Apparatus for controlling/regulating the travel speed of a utility vehicle and method for same

Abstract

The present disclosure relates to an apparatus for controlling/regulating the travel speed of a utility vehicle comprising at least one drive motor, at least one hydraulic pump, at least one control slide valve, at least one hydraulic travel motor, at least one further hydraulic drive, as well as at least one controller. In accordance with the present disclosure, the travel speed of the at least one hydraulic travel motor is controlled/regulated via at least the speed of the drive motor, while the at least one further hydraulic drive does not provide any drive power.

Claims

1. An apparatus for controlling/regulating a travel speed of a utility vehicle comprising at least one drive motor, at least one hydraulic pump, exactly one control slide valve, at least one hydraulic travel motor, at least one further hydraulic drive as well as at least one controller, wherein during a purely vehicle traveling operation, the travel speed of the at least one hydraulic travel motor is controlled/regulated via a speed of the drive motor and a supply pressure of a pressure medium supplied to the at least one hydraulic travel motor by the at least one hydraulic pump is not restricted by the control slide valve, while the at least one further hydraulic drive does not produce any drive power, and wherein the supply pressure of the pressure medium supplied to the at least one hydraulic travel motor by the at least one hydraulic pump is restricted by the control slide valve only during operation of one or more further consumers of the utility vehicle.

2. The apparatus in accordance with claim 1, wherein the hydraulic pump is fully outwardly pivoted.

3. The apparatus in accordance with claim 1, wherein a direction of rotation of the at least one hydraulic travel motor is controlled/regulated via the control slide valve.

4. The apparatus in accordance with claim 1, wherein the travel speed of the at least one hydraulic travel motor is controlled/regulated via a setting of a pivot angle of the hydraulic travel motor.

5. The apparatus in accordance with claim 1, wherein the travel speed of the at least one hydraulic travel motor is controlled/regulated via a setting of a pivot angle of the hydraulic pump.

6. The apparatus in accordance with claim 1, wherein the drive motor is a diesel engine.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows an apparatus for controlling/regulating the speed by the control slide valve in accordance with the prior art.

(2) FIG. 2 shows an apparatus for controlling/regulating the speed by the drive motor.

(3) FIG. 3 shows an apparatus for controlling/regulating the speed by the drive motor and the hydraulic travel motor.

(4) FIG. 4 shows an apparatus for controlling/regulating the speed by the drive motor, the hydraulic pump and the hydraulic travel motor.

(5) FIGS. 5a and 5b show a pressure volume flow diagram.

DETAILED DESCRIPTION

(6) FIG. 1 shows an apparatus 10 for controlling/regulating the speed of a utility vehicle. The utility vehicle itself is not shown in this respect, but rather illustrated schematically as 21. A drive motor 1 in this respect drives a hydraulic pump 2 to pressurize a pressure medium such as hydraulic oil. The pressure medium can be supplied to the control slide valve 4 via one of the hydraulic lines 3. It is the job of the control slide valve 4 to supply pressure medium in dependence on demand to one or more consumers.

(7) The example shown in this respect comprises an electrohydraulic precontrol 6 by which the control slide valve 4 can be precontrolled with respect to speed and direction of the hydraulic travel motor 5 via a pressure regulation valve 11 or a 4/3 way valve. The pressure regulation valve 11 can in this respect, for example, be configured as a hydraulic gas pedal 11. The travel motor may be coupled to a wheel, or track, that drives the vehicle.

(8) The control slide valve 4 inter alia reduces the supply pressure provided by the hydraulic pump 2 by a restrictor apparatus, for example, in order thus to reduce it to a lower load pressure required by one of the consumers. The power loss which occurs in this respect is discharged from the system as heat and cannot be used for the drive.

(9) FIG. 2 shows an apparatus 10 in accordance with the present disclosure which, unlike the prior art shown in FIG. 1, comprises a controller 7 which is connected on the input side to an input element 8 and on the output side to the drive motor 1. The controller 7 receives information on a desired travel speed of the utility vehicle via the input element 8 which can, for example, be the gas pedal of the utility vehicle or any other switch or regulator. If the controller 7 determines that no further consumers (e.g., further consumer 12) are operated except for the hydraulic travel motor 5, the controller 7 thus generates a signal corresponding to the received information and forwards it via a connection 9 to the drive motor 1 to set the rotational speed of the travel motor 1 in accordance with the desired travel speed. A restriction procedure thus no longer takes place in the region of the control slide valve 4 for the purpose of the travel speed control/regulation and the power losses occurring in the example of FIG. 1 are minimized.

(10) FIG. 3 shows an embodiment with a further intervention possibility for the control/regulation of the travel speed of the hydraulic travel motor 5. The controller 7 is not only connected to the drive motor 1 in this embodiment, but also via a second connection 9 to the hydraulic travel motor 5. It is possible at the hydraulic travel motor 5 itself to vary the pivot angle of the hydraulic travel motor 5 in dependence on the desired travel speed of the utility vehicle. Two intervention possibilities thus result in this embodiment for controlling/regulating the travel speed of the utility vehicle.

(11) An embodiment having three intervention possibilities for controlling/regulating the travel speed of the hydraulic travel motor 5 is shown in FIG. 4. The controller 7 is, as in the previous example, connected to the drive motor 1 and to the hydraulic travel motor 5 and can furthermore control/regulate the hydraulic pump 2 via a third connection 9. As the pivot angle of the hydraulic motor 5 in the previous embodiment can be varied by the controller 7, in the present third embodiment the pivot angle of the hydraulic pump 2 can thus be varied by the controller 7.

(12) Controller 7 may include a processor and memory, the memory including non-transitory instructions stored therein for adjusting the various actuators in response to sensed information, as described herein. For example, the travel speed of the hydraulic travel motor may be controlled/regulated by the controller via adjustment of the speed of the drive motor, while a further hydraulic drive does not produce any drive power, for example to propel the vehicle, the further drive motor controlled by the controller. Not producing any drive power may include not producing or supplementing any tractive effort of the vehicle, and my further include not producing any braking power as well.

(13) FIGS. 5a and 5b show the parameters of supply pressure (Pressure), load pressure (pLoad), volume flow and the pressure difference p between the supply pressure and the load pressure in dependence on one another. The volume flow and the supply pressure are in this respect normalized with respect to their respective maximum values.

(14) FIG. 5a shows the power loss graphically which results on the restriction procedure known from the prior art. The power loss is proportional to p which is dependent on the pressure difference between the supply pressure and the load pressure of the hydraulic travel motor 5 lower in comparison therewith.

(15) FIG. 5b in contrast shows the power loss of the apparatus 10 in accordance with the present disclosure or of the method in accordance with the present disclosure. It can be recognized in this respect that p is reduced by the possible direct control/regulation in accordance with the present disclosure of the drive motor 1, the pivot angle of the hydraulic travel motor 5 and/or the pivot angle of the hydraulic pump 2 with respect to the prior art. The same load pressure as in FIG. 5a can therefore be provided while applying a smaller supply pressure.

(16) The figures herein utilize standardized hydraulic symbols in the figures to represent particular hydraulic components as would be understood by one skilled in the art. For example, the hydraulic circuits illustrated in the figures include various pumps, sump returns, sump draws, etc., as indicated.