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Patent Searching and Data


Title:
ENGINE SPEED CONTROL METHOD
Document Type and Number:
WIPO Patent Application WO/2009/145704
Kind Code:
A1
Abstract:
In a method and a system for controlling the set speed of an engine of a motorized vehicle equipped with a hydraulic device, the engine set speed is continuously determined in response to a speed demanded by the engine and a speed demanded by the hydraulic device.

Inventors:
SVENSSON MARTIN (SE)
BRAENNSTROEM ANDERS (SE)
Application Number:
PCT/SE2009/050566
Publication Date:
December 03, 2009
Filing Date:
May 19, 2009
Export Citation:
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Assignee:
SCANIA CV ABP (SE)
SVENSSON MARTIN (SE)
BRAENNSTROEM ANDERS (SE)
International Classes:
F02B67/08; B60K25/06; F02D29/04
Foreign References:
US6276449B12001-08-21
US6019702A2000-02-01
JP2001329883A2001-11-30
JP2001323827A2001-11-22
Other References:
See also references of EP 2288510A4
Attorney, Agent or Firm:
ELLIOT, Douglas (Södertälje, SE)
Download PDF:
Claims:

CLAIMS

1. A method of controlling the set speed of an engine of a motorized vehicle equipped with a hydraulic device, the hydraulic device being powered by a hydraulic pump powered by the engine, the method comprising the steps of: - determining an engine signal engine speed from at least one engine signal as an engine controlled speed,

- determining a hydraulic signal engine speed from a signal indicative of a current hydraulic flow as an hydraulic controlled speed, and

- continuously determining the set engine speed in response to the engine controlled speed and the hydraulic controlled speed, wherein the set engine speed is determined to be the highest of the engine controlled speed and the hydraulic controlled speed or a value related to the highest of the engine controlled speed and the hydraulic controlled speed.

2. The method according to claim 1 , wherein the hydraulic pump is a pump with fixed capacity.

3. The method according to claim 1 , wherein the hydraulic pump is a pump with pressure controlled capacity.

4. A controller for controlling the set speed of an engine of a motorized vehicle equipped with a hydraulic device, the hydraulic device being powered by a hydraulic pump powered by the engine, the controller comprising:

- means for determining an engine signal engine speed from at least one engine signal as an engine controlled speed,

- means for determining a hydraulic signal engine speed from a signal indicative of a current hydraulic flow as an hydraulic controlled speed, and

- means for continuously determining the set engine speed in response to the engine controlled speed and the hydraulic controlled speed, wherein the set

engine speed is determined to be the highest of the engine controlled speed and the hydraulic controlled speed.

5. A vehicle comprising a hydraulically powered bodywork powered by a hydraulic pump and the controller according to claim 4.

6. The vehicle according to claim 5, wherein the heavy vehicle is a truck equipped with a hydraulically powered crane.

7. The vehicle according to any of claims 5 or 6, wherein the hydraulic pump is a pump with fixed capacity.

8. The vehicle according to any of claims 5 or 6, wherein the hydraulic pump is a pump with pressure controlled capacity.

9. A computer program product for controlling the set speed of an engine of a motorized vehicle equipped with a hydraulic device, the hydraulic device being powered by a hydraulic pump powered by the engine, wherein the computer program product comprises program segments that when executed on a computer causes the computer to perform the steps of:

- determining an engine signal engine speed from at least one engine signal as an engine controlled speed,

- determining a hydraulic signal engine speed from a signal indicative of a current hydraulic flow as an hydraulic controlled speed, and - continuously determining the set engine speed in response to the engine controlled speed and the hydraulic controlled speed, wherein the set engine speed is determined to be the highest of the engine controlled speed and the hydraulic controlled speed.

10. A digital storage medium having the computer program product according to claim 9 stored thereon.

Description:

ENGINE SPEED CONTROL METHOD

TECHNICAL FIELD

The present invention relates to a method and an apparatus for controlling the engine speed of a heavy vehicle. In particular the present invention relates to a method and apparatus for controlling the engine speed of a heavy vehicle where the engine powers a hydraulic pump adapted to power a hydraulic device.

BACKGROUND

Heavy vehicles can in many cases be provided with a hydraulic system driving a hydraulic device built on or connected to the heavy vehicle. An example is a truck provided with a body work such as a hydraulically powered crane.

The engine of the heavy vehicle is adapted to power one or many hydraulic pumps which in turn generate a hydraulic flow that powers one or more hydraulic devices of the heavy vehicle. Conventional systems for controlling the engine typically strive to maintain a preset speed of the engine when the hydraulic device is used.

