This Application is a 35 USC § 371 US National Stage filing of International Application No. PCT/EP2015/052927 filed on Feb. 12, 2015, and claims priority under the Paris Convention to European Patent Application No. EP 14161139.2 filed on Mar. 21, 2014.
The present invention relates to the field of engine control systems, and in particular to a control process and system for controlling a speed governor of an engine.
A speed governor controls and adjusts the speed of an engine typically by controlling the amount of fuel supplied to the engine during operation. If the engine is to run at a faster speed more fuel is supplied, whilst less fuel is supplied if the engine speed is to be reduced. Governors are key components of engine control systems, particularly as engine manufacturers seek to develop more efficient engines.
In engine control systems, governors usually receive control signals from an engine controller. Engine controllers monitor numerous input and output parameters of an engine in order to ensure optimum performance of the engine. With the drive towards more and more efficient and economical engines, engine controllers are often now tasked with ensuring that engines are performing at optimum efficiency. This typically involves the engine controller being provided with one or more engine maps to ensure that the engine is operating as efficiently as possible. For example, the engine map may be a map of engine power versus engine speed to ensure that the engine produces a certain engine power at the lowest possible engine speed. The controller can then instruct the governor to adjust the engine speed so that the engine speed remains as low as possible for the required power, as defined by the engine map.
Whilst such control arrangements can improve the efficiency of an engine they have limitations when applied to engines in vehicles which have engine-powered ancillary systems and components, for example. In such vehicles demand for increased engine power from, for example, a hydraulic circuit controlling a tipper bed or bucket can lead to a delay in the increased power being delivered as the engine controller reacts to the demand. It can also mean that the efficiency of the engine is compromised as the controller tries to meet the twin targets of the engine efficiency map and the increased power demanded by the ancillary systems.
It is an aim of the present invention to obviate or mitigate this and other disadvantages with existing engine control systems and/or processes.
According to a first aspect of the invention there is provided a control process for controlling an engine speed governor of an engine, the process comprising the steps of:
According to a second aspect of the invention there is provided a speed governor system for an engine having at least one operator input, the system comprising:
A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompany drawings, which are as follows:
Also in two-way communication with the engine controller 10 is a supervisory controller, or systems controller, 16. The supervisory controller 16 receives data from a plurality of system sensors 18 which monitor various performance aspects of the vehicle within which the engine is mounted. For example, on certain agricultural and construction vehicles such as tractors and bucket loaders there are additional hydraulic systems such as power take off (PTO) units and hydraulic rams for operating buckets and the like. The system sensors 18 monitor the performance of aspects of these auxiliary systems. In addition, the supervisory controller 16 also receives data from at least one operator input sensor 20 which monitors operator control inputs such as, for example, via a throttle pedal or lever. The final component of the system is an engine speed governor 22 which is in two-way communication with the engine controller 10. The governor 22 can adjust the speed of the engine in response to control signals from the engine controller, usually by varying the rate of fuel delivery into the engine.
The controller is also continuously monitoring for signals from the supervisory controller 16 as regards data 109,111 received from the system and/or operator input sensors 18,20. Once the optimum engine speed has been determined at determination step 104 the controller then determines at step 106 whether any data 109,111 received indicates a need for additional power. If no additional power need is determined, a comparison of current engine speed and ideal engine speed in made at decision step 108. If the current speed matches the ideal speed, or is within acceptable limits (e.g. ±5%), the process will loop back to determination step 102. However, if the current engine speed does not match the ideal speed or is outside acceptable limits then the controller will instruct the governor to adjust the engine speed at decision step 110 before looping back to step 102.
If it is determined that additional power is needed at step 106 the controller will calculate the total power required to meet the request and determine a ratio of current power to that total desired power at determination step 112. At a subsequent determination step 114, the controller looks up data in an adjustment map 113 stored in the system memory in order to determine a speed adjustment value which should be sent to the engine governor in order to meet the total desired power value. The table below gives an example of such an adjustment map:
Based on the information in the adjustment map, the controller then instructs the governor to adjust the engine speed in accordance with the appropriate adjustment value.
