SUSPENSION DEVICE AND METHOD

Abstract

Suspension unit, comprising a control unit, for a utility vehicle, wherein the utility vehicle has a body floor, to which a first and a second axle are connected, wherein the utility vehicle comprises at least one vehicle seat and/or a vehicle cab that can be suspended by a suspension device relative to the body floor, wherein the vehicle seat and/or the vehicle cab is arranged substantially above the second axle seen in a vertical direction, wherein, when driving over a bump with the first axle, a value of a deflection of the first axle by the disturbance can be determined by at least one sensor, and wherein the suspension device of the vehicle seat and/or vehicle cab can be varied by the control unit before or upon driving over the disturbance with the second axle.

Claims

1. A suspension unit, comprising a control unit, for a utility vehicle, wherein the utility vehicle has a body floor, to which a first and a second axle are connected, wherein the utility vehicle comprises at least one vehicle seat and/or a vehicle cab that can be suspended by a suspension device relative to the body floor, wherein the vehicle seat and/or the vehicle cab is arranged substantially above the second axle seen in a vertical direction, wherein when driving over a bump with the first axle, a value of a deflection of the first axle due to the disturbance can be determined by at least one sensor, wherein the suspension device of the vehicle seat and/or the vehicle cab can be varied by the control unit before or upon driving over the disturbance with the second axle.

2. The suspension unit according to claim 1, wherein the determined value of the deflection is comparable by the control unit with a presetable critical value, wherein when the critical value is exceeded, the suspension device can be varied by the control unit.

3. The suspension unit according to claim 1, wherein the suspension device can be varied by the control unit continuously as a function of the determined value of the deflection.

4. The suspension unit according to claim 1, wherein the at least one sensor is arranged on the first axle and is formed as an acceleration sensor and/or angle sensor for determining a resulting deflection and/or a resulting swinging movement of the front axle.

5. The suspension unit according to claim 1, wherein a speed of the utility vehicle and optionally the steering movement can be determined by the control unit.

6. The suspension unit according to claim 4, wherein a resulting vertical deflection and a resulting horizontal deflection of the vehicle seat and/or of the vehicle cab can be calculated by the control unit and the suspension device is adjustable depending on the vertical deflection and/or the horizontal deflection.

7. The suspension unit according to claim 1, wherein the suspension device comprises at least one damper element and at least one suspension element.

8. The suspension unit according to claim 1, wherein the suspension device comprises at least one actuator, which is operable electrically and/or pneumatically and/or hydraulically.

9. A method for suspending a vehicle seat and/or a vehicle cab by means of a suspension device relative to a body floor, characterised by the method steps: a. Driving over a bump with a first axle of a utility vehicle; b. Recording of sensor data by at least one sensor; c. Calculation of a deflection of the vehicle seat and/or vehicle cab using the sensor data by a control unit; d. Variation of the suspension device by the control unit before or upon driving over the disturbance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Other aims, advantages and functions of the present invention are to be inferred from the following from the description in connection with the drawing. In this,

[0040] FIG. 1A shows the utility vehicle when driving over a bump with a first axle;

[0041] FIG. 1B shows the utility vehicle when driving over a bump with a second axle;

[0042] FIG. 2 shows a recorded sensor signal;

[0043] FIG. 3 shows sensor signals for the first and the second axle;

[0044] FIG. 4 shows the construction of a utility vehicle according to an embodiment;

[0045] FIG. 5A shows a sensor arrangement according to an embodiment;

[0046] FIG. 5B shows a sensor arrangement according to another embodiment;

[0047] FIG. 6 shows a flow chart of a possible method;

[0048] FIG. 7 shows a flow chart of another possible method.

DETAILED DESCRIPTION

[0049] FIG. 1A shows a utility vehicle 1 with a body floor 2, on which a first axle 3 and a second axle 4 are arranged. Furthermore, a first wheel 11 is arranged on the first axle 3 and a second wheel 12 on the second axle 4. Naturally at least two wheels are arranged on each axle, wherein in this schematic side view only one wheel 11, 12 is recognisable on each axle 3, 4. The first axle 3 and the second axle 4 are arranged here running in a width direction B. The utility vehicle 1 is presently moving forwards at a constant speed v in a longitudinal direction L.

