in a forward direction, comprising a forward pure hydraulic transmission, a forward hydro-mechanical hybrid transmission, and a forward pure mechanical transmission, and three types of transmission in a reverse direction, comprising a reverse pure hydraulic transmission, a reverse hydro-mechanical hybrid transmission, and a reverse pure mechanical transmission, are implemented through a combination and an engagement/disengagement of the brakes and the clutches; wherein in the forward pure hydraulic transmission, the brake B.sub.2, the hydraulic transmission input clutch C.sub.1, the hydraulic transmission output clutch C.sub.2, the clutch C.sub.4, and the clutch C.sub.7 are engaged, while other brakes and clutches are disengaged; when the brake B.sub.2 and the clutch C.sub.4 are engaged, the split mechanism planet carrier is locked, the split mechanism sun gear and the split mechanism ring gear rotate in opposite directions, and power passes through the input shaft, the split mechanism, the hydraulic transmission assembly, and the convergence mechanism and the power is output from the output shaft; when the clutch C.sub.7 is engaged, the convergence mechanism planet carrier and the convergence mechanism sun gear of the convergence mechanism are interlocked, an entire convergence mechanism rotates, and by an action of the reverse gear pair, the input shaft and the output shaft rotate in a same direction; in the forward pure mechanical transmission, the brake B.sub.1 and the brake B.sub.6 are engaged, while the brake B.sub.2, the brake B.sub.4, the hydraulic transmission input clutch C.sub.1, the hydraulic transmission output clutch C.sub.2, the clutch C.sub.3, and the clutch C.sub.7 are disengaged; the power passes through the input shaft, the split mechanism, the mechanical transmission assembly, and the convergence mechanism and the power is output from the output shaft; when the brake B.sub.1 is engaged, the split mechanism ring gear is locked, and the split mechanism sun gear and the split mechanism planet carrier transmit the power as gear transmission mechanisms; when the brake B.sub.6 is engaged, the convergence mechanism ring gear is locked, and power passes through the convergence mechanism sun gear and the convergence mechanism planet carrier to the output shaft; in the forward hydro-mechanical hybrid transmission, the hydraulic transmission input clutch C.sub.1, the hydraulic transmission output clutch C.sub.2, and the clutch C.sub.7 are engaged, while the brake B.sub.1, the brake B.sub.3, the brake B.sub.5, the brake B.sub.6, the clutch C.sub.3, and the one-way clutch F.sub.3 are disengaged; the power passes through the input shaft to the split mechanism, transmitted by the split mechanism to the hydraulic transmission assembly and the mechanical transmission assembly respectively, then converged by the convergence mechanism, and output from the output shaft; when the clutch C.sub.3 is disengaged, the split mechanism planet carrier transmits a first part of the power from the input shaft to the mechanical transmission assembly, and the split mechanism ring gear transmits a second part of the power from the input shaft to the hydraulic transmission assembly; when the clutch C.sub.7 is engaged, the power in the mechanical transmission assembly passes through the convergence mechanism sun gear and the convergence mechanism planet carrier and is transmitted to the output shaft, the power in the hydraulic transmission assembly passes through the convergence mechanism ring gear and the convergence mechanism planet carrier and is transmitted to the output shaft, and the convergence mechanism planet carrier rotates in the same direction as the input shaft within a set displacement ratio range; in the reverse pure hydraulic transmission, the hydraulic transmission input clutch C.sub.1, the hydraulic transmission output clutch C.sub.2, the clutch C.sub.3, and the clutch C.sub.7 are engaged, while the other brakes and clutches are disengaged; when the clutch C.sub.3 is engaged, the split mechanism sun gear and the split mechanism planet carrier are interlocked, an entire split mechanism rotates, and the power passes through the input shaft, the split mechanism, the hydraulic transmission assembly, and the convergence mechanism and the power is output from the output shaft; when the clutch C.sub.7 is engaged, the convergence mechanism planet carrier and the convergence mechanism sun gear of the convergence mechanism are interlocked, the entire convergence mechanism rotates, and the input shaft and the output shaft rotate in the opposite directions; in the reverse pure mechanical transmission, the brake B.sub.1, the brake B.sub.2, the brake B.sub.6, the clutch C.sub.6, and the one-way clutch F.sub.2 are engaged, while the other brakes and clutches are disengaged; when the brake B.sub.1 is engaged, the split mechanism ring gear is locked, and the power passes through the split mechanism sun gear and the split mechanism planet carrier and the power is transmitted to the mechanical transmission assembly; when the clutch C.sub.6 and the one-way clutch F.sub.2 are engaged, the power in the mechanical transmission assembly sequentially passes through the clutch C.sub.6, the one-way clutch F.sub.2, the front-set sun gear, and the front-set ring gear, and is then transmitted to the convergence mechanism sun gear; when the brake B.sub.6 is engaged, the convergence mechanism ring gear is locked, and the power passes through the convergence mechanism sun gear and the convergence mechanism planet carrier to the output shaft; in the reverse hydro-mechanical hybrid transmission, the hydraulic transmission input clutch C.sub.1, the hydraulic transmission output clutch C.sub.2, and the clutch C.sub.3 are engaged, while the brake B.sub.1, the brake B.sub.3, the brake B.sub.5, the brake B.sub.6, the clutch C.sub.7, and the one-way clutch F.sub.3 are disengaged; the power passes through the input shaft to the split mechanism, transmitted by the split mechanism to the hydraulic transmission assembly and the mechanical transmission assembly respectively, then converged by the convergence mechanism, and output from the output shaft; when the clutch C.sub.3 is engaged, the split mechanism planet carrier transmits the first part of the power from the input shaft to the mechanical transmission assembly, and the split mechanism ring gear transmits the second part of the power from the input shaft to the hydraulic transmission assembly; when the clutch C.sub.7 is disengaged, the power in the mechanical transmission assembly passes through the convergence mechanism sun gear and the convergence mechanism planet carrier and is transmitted to the output shaft, the power in the hydraulic transmission assembly passes through the convergence mechanism ring gear and the convergence mechanism planet carrier and is transmitted to the output shaft, and the convergence mechanism planet carrier rotates in a direction opposite to the input shaft within the set displacement ratio range.