Finally, the controller determines whether the engine is continuing to run at decision step 116. If the engine has stopped, the process stops at termination step 118. Alternatively, if the engine is still running the process proceeds to repeat step 120 and the process begins again with determination step 102.
An example of how the system and process of the present invention would work in practice will now be described.
It should be understood that the present invention could be applied to a wide variety of construction, agricultural and other heavy duty vehicles such as on-highway trucks and buses, agricultural tractors, off-highway trucks, construction and mining vehicles. However, in this preferred example the present invention is being applied to an off-highway articulated tipper truck for use in construction and mining activities, such as the applicant's CAT 725C truck. Such trucks are required to operate over a wide variety of terrain, both inclined and relatively flat, and also must deposit loads carried in their tipper beds at specified locations. A schematic view of such a truck is shown in
The truck 200 includes an internal combustion engine 202 which is arranged so as to provide motive force for the vehicle as well as powering certain ancillary systems. In this case the engine 202 also powers, amongst other things, the hydraulic system which operates the tipper bed 204. This system includes a pair of hydraulic rams 206, each of which has one end fixed to the truck chassis 208 and the other end attached to the tipper bed 204.
Monitoring various parameters of the engine 202 are a plurality of the engine sensors 12. The supervisory controller 16 monitors for desired power requests from an operator input sensor 20 attached to the throttle pedal 210 of the truck as well as ancillary system sensors 18 monitoring at least the hydraulic rams 206. The engine controller 10 is mounted to the engine 202 and is in communication with the engine sensors 12 and the supervisory controller 16. The speed governor 22 is located on or adjacent the engine so that it may control the flow rate of fuel into the engine in response to signals from the engine controller 10.
With the system as shown in
Once the minimum engine speed has been established the process will decide at decision step 106 whether a request for power has been received from the supervisory controller 16. Such a request would be made based upon data 109,111 received from either one or more of the system sensors 18 and/or the operator input sensor 20. In this example, such a power request may be received if a system sensor determines that additional hydraulic pressure is required to lift the tipper body 204, or if the operator input sensor 20 senses that the vehicle operator is making a manual input via the throttle pedal 210. Additionally, in certain applications where the truck is continually following a predetermined route it may be equipped with a global positioning satellite (GPS) enabled system which is programmed with data relating to the contours of the ground being covered and hence the location of any inclines, for example. In such applications the GPS system may indicate to the supervisory controller that an incline is approaching and the supervisory controller may request additional power from the engine controller.
In the event that no power requests are detected, decision step 108 will decide whether the current engine speed is the ideal engine speed based upon the determination made at step 104 based on the map data 105. If the current engine speed is the ideal speed, or within a predetermined range (e.g. ±5%), then the process will loop back to determination step 102. If the current speed is outside of the predetermined range then the controller instructs the governor to adjust the engine speed at process step 110 before the process loops back to step 102.
If additional power is requested based upon system sensor data or an operator input, then a ratio of the total desired power to the current power is determined at step 112. That ratio is then looked up in the speed adjustment map 113 and the engine speed is adjusted at step 114 based on the adjustment valve established from the map 113.
Finally, the process looks for an engine stop request by the truck operator at decision step 116, and either stops the process at termination step 118 or else beings to repeat the process from the beginning via step 120.
The system and process of the present invention ensure that the engine of a vehicle can be run at its most efficient (i.e. lowest) speed for a particular engine power. They also ensure that the engine reacts quickly to additional power demands which may be required for ancillary systems on the particular vehicle in which the engine is operating. However, during the periods of additional power demands the present invention ensures that the engine is still running at its optimum efficiency without running the engine at greater speeds (and fuel consumption) than necessary and without having to accelerate the engine quickly to generate more power due to an unexpected power demand from some system on the vehicle.
Modifications and improvements may be incorporated without departing from the scope of the invention.
Number | Date | Country | Kind |
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14161139 | Mar 2014 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2015/052927 | 2/12/2015 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2015/139889 | 9/24/2015 | WO | A |
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Number | Date | Country | |
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20170016405 A1 | Jan 2017 | US |