LOAD-CONTROLLED HYDRAULIC SUPPLY FOR A UTILITY VEHICLE

Abstract

A load-controlled hydraulic supply for a utility vehicle includes a variable-displacement pump supplied with hydraulic fluid from a hydraulic reservoir. The variable-displacement pump has a mechanically actuable control slide for changing a volume flow delivered. An electrical actuator is configured to actuate the control slide. A controller is configured to control the electrical actuator in accordance with a determined load requirement on a consumer side.

Claims

1. A load-controlled hydraulic supply for a utility vehicle, comprising: a variable-displacement pump supplied with hydraulic fluid from a hydraulic reservoir, the variable-displacement pump having a mechanically actuable control slide for changing a volume flow delivered; an electrical actuator configured to actuate the control slide; and a controller configured to control the electrical actuator in accordance with a determined load requirement on a consumer side.

2. The hydraulic supply of claim 1, wherein the load requirement on the consumer side is determined via a pressure sensor, which is used to detect a load signaling pressure of a hydraulic consumer, which is applied to a feedback line.

3. The hydraulic supply of claim 1, wherein the controller controls the electrical actuator in respect of a modification of a functional relationship existing between the volume flow delivered and the drive-side pump speed.

4. The hydraulic supply of claim 3, wherein the modification on the part of the controller is carried out in such a way that the volume flow delivered by the variable-displacement pump assumes a constant value when a predetermined maximum value of the pump speed is reached.

5. The hydraulic supply of claim 3, wherein the modification on the part of the controller is performed such that the volume flow delivered by the variable-displacement pump is adapted to maintain a predetermined power characteristic of a drive motor provided for the operation of the variable-displacement pump.

6. A utility vehicle including a load-controlled hydraulic supply, comprising: a variable-displacement pump supplied with hydraulic fluid from a hydraulic reservoir, the variable-displacement pump having a mechanically actuable control slide for changing a volume flow delivered; an electrical actuator configured to actuate the control slide; and a controller configured to control the electrical actuator in accordance with a determined load requirement on a consumer side.

7. The utility vehicle of claim 6, wherein the load requirement on the consumer side is determined via a pressure sensor, which is used to detect a load signaling pressure of a hydraulic consumer, which is applied to a feedback line.

8. The utility vehicle of claim 6, wherein the controller controls the electrical actuator in respect of a modification of a functional relationship existing between the volume flow delivered and the drive-side pump speed.

9. The utility vehicle of claim 8, wherein the modification on the part of the controller is carried out in such a way that the volume flow delivered by the variable-displacement pump assumes a constant value when a predetermined maximum value of the pump speed is reached.

10. The utility vehicle of claim 8, wherein the modification on the part of the controller is performed such that the volume flow delivered by the variable-displacement pump is adapted to maintain a predetermined power characteristic of a drive motor provided for the operation of the variable-displacement pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The load-controlled hydraulic supply according to the disclosure for a utility vehicle will be described in more detail below with reference to the drawings. In the drawings:

[0020] FIG. 1 shows a schematically illustrated exemplary embodiment of the load-controlled hydraulic supply according to the disclosure; and

[0021] FIG. 2 shows an illustrative profile of a functional relationship existing between the volume flow delivered and the drive-side pump speed.

DETAILED DESCRIPTION

[0022] The embodiments or implementations disclosed in the above drawings and the following detailed description are not intended to be exhaustive or to limit the present disclosure to these embodiments or implementations.

[0023] FIG. 1 shows a schematically illustrated exemplary embodiment of the load-controlled hydraulic supply according to the disclosure for a utility vehicle.

[0024] In the present case, the utility vehicle (not shown) is an agricultural tractor 10, which is equipped with a load-controlled hydraulic supply 12 designed as a load-sensing system. The load-controlled hydraulic supply 12 comprises a variable-displacement pump 16 fed with hydraulic fluid from a hydraulic reservoir 14, which has a control slide 20 that can be actuated by means of an electrical actuator or electrical actuating means 18, wherein a control unit 22 (e.g., a controller including a processor and memory) controls the electrical actuating means 18 in accordance with a determined load requirement on the consumer side.

[0025] The electrical actuating means 18 is an electromagnetic actuator 24, which is connected for control to a power output 26 of the control unit 22, thus enabling the control slide 20 to be deflected against a restoring spring force with a corresponding increase in the volume flow Q.sub.pump delivered by the variable-displacement pump 16. The extent of the deflection is detected by means of a travel sensor 28 and fed back to the control unit 22 in order to implement a control loop.

[0026] For the sake of clarity, other typical components of the hydraulic supply 12, such as valve assemblies for controlling hydraulic consumers, are not shown and play no role in understanding the function of the hydraulic supply 12. Moreover, FIG. 1 shows just a single representative hydraulic consumer 32, which is operated via an associated supply line 30 and is a hydraulically operated vehicle equipment item or the like. Here, after the hydraulic power conversion, the hydraulic fluid leaves the hydraulic consumer 32 in the direction of the hydraulic reservoir 14 via a return line 34. In addition, further hydraulic consumers may be present, including those which can be connected externally via a hydraulic interface of the agricultural tractor 10 in order to carry out agricultural work functions.