4. The control method of the hydro-mechanical hybrid transmission device according to claim 3, wherein the forward pure mechanical transmission comprises a first mechanical gear, a second mechanical gear, a third mechanical gear, and a fourth mechanical gear, specifically implemented as follows: in the first mechanical gear, the brake B.sub.5, the one-way clutch F.sub.3, the clutch C.sub.6, and the one-way clutch F.sub.2 are engaged, while the brake B.sub.3, the clutch C.sub.4, the clutch C.sub.5, and the one-way clutch F.sub.1 are disengaged; the power sequentially passes through the clutch C.sub.6, the one-way clutch F.sub.2, and the front-set sun gear to the front-set planet carrier, and the power is split at the front-set planet carrier into the front-set ring gear and the rear-set ring gear respectively; the power in the rear-set ring gear passes through the rear-set planet carrier and the power is converged with the power in the front-set ring gear, and the power is then transmitted to the convergence mechanism; when the brake B.sub.5 and the one-way clutch F.sub.3 are engaged, the rear-set sun gear is locked; in the second mechanical gear, the brake B.sub.5, the one-way clutch F.sub.3, and the clutch C.sub.4 are engaged, while the brake B.sub.3, the clutch C.sub.5, the clutch C.sub.6, the one-way clutch F.sub.1, and the one-way clutch F.sub.2 are disengaged; the power sequentially passes through the clutch C.sub.4, the rear-set ring gear, and the rear-set planet carrier, and the power is then transmitted to the convergence mechanism; when the brake B.sub.5 and the one-way clutch F.sub.3 are engaged, the rear-set sun gear is locked; in the third mechanical gear, the brake B.sub.5, the clutch C.sub.4, the clutch C.sub.5, the one-way clutch F.sub.1, and the one-way clutch F.sub.3 are engaged, while the brake B.sub.3, the clutch C.sub.6, and the one-way clutch F.sub.2 are disengaged; the power sequentially passes through the clutch C.sub.4, the front-set planet carrier, and the front-set ring gear, and the power is then transmitted to the convergence mechanism; since the clutch C.sub.5 and the one-way clutch F.sub.1 are engaged, the front-set sun gear is prevented from an overspeed rotation and the front-set sun gear rotates at a speed consistent with the front-set planet carrier, enabling an entire front planetary gear set mechanism to rotate; in the fourth mechanical gear, the brake B.sub.3 and the clutch C.sub.4 are engaged, while the brake B.sub.5, the clutch C.sub.5, the clutch C.sub.6, the one-way clutch F.sub.1, the one-way clutch F.sub.2, and the one-way clutch F.sub.3 are disengaged; the power sequentially passes through the clutch C.sub.4, the front-set planet carrier, and the front-set ring gear, and the power is then transmitted to the convergence mechanism.

5. The control method of the hydro-mechanical hybrid transmission device according to claim 3, wherein the forward hydro-mechanical hybrid transmission comprises a first forward hybrid transmission gear, a second forward hybrid transmission gear, a third forward hybrid transmission gear, and a fourth forward hybrid transmission gear, specifically implemented as follows: in the first forward hybrid gear, the brake B.sub.4, the clutch C.sub.6, and the one-way clutch F.sub.2 are engaged, while the brake B.sub.2, the clutch C.sub.4, the clutch C.sub.5, and the one-way clutch F.sub.1 are disengaged; the power in the mechanical transmission assembly sequentially passes through the clutch C.sub.6, the one-way clutch F.sub.2, and the front-set sun gear to the front-set planet carrier, and the power is split at the front-set planet carrier into the front-set ring gear and the rear-set ring gear respectively; the power in the rear-set ring gear passes through the rear-set planet carrier and the power is converged with the power in the front-set ring gear, and the power is then transmitted to the convergence mechanism; when the brake B.sub.4 is engaged, the rear-set sun gear is locked; in the second forward hybrid gear, the brake B.sub.4 and the clutch C.sub.4 are engaged, while the brake B.sub.2, the clutch C.sub.5, the clutch C.sub.6, the one-way clutch F.sub.1, and the one-way clutch F.sub.2 are disengaged; the power in the mechanical transmission assembly sequentially passes through the clutch C.sub.4, the rear-set ring gear, and the rear-set planet carrier, and the power is then transmitted to the convergence mechanism; in the third forward hybrid gear, the clutch C.sub.4, the clutch C.sub.5, and the one-way clutch F.sub.1 are engaged, while the brake B.sub.2, the brake B.sub.4, the clutch C.sub.6, and the one-way clutch F.sub.2 are disengaged; the power in the mechanical transmission assembly sequentially passes through the clutch C.sub.4, the front-set planet carrier, and the front-set ring gear, and the power is then transmitted to the convergence mechanism; since the clutch C.sub.5 and the one-way clutch F.sub.1 are engaged, the front-set sun gear is prevented from an overspeed rotation and rotates at a speed consistent with the front-set planet carrier, enabling an entire front planetary gear set mechanism to rotate; in the fourth forward hybrid gear, the brake B.sub.2, the clutch C.sub.6, and the one-way clutch F.sub.2 are engaged, while the brake B.sub.4, the clutch C.sub.4, the clutch C.sub.5, and the one-way clutch F.sub.1 are disengaged; the power in the mechanical transmission assembly sequentially passes through the clutch C.sub.6, the one-way clutch F.sub.2, the front-set sun gear, and the front-set ring gear, and the power is then transmitted to the convergence mechanism.

6. The control method of the hydro-mechanical hybrid transmission device according to claim 3, wherein the reverse hydro-mechanical hybrid transmission comprises a first reverse hybrid transmission gear, a second reverse hybrid transmission gear, a third reverse hybrid transmission gear, and a fourth reverse hybrid transmission gear, specifically implemented as follows: in the first reverse hybrid gear, the brake B.sub.4, the clutch C.sub.6, and the one-way clutch F.sub.2 are engaged, while the brake B.sub.2, the clutch C.sub.4, the clutch C.sub.5, and the one-way clutch F.sub.1 are disengaged; the power in the mechanical transmission assembly sequentially passes through the clutch C.sub.6, the one-way clutch F.sub.2, and the front-set sun gear to the front-set planet carrier, and the power is split at the front-set planet carrier into the front-set ring gear and the rear-set ring gear respectively; the power in the rear-set ring gear passes through the rear-set planet carrier and the power is converged with the power in the front-set ring gear, and the power is then transmitted to the convergence mechanism; when the brake B.sub.4 is engaged, the rear-set sun gear is locked; in the second reverse hybrid gear, the brake B.sub.4 and the clutch C.sub.4 are engaged, while the brake B.sub.2, the clutch C.sub.5, the clutch C.sub.6, the one-way clutch F.sub.1, and the one-way clutch F.sub.2 are disengaged; the power in the mechanical transmission assembly sequentially passes through the clutch C.sub.4, the rear-set ring gear, and the rear-set planet carrier, and the power is then transmitted to the convergence mechanism; in the third reverse hybrid gear, the clutch C.sub.4, the clutch C.sub.5, and the one-way clutch F.sub.1 are engaged, while the brake B.sub.2, the brake B.sub.4, the clutch C.sub.6, and the one-way clutch F.sub.2 are disengaged; the power in the mechanical transmission assembly sequentially passes through the clutch C.sub.4, the front-set planet carrier, and the front-set ring gear, and the power is then transmitted to the convergence mechanism; since the clutch C.sub.5 and the one-way clutch F.sub.1 are engaged, the front-set sun gear is prevented from an overspeed rotation and rotates at a speed consistent with the front-set planet carrier, enabling an entire front planetary gear set mechanism to rotate; in the fourth reverse hybrid gear, the brake B.sub.2, the clutch C.sub.6, and the one-way clutch F.sub.2 are engaged, while the brake B.sub.4, the clutch C.sub.4, the clutch C.sub.5, and the one-way clutch F.sub.1 are disengaged; the power in the mechanical transmission assembly sequentially passes through the clutch C.sub.6, the one-way clutch F.sub.2, the front-set sun gear, and the front-set ring gear, and the power is then transmitted to the convergence mechanism.

