TOWING HITCH

Abstract

The disclosure relates to a towing hitch for a work vehicle. The towing hitch includes a retaining element. A coupling member coupled to the retaining element. A guide element having at least one guide channel formed therein; wherein the guide channel is sized to receive a portion of the retaining element. An actuator coupled to at least one surface of the retaining element, wherein the actuator is arranged such that lateral displacement of the actuator moves the retaining element between a first position and a second position within the guide channel of the guide element.

Claims

1. A towing hitch for use with a work vehicle, the towing hitch including: a retaining element; a coupling member coupled to the retaining element; a guide element having at least one guide channel formed therein; wherein the guide channel is sized to receive a portion of the retaining element; and an actuator coupled to at least one surface of the retaining element, wherein the actuator is arranged such that lateral displacement of the actuator moves the retaining element between a first position and a second position within the guide channel.

2. The towing hitch of claim 1, wherein the coupling member is continuously displaceable.

3. The towing hitch of claim 1, wherein the actuator includes at least one of a pneumatic cylinder or a hydraulic cylinder.

4. The towing hitch of claim 1, further including at least one sensor and a processing unit for adjusting a position of the coupling member.

5. The towing hitch of claim 1, wherein the retaining element includes a rectangular plate.

6. The towing hitch of claim 1, wherein the guide element is integrally coupled to an attachment block.

7. The towing hitch of claim 1, wherein the guide channel includes a grooved guide channel.

8. The towing hitch of claim 1, wherein the coupling member is arranged displaceably in and contrary to the driving direction.

9. The towing hitch of claim 8, wherein the coupling member is a ball-head coupling.

10. A method for adjusting a position of a coupling member of a towing hitch of a work vehicle, the method including: positioning the coupling member within a retaining element; detecting, via a sensor, data associated with a work vehicle; determining a position of the coupling member via a processing unit based on the data; and adjusting a position of the coupling member within the retaining element from a first position to the position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The detailed description of the drawings refers to the accompanying figures in which:

[0021] FIG. 1 is a schematic illustration of a work vehicle having a towing hitch and a hydraulic actuator attached thereto according to an embodiment;

[0022] FIG. 2 is a schematic diagram of a hydraulic actuator according to an embodiment;

[0023] FIG. 3 is a perspective view of a supporting structure of an work vehicle having a towing hitch attached thereto according to an embodiment;

[0024] FIG. 4 is an expanded and enlarged representation of the supporting structure of FIG. 3 according to an embodiment;

[0025] FIG. 5 is a bottom perspective view of a towing hitch according to an embodiment;

[0026] FIG. 6 is a perspective view of a towing hitch according to an embodiment;

[0027] FIG. 7 is a side view of a towing hitch according to an embodiment;

[0028] FIG. 8 is a schematic illustration of a work vehicle for calculating the turning radius;

[0029] FIG. 9 is a schematic illustration of a vehicle combination for calculating the turning radius according to an embodiment;

[0030] FIG. 10 is a schematic illustration of a working visibility range while hitching; and

[0031] FIG. 11 is a schematic illustration for calculating an axle load displacement.

DETAILED DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 shows a work vehicle 1 that is provided with a towing hitch 2, which is arranged displaceable longitudinally in the horizontal direction by means of an actuator 3, in or contrary to the travel direction. FIG. 1 shows the towing hitch 2 both in a first position X.sub.1 close to the work vehicle 1, and in a second position X.sub.2 at a corresponding distance from the work vehicle 1. As previously discussed, the term longitudinally displaceable may mean a displacement in or contrary to the direction of travel. The coupling member 14 may be displaced largely horizontally. The term largely horizontally may mean an angle to the horizontal of less than 45, less than 30, or in some embodiments less than 15.

[0033] The actuator 3 is driven by an arrangement 4. The supply pressure for the arrangement 4 for driving the actuator 3 is labeled p.sub.v. The longitudinal displacement is represented in the figures with the symbol l.sub.DB. Two positions (e.g., X.sub.1, X.sub.2) of the towing hitch 2 are shown in

[0034] FIG. 1. As illustrated in FIG. 1, the first position X.sub.1 has a shorter longitudinal displacement l.sub.DB1 than that of the second position X.sub.2, which has a larger longitudinal displacement l.sub.DB2.