[0050] FIG. 1A also shows the situation in which the utility vehicle 1 is just driving over a bump 8 with the first axle 3, in particular the first wheel 11. The force acting or the deflection 13 of the first axle 3 are detected by a sensor 9 and transmitted to a control unit 14. This transfer can take place in a wired or wireless manner.

[0051] After driving over the bump 8, the utility vehicle 1 presently drives on at the constant speed v, so that after a certain time T the second axle, in particular the second wheel 12, drives over the bump 8. The time T can be calculated by means of the known equations of motion, wherein the time T is presently calculated by the control unit. The path covered between the first axle 3 and the second axle 4 corresponds to the known wheelbase.

[0052] Using the known equations of motion it is also possible to calculate the required time T by means of the control unit 14 if the speed v of the utility vehicle changes after driving over the bump with the first axle 3 and before driving over the bump 8 with the second axle 4.

[0053] The control unit 14 advantageously comprises a processor or a similar calculation unit for calculation purposes.

[0054] In FIG. 2, the values of the deflection recorded by the sensor 9 are shown. Moreover, a critical value of the deflection 10 according to a first preferred embodiment is shown, wherein below this value no active adjustment of any kind of the suspension device takes place, but only a passive adjustment. However, if the deflection exceeds the critical value 10, as indicated by the arrows, it is necessary to execute an active variation of the suspension device 7. Depending on the construction of the suspension device 7, thus in particular dependent on the choice of dampers, springs and/or actuators, another critical value can be specified. It is likewise conceivable to specify the critical value 10 depending on the understanding of ride comfort and the needs of the driver. This depends likewise on the nature of the terrain to be driven over and on the suspension travel of the suspension device 7 that is available.

[0055] FIG. 3 shows the progression of the deflections 13 as in FIG. 2, but for both the first axle 3 and the second axle 4, wherein the deflection of the second axle 4 is provided with the reference numeral 21. Since the vehicle is presently driving at a constant speed v over the ground, the deflection 13 is displaced in time compared with the deflection 21 only by a certain time T. If the utility vehicle 1 drives at a speed of 50 km/h and has a wheelbase of 3 m, then the utility vehicle 1 drives over the bump with the second axle 4 220 ms (rounded) later than the first axle 3.

[0056] If the speed were to change after driving over the bump, then the time would naturally also change accordingly. With a constant wheelbase of 3 m, the time required for a speed of 10 km/h is 1.1 s and for a speed of 30 km/h it is 370 ms.

[0057] Since the average processing time T1 of the signals of the sensor is roughly 20 ms, the control unit can make a change to the suspension device corresponding to the deflection, so that when driving over the bump with the second axle 4 the vehicle seat and/or the vehicle cab is already preconditioned to the deflection acting on it. In general, the processing time T1 is considerably smaller than the time T by which it can be indicated when the second axle 4 drives over the bump 8.

[0058] FIG. 4 shows the structural arrangement of the first axle 3, the control unit 14 and a vehicle seat 5, wherein a vehicle cab 6 (not shown here) or a combination of the two is naturally also possible. As is to be recognised, a track width 20 of the first axle 3 is equal to the track width 20 of the second axle 4, as is prevalent in the case of larger tractors or other agricultural utility vehicles in particular. In particular, it can be determined more easily by this whether the track of the second axle 4 follows the first axle 3.

[0059] In this case the assembly A1 comprises the first axle 3 as well as the required sensors, the assembly A2 the control unit and the assembly A3 the vehicle seat and the suspension device.

[0060] It is naturally possible that only one wheel 11 drives over the bump. It is therefore advantageous to use at least two sensors 9, which can each be connected to the first axle 3. The sensors 9 are advantageously arranged at the ends of the first axle 3 in its longitudinal extension. However, if it is a single-wheel suspension, then at least one sensor 9 is arranged on each of the single axles respectively.