7. The control method of the hydro-mechanical hybrid transmission device according to claim 5, wherein an online rolling optimization control is implemented by adopting a vehicle predictive control based on a time domain in combination with a dynamic programming; in a prediction region q, a state transition equation of the vehicle predictive control in a hybrid transmission is:
x(k+1)=μ[x(k),u(k)]; wherein μ is a time-discrete system function, x(k+1) is a state variable related to k+1, x(k) is a state variable related to k, and u(k) is a control variable related to k; in the prediction region q, an objective function of minimizing a fuel consumption of a hydro-mechanical hybrid transmission system is: $J_1=\min \underset{t=t\left(k\right)}{\overset{t=t\left(k+q\right)}{.Math.}}{v}_k\left(x_k,u_k\right)\mathrm{\Delta t};$ wherein J.sub.1 is an objective function of a fuel economy when a linear predictive control system is adopted, v.sub.k is a stage indicator of the k.sup.th stage, x.sub.k is a state variable of the k.sup.th stage, u.sub.k is a control variable of the k.sup.th stage, Δt is a time interval, t(k) is a time point of the k.sup.th stage, and t(k+q) is a time point of the (k+q).sup.th stage; in a control region p, a sensing device is adopted for measurement; and in the prediction region q, a GPS/GIS system is adopted for a prediction; a nonlinear predictive control is adopted to control state variables of the hydro-mechanical hybrid transmission system enabling both a power split and a convergence in each power range, constrain control variables, and estimate future states; the objective function of minimizing the fuel consumption of the hybrid transmission system is: $J_2=\min \underset{t=t\left(k\right)}{\overset{t=t\left(k+q\right)}{.Math.}}L\left[x\left(t\right),u\left(t\right)\right];$ wherein J.sub.2 is the objective function of the fuel economy when a nonlinear predictive control system is adopted, and L is an instantaneous fuel consumption function at a time point t.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic structural diagram of the present invention;

(2) FIG. 2 is a table showing engagement/disengagement states of gear-shift components in the present invention;

(3) FIG. 3 is a schematic diagram showing the power flow in a forward pure hydraulic gear in the present invention;

(4) FIG. 4 is a schematic diagram showing the power flow in a reverse pure hydraulic gear in the present invention;

(5) FIG. 5 is a schematic diagram showing the power flow in forward hydro-mechanical hybrid transmission gear-1 in the present invention;

(6) FIG. 6 is a schematic diagram showing the power flow in forward hydro-mechanical hybrid transmission gear-2 in the present invention;

(7) FIG. 7 is a schematic diagram showing the power flow in forward hydro-mechanical hybrid transmission gear-3 in the present invention;

(8) FIG. 8 is a schematic diagram showing the power flow in forward hydro-mechanical hybrid transmission gear-4 in the present invention;

(9) FIG. 9 is a schematic diagram showing the power flow in reverse hydro-mechanical hybrid transmission gear-1 in the present invention;

(10) FIG. 10 is a schematic diagram showing the power flow in reverse hydro-mechanical hybrid transmission gear-2 in the present invention;

(11) FIG. 11 is a schematic diagram showing the power flow in reverse hydro-mechanical hybrid transmission gear-3 in the present invention;

(12) FIG. 12 is a schematic diagram showing the power flow in reverse hydro-mechanical hybrid transmission gear-4 in the present invention;

(13) FIG. 13 is a schematic diagram showing the power flow in forward mechanical gear-1 in the present invention;

(14) FIG. 14 is a schematic diagram showing the power flow in forward mechanical gear-2 in the present invention;

(15) FIG. 15 is a schematic diagram showing the power flow in forward mechanical gear-3 in the present invention;

(16) FIG. 16 is a schematic diagram showing the power flow in forward mechanical gear-4 in the present invention;

(17) FIG. 17 is a schematic diagram showing the power flow in a reverse pure mechanical transmission gear in the present invention;

(18) FIG. 18 is a diagram showing the principle of vehicle predictive control; and

(19) FIG. 19 is a diagram showing the principle of dynamic coordinated control of a hybrid transmission system in a man-machine interaction environment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(20) The present invention is further described below with reference to the accompanying drawings.

(21) As shown in FIG. 1, a hydro-mechanical hybrid transmission device includes an input shaft 1, a split mechanism 2, a hydraulic transmission assembly 3, a mechanical transmission assembly 4, a convergence mechanism 5, and an output shaft 6. The input shaft 1 is connected, through the split mechanism 2, to the hydraulic transmission assembly 3 and the mechanical transmission assembly 4 that are connected in parallel. The hydraulic transmission assembly 3 and the mechanical transmission assembly 4 are each connected to the output shaft 6 through the convergence mechanism 5. The split mechanism 2 includes a clutch C.sub.3 21, a split mechanism sun gear 22, a split mechanism planet carrier 23, a split mechanism ring gear 24, and a brake B.sub.1 25. The clutch C.sub.3 21 is connected to the split mechanism sun gear 22 and the split mechanism planet carrier 23. The brake B.sub.1 25 is connected to the split mechanism ring gear 24. The input shaft 1 is connected to the split mechanism sun gear 22. The split mechanism 2 is connected to the hydraulic transmission assembly 3 through the split mechanism ring gear 24. The split mechanism 2 is connected to the mechanical transmission assembly 4 through the split mechanism sun gear 22 and the split mechanism planet carrier 23.

(22) The convergence mechanism 5 includes a brake B.sub.6 51, a convergence mechanism ring gear 52, a convergence mechanism planet carrier 53, a convergence mechanism sun gear 54, and a clutch C.sub.7 55. The brake B.sub.6 51 is connected to the convergence mechanism ring gear 52. The clutch C.sub.7 55 is connected to the convergence mechanism planet carrier 53 and the convergence mechanism sun gear 54. The convergence mechanism 5 is connected to the hydraulic transmission assembly 3 through the convergence mechanism ring gear 52. The convergence mechanism 5 is connected to the mechanical transmission assembly 4 through the convergence mechanism sun gear 54. The convergence mechanism 5 is connected to the output shaft 6 through the convergence mechanism planet carrier 53 and the convergence mechanism sun gear 54.