[0035] FIG. 2 shows a schematic illustration of an actuator 3 and an arrangement 4 for controlling or regulating the actuator 3. The actuator 3 is a hydraulic cylinder 31 in which a piston 29 is displaceably arranged, but may vary in other embodiments. For example, in other embodiments, the hydraulic cylinder 31 may include a pneumatic cylinder or other suitable working cylinders specific to design and/or application requirements. In FIG. 2, the reference character p.sub.LS designates the load sensing pressure. The piston 29 separates two chambers 5, 6 in the hydraulic cylinder 31. A first line 7 leads to the chamber 5 and a second line 8 leads to the chamber 6.

[0036] In comparison to the use of conventional wheel weights, the present disclosure offers the advantage of a continuous shifting of the axle load. This continuous shifting proves particularly favorable relative to the use of wheel weights because wheel weights are only available in fixed weight gradations, for example, 50 kg, 100 kg or 250 kg. In the wheel load distribution, a tensile force F.sub.DB may additionally lead to displacement of the axle load from the front to the rear axle 12. The towing hitch 2 according to the present disclosure and the method according to the present disclosure make it possible to compensate for this effect within certain limits. To implement this, the effect of the axle load shift must be quantitatively determined via the tensile force F.sub.DB. In the presentation in FIG. 2, the towing hitch 2 may be provided with two pressure sensors (i.e., a first pressure sensor 9 and a second pressure sensor 10). The first pressure sensor 9 detects the pressure in the line 7 or the chamber 5. This pressure is designated p.sub.2. The second pressure sensor 10 detects the pressure in the line 8 or the chamber 6. The pressure is designated p.sub.1.

[0037] The tensile force F.sub.DB may be determined with the aid of the first and second pressure sensors 9, 10. For example, by determining the pressure p.sub.2 in the rod chamber 5 of the hydraulic cylinder 31 and the pressure p.sub.1 in the rod-free chamber 6 of the hydraulic cylinder 31, the tensile force F.sub.DB may be determined by way of the corresponding respective surface areas A.sub.2 and A.sub.1 according to the following formula:

F.sub.DB=A.sub.2.Math.p.sub.2A.sub.1.Math.p.sub.1(Eq. 1)

For example, the towed load may be determined by determining the tensile force F.sub.DB, which is important for the driving strategy of the work vehicle 1.

[0038] A determination of the tensile force F.sub.DB additionally allows an implementation of a braking strategy for the vehicle combination. For braking of the tractor/towed vehicle combination, a force-free tractor/trailer connection is desired, in which the tensile force F.sub.DB is equal to zero in an ideal case. By determining the tensile force F.sub.DB, this objective may be achieved with a suitable braking strategy.

[0039] In other embodiments, the towing hitch 2 may include one or more sensors (not shown) that may collect data and then transfer it to a corresponding processing unit, which then determines a position of the coupling member 14 on the basis of the data. In turn, the actuator 3 is driven accordingly so that it brings the coupling member 14 into a position for a given situation by means of a lateral displacement. The processing unit may be an evaluation device, a control device, a regulation device, or other suitable processing device. For example, an electronic data controller such as a PID controller or a programmable logic controller (PLC) may be used for this purpose. The position of the coupling member 14 is determined on the basis of the collected data. A driving behavior of the work vehicle 1 may be achieved.

[0040] FIG. 3 shows a supporting structure 11 of the work vehicle 1, which structure is constructed in the present embodiment as a rear axle casing 27, and further shows the rear axle 12 of a tractor. An attachment block 13, in which a towing hitch 2 is integrated, is also shown.

[0041] FIG. 4 shows an enlarged representation of the region in FIG. 3. In the embodiment according to FIG. 4, the coupling member 14 is constructed as a ball-head coupling. The coupling member 14 is arranged on a retaining element 15, which is designed in the embodiment as a plate. The retaining element 15 is displaceably arranged in a guide element 16. In the embodiment, the guide element 16 is a formation of the attachment block 13 that has a groove 21 for guiding the retaining element 15.

[0042] The groove 21 of the retaining element 16 may include a generally U-shaped configuration and may be arranged to surround the plate-like retaining element 15 at the laterally outward projecting end faces 17 thereof. According to the present disclosure, the retaining element 15 is arranged displaceably in the longitudinal direction, so that it may be extended to the rear with the actuator 3 shown in FIG. 4.

[0043] FIG. 5 shows a bottom perspective view of the attachment block 13 from below. The attachment block 13 includes two side cheeks 18 which are arranged vertically and parallel to one another. The attachment block 13 is connected by at least one fastening means 19 to a rear-end part of the work vehicle 1. The rear-end part may include a power takeoff casing or a differential casing of the work vehicle 1 such as a tractor.