[0061] FIGS. 5A and 5B show two different embodiments, wherein both embodiments have two sensors 9, which are each arranged close to an end 15, 16 of the first axle 3. The sensors 9 can be an acceleration sensor or an angle sensor. It is also conceivable that both acceleration sensors and angle sensors are used.

[0062] In the embodiment according to FIG. 5A, the signals 17, 18 of the two sensors 9 are each tapped separately and transmitted to the control unit 14 (not shown here).

[0063] In the embodiment according to FIG. 5B, the signals 17, 18 of the sensors 9 are averaged by the control unit 14. In this case, the values transmitted are preferably offset with a vehicle-specific amplification factor.

[0064] However, no information may be lost by an averaging of the signals 17, 18. If single-wheel suspensions are involved here, two sensors 9 are arranged at the axle ends. The resulting vertical deflection in the middle of the vehicle as well as the resulting swinging of the first axle 3 are calculated here, wherein a conclusion can then be drawn from this about the movement of the vehicle 1, in particular when driving over a disturbance 8 with the second axle 4.

[0065] If a rigid axle is involved, on the other hand, to which the wheels can be attached, then the deflection in the middle of the vehicle is determined and the swinging of the first axle 3 is determined, advantageously by a rotation sensor.

[0066] The signals 17, 18 and the averaged signal 19 are received by the control unit 14. It is understood that the respective components have devices for transmitting and receiving signals and suitable connections, for example lines or cables, are arranged between the components for transmitting signals.

[0067] The speed v of the utility vehicle can also be determined by the control unit. In addition, it is conceivable to detect and record the steering movement.

[0068] Determination of the steering movement is sensible to the extent that it can be determined using this and with the aid of the vehicle geometry whether the second wheel, which is preferably arranged behind the first wheel seen in a longitudinal direction, also drives over the bump that is driven over by the first wheel, or whether the second wheel drives past the bump.

[0069] Moreover, it also makes sense to determine the steering movement in order to determine the effects of the bump on the horizontal suspension of the vehicle seat and/or the vehicle cab. Due to the steering movement and with the driven speed of the vehicle 1 at least a centrifugal force is produced, which acts in particular on the horizontal suspension and causes a horizontal deflection. However, this centrifugal force has a smaller influence on the suspension device than the impulse due to the second axle 4 driving over a disturbance 8. Thought has therefore been given according to the invention to determining the lift and/or the swinging of the second axle before or upon driving over the bump 8.

[0070] It is thus possible by means of the control unit to calculate the resulting vertical deflection and the resulting horizontal deflection of the suspension device and accordingly of the vehicle seat and/or the vehicle cab.

[0071] Alternatively, a second control unit can be provided, which assumes the calculation of the vertical deflection and optionally of the horizontal deflection. The first control unit then determines only the speed and optionally, if required, the steering movement. The set-up of the sensors and the control unit, if the control unit is the only control unit, is then as follows. The sensors transmit the values, signals or the like recorded to the control unit and the control unit receives these. Furthermore, the control unit determines or calculates the speed v of the vehicle and optionally the steering movement. In this case the control unit also calculates the resulting vertical and horizontal deflection of the vehicle seat and/or the vehicle cab and activates the suspension device accordingly if an override was detected in a comparison of the deflection with the critical deflection. If no override was detected, the suspension device is not activated. The value of the deflection corresponds to the resulting vertical deflection and/or horizontal deflection. Activation of the suspension device 7 is the control of the suspension and/or damping or an active control of the suspension device 7.

[0072] The critical value is preferably chosen in such a way that it corresponds to the maximum suspension travel of the suspension device, thus in particular to the maximum suspension travel in a vertical direction and the maximum suspension travel in a horizontal direction, if a horizontal suspension is present.

[0073] The suspension device of the vehicle seat and/or the vehicle cab preferably comprises at least one damper, at least one suspension element and optionally an actuator, which is preferably connectable to the suspension element.