(23) The hydraulic transmission assembly 3 includes a hydraulic transmission input clutch C.sub.1 31, a hydraulic transmission input gear pair 32, a unidirectional variable pump 33, a hydraulic pipe 34, a unidirectional quantitative motor 35, a reverse gear pair 36, a hydraulic transmission output gear pair 37, and a hydraulic transmission output clutch C.sub.2 38. The unidirectional variable pump 33 is connected to the split mechanism 2 through the hydraulic transmission input gear pair 32. The hydraulic transmission input clutch C.sub.1 31 is arranged between the hydraulic transmission input gear pair 32 and the unidirectional variable pump 33. The unidirectional variable pump 33 is connected to the unidirectional quantitative motor 35 through the hydraulic pipe 34. The unidirectional quantitative motor 35 is connected to the convergence mechanism 5 sequentially through the hydraulic transmission output gear pair 37 and the reverse gear pair 36. The hydraulic transmission output clutch C.sub.2 38 is arranged between the unidirectional quantitative motor 35 and the hydraulic transmission output gear pair 37.

(24) The mechanical transmission assembly 4 includes a front-set sun gear 41, a front-set planet carrier 42, a front-set ring gear 43, a rear-set sun gear 44, a rear-set planet carrier 45, a rear-set ring gear 46, a clutch C.sub.4 47, a clutch C.sub.5 48, a clutch C.sub.6 49, a brake B.sub.2 410, a brake B.sub.3 411, a brake B.sub.4 412, a brake B.sub.5 413, a one-way clutch F.sub.1 414, a one-way clutch F.sub.2 415, and a one-way clutch F.sub.3 416.

(25) The front-set sun gear 41 is connected to the split mechanism 2 through the clutch C.sub.5 48 and the clutch C.sub.6 49 that are connected in parallel. The one-way clutch F.sub.1 414 is arranged between the clutch C.sub.5 48 and the front-set sun gear 41, and the one-way clutch F.sub.2 415 is arranged between the clutch C.sub.6 49 and the front-set sun gear 41. The one-way clutch F.sub.1 414 and the one-way clutch F.sub.2 415 have opposite power conduction directions. The front-set sun gear 41 is also connected to the brake B.sub.3 411.

(26) The front-set planet carrier 42 is connected to the split mechanism 2 through the clutch C.sub.4 47. The brake B.sub.2 410 is arranged between the front-set planet carrier 42 and the clutch C.sub.4 47. The front-set planet carrier 42 is fixedly connected to the rear-set ring gear 46.

(27) The front-set ring gear 43 is connected to the rear-set planet carrier 45 and the convergence mechanism 5.

(28) The rear-set sun gear 44 is connected to the brake B.sub.4 412 and the brake B.sub.5 413 that are connected in parallel. The one-way clutch F.sub.3 416 is arranged between the rear-set sun gear 44 and the brake B.sub.5 413. The brake direction of the one-way clutch F.sub.3 416 is the rotation direction of the rear-set sun gear 44 and is opposite to the rotation direction of the split mechanism planet carrier 23.

(29) The rear-set planet carrier 45 is connected to the front-set ring gear 43 and the convergence mechanism 5.

(30) The rear-set ring gear 46 is connected to the front-set planet carrier 42 and the split mechanism 2. The brake B.sub.2 410 and the clutch C.sub.4 47 in parallel connection are arranged between the rear-set ring gear 46 and the split mechanism 2.

(31) As shown in FIG. 2 and FIG. 3, in forward pure hydraulic transmission, the brake B.sub.2 410, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, the clutch C.sub.4 47, and the clutch C.sub.7 55 are engaged, while the other brakes and clutches are disengaged. When the brake B.sub.2 410 and the clutch C.sub.4 47 are engaged, the split mechanism planet carrier 23 is locked to become a reverse gear, and power passes through the input shaft 1, the split mechanism 2, the hydraulic transmission assembly 3, and the convergence mechanism 5 and is output from the output shaft 6. When the clutch C.sub.7 55 is engaged, the convergence mechanism planet carrier 53 and the convergence mechanism sun gear 54 of the convergence mechanism 5 are interlocked, the entire convergence mechanism 5 rotates, and by the action of the reverse gear pair 36, the input shaft 1 and the output shaft 6 rotate in the same direction.

(32) The rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(33) $n_o=\frac{e}{k_1{i}_1{i}_2{i}_3}{n}_I$

(34) wherein n.sub.o is the rotation speed of the output shaft 6, n.sub.1 is the rotation speed of the input shaft 1, e is a ratio of the displacement of the variable pump 33 to the displacement of the quantitative motor 35, i.sub.1, i.sub.2, and i.sub.3 are respectively transmission ratios of gears, and k.sub.1 is a split mechanism characteristic parameter,

(35) if k.sub.1=2 and i.sub.1i.sub.2i.sub.3=1,

(36) $n_o=\frac{e}{2}{n}_I;$

(37) when e∈[0,1],

(38) $n_0\in \left[0,\frac{1}{2}\right]n_I.$

(39) As shown in FIG. 2 and FIG. 4, in reverse pure hydraulic transmission, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, the clutch C.sub.3 21, and the clutch C.sub.7 55 are engaged, while the other brakes and clutches are disengaged. When the clutch C.sub.3 21 is engaged, the split mechanism sun gear 22 and the split mechanism planet carrier 23 are interlocked, the entire split mechanism 2 rotates, and power passes through the input shaft 1, the split mechanism 2, the hydraulic transmission assembly 3, and the convergence mechanism 5 and is output from the output shaft 6. When the clutch C.sub.7 55 is engaged, the convergence mechanism planet carrier 53 and the convergence mechanism sun gear 54 of the convergence mechanism 5 are interlocked, and the input shaft 1 and the output shaft 6 rotate in opposite directions.

(40) The rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(41) $n_o=-\frac{e}{i_1{i}_2{i}_3}{n}_I;$

(42) when e∈[0,1], n.sub.0∈[−1, 0]n.sub.1.

(43) As shown in FIG. 2 and FIG. 5, in forward hydro-mechanical hybrid transmission gear-1, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, and the clutch C.sub.7 55 are engaged, while the brake B.sub.1 25, the brake B.sub.3 411, the brake B.sub.5 413, the brake B.sub.6 51, the clutch C.sub.3 21, and the one-way clutch F.sub.3 416 are disengaged. Power passes through the input shaft 1 to the split mechanism 2, transmitted by the split mechanism 2 to the hydraulic transmission assembly 3 and the mechanical transmission assembly 4 respectively, then converged by the convergence mechanism 5, and output from the output shaft 6. When the clutch C.sub.3 21 is disengaged, the split mechanism planet carrier 23 transmits a part of the power from the input shaft 1 to the mechanical transmission assembly 4, and the split mechanism ring gear 24 transmits the other part of the power from the input shaft 1 to the hydraulic transmission assembly 3. When the clutch C.sub.7 55 is engaged, the power in the mechanical transmission assembly 4 passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, the power in the hydraulic transmission assembly 3 passes through the convergence mechanism ring gear 52 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, and the convergence mechanism planet carrier 53 rotates in the same direction as the input shaft 1 within a set displacement ratio range.