[0044] A power takeoff 20 is visible in FIGS. 3 and 6. The embodiment according to FIG. 5 shows the actuator 3, which moves the retaining element 15 together with the coupling member 14 within the groove 21 (e.g., a guide groove) axially to the rear.

[0045] FIG. 6 shows, in a bottom perspective view, a supporting structure 11 of the work vehicle 1, which is formed by a rear axle casing 27 of the work vehicle 1 (e.g., a tractor), as well as the laterally outward-protruding tractor rear axle 12. The attachment block 13 is connected to the supporting structure 11. The attachment block 13 includes the displaceably arranged towing hitch 2.

[0046] FIG. 7 shows, in a side view, the rear axle casing 27 of the work vehicle 1 (e.g., a tractor) with an attachment block 13 that includes the towing hitch 2. The actuator 3 is connected via a fastening element 22 to the supporting structure 11. For example, as shown in FIG. 7, the actuator 3 may be mounted to a bottom on the rear axle casing 27. At the end of an extendable rod, the actuator 3 has a fastening element 23, with which the extendable hydraulic rod of the actuator 3 is connected to the retaining element 15 of the towing hitch 2. The retaining element 15 is designed according to the embodiment in FIG. 7 as a rectangular plate extending longitudinally in the driving direction. The longitudinal extent enables an extension of the plate to the rear so that the coupling member 14 may be brought into the desired position. The retaining element 15, designed as an elongated plate, is displaced within the groove 21 of the guide elements 16.

[0047] FIGS. 8 and 9 show a reduction of the turning radius of a combination of an implement and the work vehicle 1. The maximum turning angle .sub.E is limited via the lower link of a lifting mechanism. The geometric proportions assumed below are used for illustrating the orders of magnitude and are oriented to typical tractors on the market. With a typical configuration on the market (l.sub.DB=0.7 m), the following maximum possible turning angle results:

[00001]$\begin{array}{cc}{}_E=\arctan \left(\frac{l_{U.Math..Math.1}}{l_{U.Math..Math.2}-l_{\mathrm{DB}}}\right)33.Math.& \left(\mathrm{Eq}..Math.2\right)\end{array}$

which yields the following turning radius of the center point of the rear axle 12 of the tractor:

[00002]$\begin{array}{cc}=\frac{l_W+\cos \left({}_E\right).Math.l_{\mathrm{DB}}}{\sin \left({}_E\right)}13.Math..Math.m& \left(\mathrm{Eq}..Math.3\right)\end{array}$

with the steering angle

[00003]$\begin{array}{cc}{}_L=\arctan \left(\frac{l}{r}\right)12.6.Math.& \left(\mathrm{Eq}..Math.4\right)\end{array}$

[0048] With an increase of l.sub.DB by =0.3 m to l.sub.DB=1 m, a significant reduction of the turning radius r may already be achieved:

l.sub.DB1.00m.fwdarw..sub.E53.fwdarw.r8.9m.fwdarw..sub.L18(Eq.5).

[0049] In FIG. 10, an illustration of the work vehicle 1 having the supporting structure 11 and the towing hitch 2 mounted thereto is shown. For example, FIG. 10 provides an illustration of how the towing hitch 2 according to the present disclosure may guarantee visibility when coupling and decoupling the implement to the work vehicle 1. As shown in FIG. 10, the coupling member 14, designed as a ball-head coupling, may be inserted horizontally in the towing hitch 2 at a lower end of a coupling rail 24. Therefore, it is not visible to the driver from the cab. If a drawbar coupling 25 is installed, it considerably restricts the view of the ball-head coupling. The restriction of the field of view increases with increasing height of the coupling arrangement. If the drawbar coupling 25 is fixed in the highest perforation of the coupling rail 24, the coupling member 14 must be pushed longitudinally by 0.6 m up to the height of the lower links so that it is visible from the cab. This extension preferably takes place without a full support load. If no drawbar coupling 25 is installed, the view is restricted by the coupling rail 24. In this case, an extension of 0.3 m is sufficient to establish visual contact from the cab.