[0074] The at least one damper can be a standard damper, which is formed for example as a single- or twin-tube damper. The suspension element can be formed in this case as a fluid spring, wherein the fluid is preferably air. It is possible by means of the actuator to influence the suspension properties of the suspension element. The height of the vehicle seat and/or the vehicle cab can preferably also be varied by a variation in the fluid spring by the actuator. Alternatively or cumulatively, the suspension device 7 can be actively adjusted by the actuator. The actuator can be formed electrically, pneumatically or hydraulically in this case.

[0075] In FIG. 6, a preferred method sequence is represented by a flow chart. Other or further method steps are naturally also conceivable here. The present embodiment here comprises a single control unit, wherein further control units are naturally also conceivable.

[0076] In a first step, the first axle 3 of the utility vehicle 1 drives over a bump 8, wherein in a following step the effects, in particular the acceleration and the amplitude of the impulse, can be recorded by at least one sensor 9. In a further step, the data recorded by the sensor 9 are transmitted to the control unit 14, wherein the control unit 14 determines the speed v of the utility vehicle 1 and if applicable a steering movement.

[0077] In particular, the values of the speed and the steering angle are transmitted and with the complete knowledge of the disturbance, the corresponding adjustment is started simultaneously with the start of the excitation of the second axle or with the start of the resulting seat and/or cab reaction, or the seat and/or the cab is/are actively preconditioned or preadjusted even before the beginning of the excitation.

[0078] A resulting vertical deflection and a resulting horizontal deflection of the vehicle seat and/or of the vehicle cab are calculated from these values and compared with a presetable critical value of the deflection. If the critical value is not exceeded, then the existing suspension travel of the suspension device is sufficient to carry out suspension or damping. In this case preferably purely passive suspension or damping is involved.

[0079] On the other hand, if the calculated value exceeds the critical value, a corresponding active adjustment of the suspension device is carried out. For example, the characteristic curve of the suspension element can be varied and/or the suspension device 7 can be actively adjusted by an actuator. By suitably varying the properties of the suspension device in such a way that the existing suspension travel is now adequate, maximum rebound of the vehicle seat and/or the vehicle cab is prevented. The variation in the properties of the suspension device is preferably made when the utility vehicle 1 drives over the bump 8 with the second axle 4, so that an optimally adjusted suspension device is present already at the time of driving over the bump 8 with the second axle.

[0080] In FIG. 7, another preferred method sequence is represented by a flow chart. Other or further method steps are naturally conceivable here too. The present embodiment in this case comprises a single control unit, wherein further control units are naturally also conceivable.

[0081] In a first step, the first axle 3 of the utility vehicle 1 drives over a bump 8, wherein in a following step, the effects, in particular the acceleration and the amplitude of the impulse, are recorded by at least one sensor 9. In a further step, the data recorded by the sensor 9 are transmitted to the control unit 14, wherein the control unit 14 determines the speed v of the utility vehicle 1 and if applicable a steering movement 1.

[0082] From these values a resulting vertical deflection and a resulting horizontal deflection of the vehicle seat and/or the vehicle cab are calculated. Due to this calculation, the suspension device 7 of the second axle 4 can now be adapted continuously to the disturbance information of the first axle 3 by the control unit 14, so that the suspension device 7 is already adjusted before or upon driving over the bump 8, wherein active adjustment in particular can take place. The adjustment of the suspension device 7 can be carried out in this case relative to the value determined, for example by means of a conversion formula or the like.

[0083] All the features disclosed in the application documents are claimed as substantial to the invention inasmuch as they are new individually or in combination compared with the prior art.

LIST OF REFERENCE NUMERALS

[0084] 1 Utility vehicle [0085] 2 Body floor [0086] 3 First axle [0087] 4 Second axle [0088] 5 Vehicle seat [0089] 6 Vehicle cab [0090] 7 Suspension device [0091] 8 Bump [0092] 9 Sensor [0093] 10 Critical value [0094] 11 First wheel [0095] 12 Second wheel [0096] 13 Deflection [0097] 14 Control unit [0098] 15 First end of the first axle [0099] 16 Second end of the first axle [0100] 17 Signal [0101] 18 Signal [0102] 19 Averaged signal [0103] 20 Track width [0104] 21 Deflection [0105] L Longitudinal direction [0106] H Vertical direction [0107] B Width direction