(44) The brake B.sub.4 412, the clutch C.sub.6 49, and the one-way clutch F.sub.2 415 are engaged, while the brake B.sub.2 410, the clutch C.sub.4 47, the clutch C.sub.5 48, and the one-way clutch F.sub.1 414 are disengaged. The power in the mechanical transmission assembly 4 sequentially passes through the clutch C.sub.6 49, the one-way clutch F.sub.2 415, and the front-set sun gear 41 to the front-set planet carrier 42, and is split at the front-set planet carrier 42 into the front-set ring gear 43 and the rear-set ring gear 46 respectively. The power in the rear-set ring gear 46 passes through the rear-set planet carrier 45 and is converged with the power in the front-set ring gear 43, and the power is then transmitted to the convergence mechanism 5. When the brake B.sub.4 412 is engaged, the rear-set sun gear 44 is locked.

(45) As shown in FIG. 2 and FIG. 6, in forward hydro-mechanical hybrid transmission gear-2, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, and the clutch C.sub.7 55 are engaged, while the brake B.sub.1 25, the brake B.sub.3 411, the brake B.sub.5 413, the brake B.sub.6 51, the clutch C.sub.3 21, and the one-way clutch F.sub.3 416 are disengaged. Power passes through the input shaft 1 to the split mechanism 2, transmitted by the split mechanism 2 to the hydraulic transmission assembly 3 and the mechanical transmission assembly 4 respectively, then converged by the convergence mechanism 5, and output from the output shaft 6. When the clutch C.sub.3 21 is disengaged, the split mechanism planet carrier 23 transmits a part of the power from the input shaft 1 to the mechanical transmission assembly 4, and the split mechanism ring gear 24 transmits the other part of the power from the input shaft 1 to the hydraulic transmission assembly 3. When the clutch C.sub.7 55 is engaged, the power in the mechanical transmission assembly 4 passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, the power in the hydraulic transmission assembly 3 passes through the convergence mechanism ring gear 52 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, and the convergence mechanism planet carrier 53 rotates in the same direction as the input shaft 1 within a set displacement ratio range.

(46) The brake B.sub.4 412 and the clutch C.sub.4 47 are engaged, while the brake B.sub.2 410, the clutch C.sub.5 48, the clutch C.sub.6 49, the one-way clutch F.sub.1 414, and the one-way clutch F.sub.2 415 are disengaged. The power in the mechanical transmission assembly 4 sequentially passes through the clutch C.sub.4 47, the rear-set ring gear 46, and the rear-set planet carrier 45, and is then transmitted to the convergence mechanism 5.

(47) As shown in FIG. 2 and FIG. 7, in forward hydro-mechanical hybrid transmission gear-3, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, and the clutch C.sub.7 55 are engaged, while the brake B.sub.1 25, the brake B.sub.3 411, the brake B.sub.5 413, the brake B.sub.6 51, the clutch C.sub.3 21, and the one-way clutch F.sub.3 416 are disengaged. Power passes through the input shaft 1 to the split mechanism 2, transmitted by the split mechanism 2 to the hydraulic transmission assembly 3 and the mechanical transmission assembly 4 respectively, then converged by the convergence mechanism 5, and output from the output shaft 6. When the clutch C.sub.3 21 is disengaged, the split mechanism planet carrier 23 transmits a part of the power from the input shaft 1 to the mechanical transmission assembly 4, and the split mechanism ring gear 24 transmits the other part of the power from the input shaft 1 to the hydraulic transmission assembly 3. When the clutch C.sub.7 55 is engaged, the power in the mechanical transmission assembly 4 passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, the power in the hydraulic transmission assembly 3 passes through the convergence mechanism ring gear 52 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, and the convergence mechanism planet carrier 53 rotates in the same direction as the input shaft 1 within a set displacement ratio range.

(48) The clutch C.sub.4 47, the clutch C.sub.5 48, and the one-way clutch F.sub.1 414 are engaged, while the brake B.sub.2 410, the brake B.sub.4 412, the clutch C.sub.6 49, and the one-way clutch F.sub.2 415 are disengaged. The power in the mechanical transmission assembly 4 sequentially passes through the clutch C.sub.4 47, the front-set planet carrier 42, and the front-set ring gear 43, and is then transmitted to the convergence mechanism 5. Since the clutch C.sub.5 48 and the one-way clutch F.sub.1 414 are engaged, the front-set sun gear 41 is prevented from overspeed rotation and rotates at a speed consistent with the front-set planet carrier 42, enabling the entire front planetary gear set mechanism to rotate.

(49) As shown in FIG. 2 and FIG. 8, in forward hydro-mechanical hybrid transmission gear-4, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, and the clutch C.sub.7 55 are engaged, while the brake B.sub.1 25, the brake B.sub.3 411, the brake B.sub.5 413, the brake B.sub.6 51, the clutch C.sub.3 21, and the one-way clutch F.sub.3 416 are disengaged. Power passes through the input shaft 1 to the split mechanism 2, transmitted by the split mechanism 2 to the hydraulic transmission assembly 3 and the mechanical transmission assembly 4 respectively, then converged by the convergence mechanism 5, and output from the output shaft 6. When the clutch C.sub.3 21 is disengaged, the split mechanism planet carrier 23 transmits a part of the power from the input shaft 1 to the mechanical transmission assembly 4, and the split mechanism ring gear 24 transmits the other part of the power from the input shaft 1 to the hydraulic transmission assembly 3. When the clutch C.sub.7 55 is engaged, the power in the mechanical transmission assembly 4 passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, the power in the hydraulic transmission assembly 3 passes through the convergence mechanism ring gear 52 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, and the convergence mechanism planet carrier 53 rotates in the same direction as the input shaft 1 within a set displacement ratio range.

(50) The brake B.sub.2 410, the clutch C.sub.6 49, and the one-way clutch F.sub.2 415 are engaged, while the brake B.sub.4 412, the clutch C.sub.4 47, the clutch C.sub.5 48, and the one-way clutch F.sub.1 414 are disengaged. The power in the mechanical transmission assembly 4 sequentially passes through the clutch C.sub.6 49, the one-way clutch F.sub.2 415, the front-set sun gear 41, and the front-set ring gear 43, and is then transmitted to the convergence mechanism 5.

(51) The forward hydro-mechanical hybrid transmission includes four hydro-mechanical transmission split gears, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(52) $n_0=\frac{n_I}{\left(k_1+1\right)i_m+\frac{k_1{i}_1{i}_2{i}_3}{e}}$

(53) if k.sub.1=2 and i.sub.1i.sub.2i.sub.3=1,

(54) ${\eta }_0=\frac{n_I}{3i_m+\frac{2}{e}},$

(55) wherein i.sub.m is a transmission ratio of the mechanical transmission assembly, i.sub.m1=2.92 is a transmission ratio of the mechanical transmission assembly in mechanical gear-1, i.sub.m2=1.57 is a transmission ratio of the mechanical transmission assembly in mechanical gear-2, i.sub.m3=1.00 is a transmission ratio of the mechanical transmission assembly in mechanical gear-3, and i.sub.m4=−2.38 is a transmission ratio of the mechanical transmission assembly in mechanical gear-4.