[0027] According to the example, the variable-displacement pump 16 is usually set in rotation by a drive motor 38 designed as a diesel engine 36, which is simultaneously a component of a travel drive of the agricultural tractor 10, via a belt drive 40 and/or an intermediate transmission 42, thus ensuring that the engine speed n.sub.eng and pump speed n.sub.pump are related to one another in accordance with a fixed transmission ratio.

[0028] The load requirement on the consumer side is determined by means of a pressure sensor 44, which is used to detect a load signaling pressure p.sub.feedbk of the hydraulic consumer 32, which is applied to a feedback line 46. In this case, the sensor signal generated by the pressure sensor 44 is converted in such a way by the control unit 22 into a control signal provided for actuating the electrical actuating means 18 that the higher the load signaling pressure p.sub.feedbk applied to the feedback line 46, the higher the volume flow Q.sub.pump delivered by the variable-displacement pump 16.

[0029] A further pressure sensor 48, which communicates with the supply line 30, is used to detect the operating pressure p.sub.pump generated by the variable-displacement pump 16, wherein the control unit 22 throttles the delivery volume flow Q.sub.pump generated by the variable-displacement pump 16 by appropriate actuation of the electrical actuating means 18 if, by evaluation of the sensor signals provided by the further pressure sensor 48, the said control unit detects that the operating pressure p.sub.pump exceeds a permissible maximum value.

[0030] FIG. 2 shows a typical profile of a functional relationship 50 existing between the volume flow Q.sub.pump delivered and the drive-side pump speed n.sub.pump. For comparison purposes, the dot-dash line 52 shows the profile reduced to the dependence of the volume flow Q.sub.pump delivered on the pump speed n.sub.pump. This corresponds to the control behavior of a conventional variable-displacement pump, in which direct (purely) mechanical actuation of the control slide is accomplished by means of the load signaling pressure.

[0031] As a departure therefrom, it is now envisaged that the control unit 22 controls the electrical actuating means 18 in respect of a targeted modification of the functional relationship 50 existing between the volume flow Q.sub.pump delivered and the drive-side pump speed n.sub.pump. The modification can take account of different operating situations.

[0032] Thus, in a first section A, the modification on the part of the control unit 22 is carried out in such a way that the volume flow Q.sub.pump delivered by the variable-displacement pump 16 assumes a constant value Q.sub.max when a predetermined maximum value n.sub.max of the .sub.pump speed n.sub.pump is reached. In this case, the volume flow Q.sub.pump delivered remains at least substantially unchanged, even if the pump speed n.sub.pump continues to increase beyond the predetermined maximum value n.sub.max. This ultimately represents a limitation on the drive power to be produced by the diesel engine 36 by capping of the delivery capacity of the variable-displacement pump 16, thereby making it possible to prevent the diesel engine 36 from being operated in a comparatively inefficient power characteristic range. Similar considerations apply to the dimensioning of the intermediate transmission 42 since this can be designed for the transmission of correspondingly lower drive torques and thus can be structurally more compact.

[0033] Furthermore, in a second section B, the modification on the part of the control unit 22 is performed such that the volume flow Q.sub.pump delivered by the variable-displacement pump 16 is adapted to maintain a predetermined power characteristic of the diesel engine 36. In this case, the volume flow Q.sub.pump delivered is reduced in an idling speed range or a range with a comparatively low speed of the diesel engine 36 to such an extent that possible stalling of the diesel engine 36 owing to excessive loading on the part of the variable-displacement pump 16 is prevented.

[0034] The terminology used herein is for the purpose of describing example embodiments or implementations and is not intended to be limiting of the disclosure. As used herein, the singular forms a, an, and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the any use of the terms has, includes, comprises, or the like, in this specification, identifies the presence of stated features, integers, steps, operations, elements, and/or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0035] Those having ordinary skill in the art will recognize that terms such as above, below, upward, downward, top, bottom, etc., are used descriptively for the figures, and do not represent limitations on the scope of the present disclosure, as defined by the appended claims. Furthermore, the teachings may be described herein in terms of functional and/or logical block components or various processing steps, which may include any number of hardware, software, and/or firmware components configured to perform the specified functions.

[0036] Terms of degree, such as generally, substantially, or approximately are understood by those having ordinary skill in the art to refer to reasonable ranges outside of a given value or orientation, for example, general tolerances or positional relationships associated with manufacturing, assembly, and use of the described embodiments or implementations.

[0037] As used herein, e.g., is utilized to non-exhaustively list examples and carries the same meaning as alternative illustrative phrases such as including, including, but not limited to, and including without limitation. Unless otherwise limited or modified, lists with elements that are separated by conjunctive terms (e.g., and) and that are also preceded by the phrase one or more of or at least one of indicate configurations or arrangements that potentially include individual elements of the list, or any combination thereof. For example, at least one of A, B, and C or one or more of A, B, and C indicates the possibilities of only A, only B, only C, or any combination of two or more of A, B, and C (e.g., A and B; B and C; A and C; or A, B, and C).

[0038] While the above describes example embodiments or implementations of the present disclosure, these descriptions should not be viewed in a restrictive or limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the appended claims.