[0050] FIG. 11 shows the mode of operation of the towing hitch 2 of the present disclosure for axle load shifting. In order to be able to represent the influence and the mode of operation of a continuously longitudinally displaceable ball-head coupling, the crucial relationships are initially derived by using a rigid one-body model of a tractor in the plane

m{umlaut over (x)}=F.sub.Z.sup.R+F.sub.Z.sup.FF.sub.DBF.sub.W(Eq. 6)

m=F.sub.R.sup.R+F.sub.R.sup.FGF.sub.S(Eq. 7)

J{umlaut over ()}=F.sub.Z.sup.Fh+F.sub.Z.sup.RhF.sub.DBh.sub.DB+F.sub.S(l.sub.DB+l.sub.R)+l.sub.FF.sub.R.sup.Fl.sub.RF.sub.R.sup.R(Eq. 8)

The vertical and yawing dynamics are negligible compared to the longitudinal dynamics

{dot over (x)}>>{dot over (y)}{dot over (x)}>>{dot over ()}.fwdarw.!=0{umlaut over ()}!=0(Eq. 9)

The influence of the weight force as a function of the angle of inclination is as follows:

G=mg cos ()(Eq. 10)

F.sub.W=mg sin ()(Eq. 11).

The axle loads result as

[00004]$\begin{array}{cc}{F}_R^R=\frac{h}{l}.Math.m.Math.\stackrel{\mathrm{.Math.}}{x}+\left(\frac{h}{l}.Math.\sin \left(\right)+\frac{l_F}{l}.Math.\cos \left(\right)\right).Math.\mathrm{mg}+\frac{h-h_{\mathrm{DB}}}{l}.Math.F_{\mathrm{DB}}+\left(1+\frac{l_{\mathrm{DB}}}{l}\right).Math.F_S& \left(\mathrm{Eq}..Math.12\right)\\ F_R^F=\underset{\underset{\mathrm{Acceleration}}{}}{-\frac{h}{l}.Math.m.Math.\stackrel{\mathrm{.Math.}}{x}}-\underset{\underset{\begin{array}{c}\mathrm{Increased}.Math..Math.\mathrm{weight}\\ \mathrm{force}\end{array}}{}}{\left(\frac{h}{l}.Math.\sin \left(\right)-\frac{l_R}{l}.Math.\cos \left(\right)\right).Math.\mathrm{mg}}-\underset{\underset{\mathrm{Tensile}.Math..Math.\mathrm{force}}{}}{\frac{h-h_{\mathrm{DB}}}{l}.Math.F_{\mathrm{DB}}}-\underset{\underset{\begin{array}{c}\mathrm{Support}\\ \mathrm{load}\end{array}}{}}{\frac{l_{\mathrm{DB}}}{l}.Math.F_S}& \left(\mathrm{Eq}..Math.13\right)\end{array}$

The different influences on the axle loads and the displacement thereof are thus known. Depending on the support load F.sub.S the axle load may be shifted according to the present disclosure by varying l.sub.DB. Wheel weights are typically mounted on the rear axle 12 up to a total weight of m.sub.RG=600 kg. With a support load effect of m.sub.S=4000 kg, a longitudinal displacement of

[00005]$\begin{array}{cc}=\frac{m_{\mathrm{RG}}}{m_S}.Math.l0.4.Math..Math.m& \left(\mathrm{Eq}..Math.14\right)\end{array}$

is necessary in order to achieve the identical wheel load increase on the rear axle 12 by using the present disclosure. It should be noted that the increase in wheel load at the rear axle 12 by means of the disclosure leads to a corresponding relief of the front axle. As such, to provide the necessary balance, in other embodiments, the work vehicle 1 may include a front ballast (not shown). In some embodiments, the front ballast may be movably arranged and longitudinally displaced. Such an arrangement is particularly advantageous in that it provides for stability of the work vehicle 1 in various applications and modes of operations. For example, it allows for the position of the towing hitch 2 and/or the front ballast relative to the work vehicle 1 to be shifted during driving operation, which, in turn, may optimize the driving stability.

[0051] Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein is an improved towing hitch that enables a small turning radius of the work vehicle combination. The towing hitch of the present disclosure is also intended to contribute to a load optimization of the work vehicle (e.g., an agricultural or construction vehicle). In turn, the vehicle combination should have better driving and braking properties as a result of the towing hitch according to the present disclosure. In addition, stable driving behavior should be achieved.

[0052] While the above describes example embodiments of the present disclosure, these descriptions should not be viewed in a limiting sense. Rather, other variations and modifications may be made without departing from the scope and spirit of the present disclosure as defined in the appended claims.