(56) In hydro-mechanical transmission split gear-1, i.sub.m1=2.92, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(57) ${\eta }_0=\frac{n_I}{8.76+\frac{2}{e}}$

(58) when e∈[0,1], n.sub.0∈[0,0.093]n.sub.1.

(59) In hydro-mechanical transmission split gear-2, i.sub.m2=1.57, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(60) ${\eta }_0=\frac{n_I}{4.71+\frac{2}{e}}$

(61) when e∈[0,1], n.sub.0∈[0,0.149]n.sub.1.

(62) In hydro-mechanical transmission split gear-3, i.sub.m3=1.00, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(63) 0${\eta }_0=\frac{n_I}{3.00+\frac{2}{e}}$

(64) when e∈[0,1], n.sub.0∈[0,0.200]n.sub.1.

(65) In hydro-mechanical transmission split gear-4, i.sub.m4=−2.38, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(66) ${\eta }_0=\frac{n_I}{-7.14+\frac{2}{e}}$

(67) when e∈[0,0.25], n.sub.0∈[0,1.163]n.sub.1.

(68) As shown in FIG. 2 and FIG. 9, in reverse hydro-mechanical hybrid transmission gear-1, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, and the clutch C.sub.3 21 are engaged, while the brake B.sub.1 25, the brake B.sub.3 411, the brake B.sub.5 413, the brake B.sub.6 51, the clutch C.sub.7 55, and the one-way clutch F.sub.3 416 are disengaged. Power passes through the input shaft 1 to the split mechanism 2, transmitted by the split mechanism 2 to the hydraulic transmission assembly 3 and the mechanical transmission assembly 4 respectively, then converged by the convergence mechanism 5, and output from the output shaft 6. When the clutch C.sub.3 21 is engaged, the split mechanism planet carrier 23 transmits a part of the power from the input shaft 1 to the mechanical transmission assembly 4, and the split mechanism ring gear 24 transmits the other part of the power from the input shaft 1 to the hydraulic transmission assembly 3. When the clutch C.sub.7 55 is disengaged, the power in the mechanical transmission assembly 4 passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, the power in the hydraulic transmission assembly 3 passes through the convergence mechanism ring gear 52 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, and the convergence mechanism planet carrier 53 rotates in a direction opposite to the input shaft 1 within a set displacement ratio range.

(69) The brake B.sub.4 412, the clutch C.sub.6 49, and the one-way clutch F.sub.2 415 are engaged, while the brake B.sub.2 410, the clutch C.sub.4 47, the clutch C.sub.5 48, and the one-way clutch F.sub.1 414 are disengaged. The power in the mechanical transmission assembly 4 sequentially passes through the clutch C.sub.6 49, the one-way clutch F.sub.2 415, and the front-set sun gear 41 to the front-set planet carrier 42, and is split at the front-set planet carrier 42 into the front-set ring gear 43 and the rear-set ring gear 46 respectively. The power in the rear-set ring gear 46 passes through the rear-set planet carrier 45 and is converged with the power in the front-set ring gear 43, and the power is then transmitted to the convergence mechanism 5. When the brake B.sub.4 412 is engaged, the rear-set sun gear 44 is locked.

(70) As shown in FIG. 2 and FIG. 10, in reverse hydro-mechanical hybrid transmission gear-2, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, and the clutch C.sub.3 21 are engaged, while the brake B.sub.1 25, the brake B.sub.3 411, the brake B.sub.5 413, the brake B.sub.6 51, the clutch C.sub.7 55, and the one-way clutch F.sub.3 416 are disengaged. Power passes through the input shaft 1 to the split mechanism 2, transmitted by the split mechanism 2 to the hydraulic transmission assembly 3 and the mechanical transmission assembly 4 respectively, then converged by the convergence mechanism 5, and output from the output shaft 6. When the clutch C.sub.3 21 is engaged, the split mechanism planet carrier 23 transmits a part of the power from the input shaft 1 to the mechanical transmission assembly 4, and the split mechanism ring gear 24 transmits the other part of the power from the input shaft 1 to the hydraulic transmission assembly 3. When the clutch C.sub.7 55 is disengaged, the power in the mechanical transmission assembly 4 passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, the power in the hydraulic transmission assembly 3 passes through the convergence mechanism ring gear 52 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, and the convergence mechanism planet carrier 53 rotates in a direction opposite to the input shaft 1 within a set displacement ratio range.

(71) The brake B.sub.4 412 and the clutch C.sub.4 47 are engaged, while the brake B.sub.2 410, the clutch C.sub.5 48, the clutch C.sub.6 49, the one-way clutch F.sub.1 414, and the one-way clutch F.sub.2 415 are disengaged. The power in the mechanical transmission assembly 4 sequentially passes through the clutch C.sub.4 47, the rear-set ring gear 46, and the rear-set planet carrier 45, and is then transmitted to the convergence mechanism 5.

(72) As shown in FIG. 2 and FIG. 11, in reverse hydro-mechanical hybrid transmission gear-3, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, and the clutch C.sub.3 21 are engaged, while the brake B.sub.1 25, the brake B.sub.3 411, the brake B.sub.5 413, the brake B.sub.6 51, the clutch C.sub.7 55, and the one-way clutch F.sub.3 416 are disengaged. Power passes through the input shaft 1 to the split mechanism 2, transmitted by the split mechanism 2 to the hydraulic transmission assembly 3 and the mechanical transmission assembly 4 respectively, then converged by the convergence mechanism 5, and output from the output shaft 6. When the clutch C.sub.3 21 is engaged, the split mechanism planet carrier 23 transmits a part of the power from the input shaft 1 to the mechanical transmission assembly 4, and the split mechanism ring gear 24 transmits the other part of the power from the input shaft 1 to the hydraulic transmission assembly 3. When the clutch C.sub.7 55 is disengaged, the power in the mechanical transmission assembly 4 passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, the power in the hydraulic transmission assembly 3 passes through the convergence mechanism ring gear 52 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, and the convergence mechanism planet carrier 53 rotates in a direction opposite to the input shaft 1 within a set displacement ratio range.

(73) The clutch C.sub.4 47, the clutch C.sub.5 48, and the one-way clutch F.sub.1 414 are engaged, while the brake B.sub.2 410, the brake B.sub.4 412, the clutch C.sub.6 49, and the one-way clutch F.sub.2 415 are disengaged. The power in the mechanical transmission assembly 4 sequentially passes through the clutch C.sub.4 47, the front-set planet carrier 42, and the front-set ring gear 43, and is then transmitted to the convergence mechanism 5. Since the clutch C.sub.5 48 and the one-way clutch F.sub.1 414 are engaged, the front-set sun gear 41 is prevented from overspeed rotation and rotates at a speed consistent with the front-set planet carrier 42, enabling the entire front planetary gear set mechanism to rotate.