There is a constant desire to improve the performance of heavy vehicle and to reduce fuel consumption. Hence there exists a need for an improved engine speed control of a heavy vehicle provided with a hydraulically driven device.

SUMMARY

It is an object of the present invention to provide a method and a system that provides an improved engine speed control of a heavy vehicle provided with a hydraulically driven device.

This object and others are obtained by the method, device and computer program product as set out in the appended claims. Thus, in order to provide an efficient powering of a hydraulic device on a motorized vehicle, in particular a hydraulically powered bodywork of a truck such as a hydraulic crane, the engine speed is controlled in response to both a currently demanded engine speed as demanded by the engine and an engine speed demanded by the hydraulic device. In particular the engine set speed can be determined to be the highest of the engine speeds demanded by the engine and the hydraulic device or a an engine set speed related thereto.

Using the method and device in accordance with the present invention will provide an improved control of the engine speed of a motorized vehicle provided with a hydraulic device such as a truck provided with a crane or a front loader or any other motorized vehicle having an engine driving a hydraulic pump for powering a hydraulic device. Because the engine speed required for powering the vehicle is continuously monitored and updated there is no need to set the engine speed to an unnecessary high speed, which in turn reduces fuel consumption. Also the working environment is improved in that the engine noise is kept at a minimum.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail by way of non- limiting examples and with reference to the accompanying drawings, in which:

- Fig. 1a is a general view of a system for controlling the engine speed of a motor vehicle provided with a hydraulically driven device, and

- Fig. 2 is a flowchart illustrating steps performed when controlling the engine speed of a motor vehicle provided with a hydraulically driven device.

DETAILED DESCRIPTION

In Fig.1 a view of a system 100 for controlling the engine speed of an engine 105 powering a vehicle provided with a hydraulic device 103 is depicted. The system comprises a control module 109 for controlling the speed of the engine 105. The control module 109 is programmed to receive real time control signals from an engine controller 107 such as an Electronic Control Unit (ECU) provided signals indicative of a current engine operational conditions. The control module 109 is also connected to a controller 111 for controlling the hydraulic device 103. The controller 111 is adapted to control the hydraulic device in accordance with user input signals received from a user for example using a control device (not shown).

The control module 109 receives signals from the controller 111 indicative of a currently demanded engine speed to power the hydraulic device 103. In accordance with one embodiment the controller emits a signal indicative of the current demanded flow in the hydraulic device 103. In accordance with one embodiment the hydraulic pump powering the hydraulic device is a pump with fixed capacity not being possible to adjust. In another embodiment the hydraulic pump powering the hydraulic device is a pressure compensating variable pump having a pressure controlled capacity. The control module is then programmed to convert the demanded flow to a preset engine speed for example using a look-up table. In accordance with another embodiment the controller 111 is adapted to emit a signal indicative of a demanded engine speed required for the demanded flow in the hydraulic device.

- A -

Using the signals from the engine controller 107 and the hydraulic controller the control module continuously sets the engine speed in response to at least both signals from the engine and the hydraulic device. In accordance with one embodiment the engine speed is set to the highest of the engine speeds indicated by the engine controller signal and the hydraulic controller signal. For example if the signal from the engine controller indicates that the engine set speed should be 800 rpm and the demanded flow in the hydraulic device indicates that the engine set speed should be 900 rpm the controller module 109 sets the engine speed to the highest of the two, in this example the engine speed would be set to 900 rpm.

In Fig. 2 a flow chart illustrating some procedural steps performed when controlling the engine speed of motorized vehicle provided with a hydraulic device is shown. First in a step 201 an engine controlled engine speed as determined from engine signals is determined. Next in a step 203 a hydraulic controlled engine speed as determined from the currently requested flow in the hydraulic device is determined. Thereupon, the engine speed is set to a value in response to the engine speeds determined in steps 201 and 203. In particular the set value for the engine speed is set to the highest of the engine speeds determined in steps 201 and 203 or a value related to the highest value. Next, the procedure returns to step 201 to continuously update the engine speed in a step 207.

The control method as described herein can advantageously be computer implemented and the control algorithm can be stored as programmed instructions in a computer program stored on a digital storage medium.

Using the method and system as described herein will provide an improved control of the engine speed of a motorized vehicle provided with a hydraulic

device such as a truck provided with a crane or a front loader or any other motorized vehicle having an engine driving a hydraulic pump for powering a hydraulic device. Because the engine speed required for powering the vehicle is continuously monitored and updated there is no need to set the engine speed to an unnecessary high speed, which in turn reduces fuel consumption. Also the working environment is improved in that the engine noise is kept at a minimum.