(74) As shown in FIG. 2 and FIG. 12, in reverse hydro-mechanical hybrid transmission gear-4, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, and the clutch C.sub.3 21 are engaged, while the brake B.sub.1 25, the brake B.sub.3 411, the brake B.sub.5 413, the brake B.sub.6 51, the clutch C.sub.7 55, and the one-way clutch F.sub.3 416 are disengaged. Power passes through the input shaft 1 to the split mechanism 2, transmitted by the split mechanism 2 to the hydraulic transmission assembly 3 and the mechanical transmission assembly 4 respectively, then converged by the convergence mechanism 5, and output from the output shaft 6. When the clutch C.sub.3 21 is engaged, the split mechanism planet carrier 23 transmits a part of the power from the input shaft 1 to the mechanical transmission assembly 4, and the split mechanism ring gear 24 transmits the other part of the power from the input shaft 1 to the hydraulic transmission assembly 3. When the clutch C.sub.7 55 is disengaged, the power in the mechanical transmission assembly 4 passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, the power in the hydraulic transmission assembly 3 passes through the convergence mechanism ring gear 52 and the convergence mechanism planet carrier 53 and is transmitted to the output shaft 6, and the convergence mechanism planet carrier 53 rotates in a direction opposite to the input shaft 1 within a set displacement ratio range.

(75) The brake B.sub.2 410, the clutch C.sub.6 49, and the one-way clutch F.sub.2 415 are engaged, while the brake B.sub.4 412, the clutch C.sub.4 47, the clutch C.sub.5 48, and the one-way clutch F.sub.1 414 are disengaged. The power in the mechanical transmission assembly 4 sequentially passes through the clutch C.sub.6 49, the one-way clutch F.sub.2 415, the front-set sun gear 41, and the front-set ring gear 43, and is then transmitted to the convergence mechanism 5.

(76) The reverse hydro-mechanical hybrid transmission includes four hydro-mechanical transmission convergence gears, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(77) $n_0=\frac{\frac{1}{i_m}-k_2\frac{e}{i_1{i}_2{i}_3}}{k_2+1}{n}_I$

(78) wherein k.sub.2 is a convergence mechanism characteristic parameter,

(79) if k.sub.2=2 and i.sub.1i.sub.2i.sub.3=1,

(80) $n_0=\frac{\frac{1}{i_m}-2e}{3}{n}_I.$

(81) In hydro-mechanical transmission convergence gear-1, i.sub.m1=2.92, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(82) $n_0=\frac{0.342-2e}{3}{n}_I$

(83) when e∈[0.171,1], n.sub.0∈[−0.553,0]n.sub.1.

(84) In hydro-mechanical transmission convergence gear-2, i.sub.m2=1.57, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(85) $n_0=\frac{0.637-2e}{3}{n}_I$

(86) when e∈[0.3185,1], n.sub.0∈[−0.454,0]n.sub.1.

(87) In hydro-mechanical transmission convergence gear-3, i.sub.m3=1.00, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(88) $n_0=\frac{1-2e}{3}{n}_I$

(89) when e∈[0.5,1], n.sub.0∈[−0.333,0]n.sub.1.

(90) In hydro-mechanical transmission convergence gear-4, i.sub.m4=−2.38, and the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(91) $n_0=\frac{-0.420-2e}{3}{n}_I$

(92) when e∈[0,1], n.sub.0∈[−0.807, −0.140]n.sub.1.

(93) As shown in FIG. 2 and FIG. 13, in forward pure mechanical transmission gear-1, the brake B.sub.1 25 and the brake B.sub.6 51 are engaged, while the brake B.sub.2 410, the brake B.sub.4 412, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, the clutch C.sub.3 21, and the clutch C.sub.7 55 are disengaged. Power passes through the input shaft 1, the split mechanism 2, the mechanical transmission assembly 4, and the convergence mechanism 5 and is output from the output shaft 6. When the brake B.sub.1 25 is engaged, the split mechanism ring gear 24 is locked, and the entire split mechanism 2 rotates. When the brake B.sub.6 51 is engaged, the convergence mechanism ring gear 52 is locked, and power passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 to the output shaft 6.

(94) The brake B.sub.5 413, the one-way clutch F.sub.3 416, the clutch C.sub.6 49, and the one-way clutch F.sub.2 415 are engaged, while the brake B.sub.3 411, the clutch C.sub.4 47, the clutch C.sub.5 48, and the one-way clutch F.sub.1 414 are disengaged. Power sequentially passes through the clutch C.sub.6 49, the one-way clutch F.sub.2 415, and the front-set sun gear 41 to the front-set planet carrier 42, and is split at the front-set planet carrier 42 into the front-set ring gear 43 and the rear-set ring gear 46 respectively. The power in the rear-set ring gear 46 passes through the rear-set planet carrier 45 and is converged with the power in the front-set ring gear 43, and the power is then transmitted to the convergence mechanism 5. When the brake B.sub.5 413 and the one-way clutch F.sub.3 416 are engaged, the rear-set sun gear 44 is locked.

(95) As shown in FIG. 2 and FIG. 14, in forward pure mechanical transmission gear-2, the brake B.sub.1 25 and the brake B.sub.6 51 are engaged, while the brake B.sub.2 410, the brake B.sub.4 412, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, the clutch C.sub.3 21, and the clutch C.sub.7 55 are disengaged. Power passes through the input shaft 1, the split mechanism 2, the mechanical transmission assembly 4, and the convergence mechanism 5 and is output from the output shaft 6. When the brake B.sub.1 25 is engaged, the split mechanism ring gear 24 is locked, and the entire split mechanism 2 rotates. When the brake B.sub.6 51 is engaged, the convergence mechanism ring gear 52 is locked, and power passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 to the output shaft 6.

(96) The brake B.sub.5 413, the one-way clutch F.sub.3 416, and the clutch C.sub.4 47 are engaged, while the brake B.sub.3 411, the clutch C.sub.5 48, the clutch C.sub.6 49, the one-way clutch F.sub.1 414, and the one-way clutch F.sub.2 415 are disengaged. Power sequentially passes through the clutch C.sub.4 47, the rear-set ring gear 46, and the rear-set planet carrier 45, and is then transmitted to the convergence mechanism 5. When the brake B.sub.5 413 and the one-way clutch F.sub.3 416 are engaged, the rear-set sun gear 44 is locked.

(97) As shown in FIG. 2 and FIG. 15, in forward pure mechanical transmission gear-3, the brake B.sub.1 25 and the brake B.sub.6 51 are engaged, while the brake B.sub.2 410, the brake B.sub.4 412, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, the clutch C.sub.3 21, and the clutch C.sub.7 55 are disengaged. Power passes through the input shaft 1, the split mechanism 2, the mechanical transmission assembly 4, and the convergence mechanism 5 and is output from the output shaft 6. When the brake B.sub.1 25 is engaged, the split mechanism ring gear 24 is locked, and the entire split mechanism 2 rotates. When the brake B.sub.6 51 is engaged, the convergence mechanism ring gear 52 is locked, and power passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 to the output shaft 6.

(98) The brake B.sub.5 413, the clutch C.sub.4 47, the clutch C.sub.5 48, the one-way clutch F.sub.1 414, and the one-way clutch F.sub.3 416 are engaged, while the brake B.sub.3 411, the clutch C.sub.6 49, and the one-way clutch F.sub.2 415 are disengaged. Power sequentially passes through the clutch C.sub.4 47, the front-set planet carrier 42, and the front-set ring gear 43, and is then transmitted to the convergence mechanism 5. Since the clutch C.sub.5 48 and the one-way clutch F.sub.1 414 are engaged, the front-set sun gear 41 is prevented from overspeed rotation and rotates at a speed consistent with the front-set planet carrier 42, enabling the entire front planetary gear set mechanism to rotate.

(99) As shown in FIG. 2 and FIG. 16, in forward pure mechanical transmission gear-4, the brake B.sub.1 25 and the brake B.sub.6 51 are engaged, while the brake B.sub.2 410, the brake B.sub.4 412, the hydraulic transmission input clutch C.sub.1 31, the hydraulic transmission output clutch C.sub.2 38, the clutch C.sub.3 21, and the clutch C.sub.7 55 are disengaged. Power passes through the input shaft 1, the split mechanism 2, the mechanical transmission assembly 4, and the convergence mechanism 5 and is output from the output shaft 6. When the brake B.sub.1 25 is engaged, the split mechanism ring gear 24 is locked, and the entire split mechanism 2 rotates. When the brake B.sub.6 51 is engaged, the convergence mechanism ring gear 52 is locked, and power passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 to the output shaft 6.

(100) The brake B.sub.3 411 and the clutch C.sub.4 47 are engaged, while the brake B.sub.5 413, the clutch C.sub.5 48, the clutch C.sub.6 49, the one-way clutch F.sub.1 414, the one-way clutch F.sub.2 415, and the one-way clutch F.sub.3 416 are disengaged. Power sequentially passes through the clutch C.sub.4 47, the front-set planet carrier 42, and the front-set ring gear 43, and is then transmitted to the convergence mechanism 5.

(101) As shown in FIG. 2 and FIG. 17, in reverse pure mechanical transmission, the brake B.sub.1 25, the brake B.sub.2 410, the brake B.sub.6 51, the clutch C.sub.6 49, and the one-way clutch F.sub.2 415 are engaged, while the other brakes and clutches are disengaged. When the brake B.sub.1 25 is engaged, the split mechanism ring gear 24 is locked, and power passes through the split mechanism sun gear 22 and the split mechanism planet carrier 23 and is transmitted to the mechanical transmission assembly 4. When the clutch C.sub.6 49 and the one-way clutch F.sub.2 415 are engaged, the power in the mechanical transmission assembly 4 sequentially passes through the clutch C.sub.6 49, the one-way clutch F.sub.2 415, the front-set sun gear 41, and the front-set ring gear 43, and is then transmitted to the convergence mechanism sun gear 54. When the brake B.sub.6 51 is engaged, the convergence mechanism ring gear 52 is locked, and power passes through the convergence mechanism sun gear 54 and the convergence mechanism planet carrier 53 to the output shaft 6.

(102) In pure mechanical transmission, the rotation speeds of the input shaft 1 and the output shaft 6 are in the following relationship:

(103) in mechanical gear-1, n.sub.0=0.342n.sub.1;

(104) in mechanical gear-2, n.sub.0=0.637n.sub.1;

(105) in mechanical gear-3, n.sub.0=n.sub.1;

(106) in mechanical gear-4, n.sub.0=1.429n.sub.1;

(107) in mechanical reverse gear, n.sub.0=−0.420n.sub.1.

(108) Through model predictive control of the transmission system, the problem of globally optimal dynamic programming of fuel economy is transformed into the local optimization control problem in a prediction region, and the future vehicle operation status in the prediction region is continuously updated through rolling optimization, to obtain optimization results and realize real-time application of predictive control in the hydro-mechanical hybrid transmission system. Vehicle predictive control based on time domain is online rolling optimization control within the framework of model predictive control and implemented in combination with dynamic programming, and the principle thereof is shown in FIG. 18(a).

(109) In a prediction region q, the state transition equation of vehicle predictive control in hybrid transmission is:
x(k+1)=μ[x(k),u(k)]

(110) wherein μ is a time-discrete system function, x(k+1) is a state variable related to k+1, x(k) is a state variable related to k, and u(k) is a control variable related to k.

(111) In the prediction region q, an objective function of minimizing the fuel consumption of the hybrid transmission system is:

(112) $J_1=\min \underset{t=t\left(k\right)}{\overset{t=t\left(k+q\right)}{.Math.}}{v}_k\left(x_k,u_k\right)\mathrm{\Delta t}$

(113) wherein J.sub.1 is an objective function of fuel economy when a linear predictive control system is adopted, v.sub.k is a stage indicator of the k.sup.th stage, x.sub.k is a state variable of the k.sup.th stage, u.sub.k is a control variable of the k.sup.th stage, Δt is a time interval, t(k) is a time point of the k.sup.th stage, and t(k+q) is a time point of the (k+q).sup.th stage.

(114) In a control region p, a sensing device is generally adopted for measurement; and in the prediction region q, a GPS/GIS system is generally adopted for prediction. Prediction relies on the selection of an appropriate prediction window length for data collection as well as a high cost-performance ratio of the predictive control system.

(115) The structures of the predictive control systems are shown in FIG. 18(b). The vehicle dynamics model of the hybrid transmission system is of a typical nonlinear system, and needs to satisfy various constraints. The linear predictive control system can hardly describe the practical dynamics model of a vehicle system. Therefore, the nonlinear predictive control system is adopted to control dynamic characteristics and state variables of the hybrid transmission system, constrain control variables, estimate future states, and solve the online optimal control problem of a bounded region.

(116) In this case, the objective function of minimizing the fuel consumption of the hybrid transmission system is:

(117) $J_2=\min \underset{t=t\left(k\right)}{\overset{t=t\left(k+q\right)}{.Math.}}L\left[x\left(t\right),u\left(t\right)\right]$

(118) wherein J.sub.2 is an objective function of fuel economy when a nonlinear predictive control system is adopted, L is an instantaneous fuel consumption function at a time point t, x(t) is a state variable at a time point t, and u(t) is a control variable at a time point t.