GB2397138A

GB2397138A - A method of controlling an internal combustion engine of a vehicle

Info

Publication number: GB2397138A
Application number: GB0400191A
Authority: GB
Inventors: Andrew Wicks
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2003-01-08
Filing date: 2004-01-07
Publication date: 2004-07-14
Also published as: GB0400191D0; GB0300375D0

Abstract

An internal combustion engine (11) has auxiliary engine devices (12-14) which consume engine power when in use. In a method of control of the engine (11), the power consumptions of the auxiliary devices (12-14) are controlled between Maximum and Minimum thresholds, depending upon vehicle engine operating conditions. Preferably, the engine power consumed by said devices (12-14) is increased during conditions of vehicle deceleration or overrun and is reduced during vehicle acceleration and cruise. An engine control module (ECM 16) controls the operation of the engine and is connected to a plurality of sensors (17-19) for monitoring vehicle and engine operating conditions, the ECM being programmed to control the power consumptions of the auxiliary devices (12-14) depending upon sensed conditions.

Description

A Method of controlling an Internal Combustion Engine of a Vehicle This

invention relates to a method of controlling an internal combustion engine of a vehicle and is particularly useful in relation to controlling the engines of motor cars.

Modern motor vehicles are typically provided with auxiliary engine devices such as alternators, air conditioning compressors, pumps etc. which consume engine power or torque on demand. The engine power consumed by the auxiliary devices usually continues when the vehicle is accelerating or cruising which means that the engine power absorbed by said devices during the acceleration and cruise modes causes a fuel economy penalty and a reduction in vehicle performance.

The present invention provides a method of control of the vehicle which ameliorates the effects of the power requirements of auxiliary engine devices.

According to a first aspect of the present invention there is provided a method of control of a vehicle internal combustion engine having an auxiliary engine device which consumes engine power when in use, wherein in said method the engine power consumption of the auxiliary device is varied between a minimum and a maximum depending upon vehicle and engine operating conditions.

Preferably, the engine power consumption of the auxiliary device is increased during conditions of vehicle deceleration or overrun and is reduced during vehicle acceleration and cruise.

Auxiliary engine devices comprise electrical and mechanical pumps driven off the engine, air conditioning compressors, alternators, air suspension pumps, mechanical vacuum pumps, pumps for power hydraulic circuits etc. The engine power consumption of the auxiliary device may be controlled by varying its output, e.g. the current output of an alternator, or by varying the drive ratio between the engine and the device.

The vehicle engine is preferably controlled by an ECM (engine control module) which also controls the engine power consumption of the auxiliary device to vary said consumption depending upon vehicle and engine operating conditions. Preferably, the ECM controls the engine power consumption of the auxiliary device so as to maintain optimum vehicle performance.

Conveniently, under low engine load and overrun conditions the engine power consumption of the auxiliary device would be at a maximum, whereas at higher engine loads the engine power consumption of the auxiliary device may be at a level which is less than the maximum level and which provides acceptable performance of the device and optimum fuel economy for the vehicle.

The ECM may constantly monitor a plurality of engine and vehicle conditions and constantly review the engine power consumption of the auxiliary device in accordance with the monitored conditions.

There may be a plurality of auxiliary devices, some or all of which are controlled by the 1 5 method.

The present invention also provides, according to a second aspect thereof, an internal combustion engine having an ECM which controls the operation of the engine and which is connected to a plurality of sensors for monitoring vehicle and engine operating conditions, the engine having an auxiliary engine device driven by the engine, wherein the ECM is programmed to control the power consumption of the auxiliary device in accordance with a method according to said one aspect The ECM may be connected to a control module for at least one auxiliary device.

The invention will be described by way of example and with reference to the accompanying drawings, of which: Fig.1 is a schematic drawing of a vehicle engine operated in accordance with the present invention; and Fig. 2 is a logic flow diagram showing the steps of the method according to the present invention.

With reference to Fig.1 there is shown an internal combustion engine 11 of a vehicle, in particular a motor car, having at least one auxiliary device and, typically, a plurality of auxiliary devices 12-14 driven by the engine, typically through respective belts driven by a pulley attached to the end of the engine crankshaft. The number and type of auxiliary devices will depend upon the vehicle requirements and may comprise, but is not limited to, the following examples:- air conditioning compressor, alternator, vacuum pump, hydraulic pump and air suspension pump. Preferably all of such devices would be controlled in accordance with this invention but for reasons of practicality or cost not all devices may be so controlled.

The engine operation is controlled by an electronically programmable electronic control module or ECM 16. The ECM 16 is connected to plurality of vehicle operating condition and engine condition sensors, represented by sensors 17-19. The sensors may include but are not limited to the following examples:- an engine speed sensor, engine torque output sensor, an engine torque demand sensor, a vehicle speed sensor, gear position sensor, engine temperature sensors, ambient air temperature sensor, oil temperature sensor, air intake volume sensor, torque converter slip sensor. The ECM 16 is connected to each auxiliary device 12-14, either directly as shown for device 14 or through a respective device control module 21, 22, as shown for the auxiliary devices 12 and 13.

The ECM 16 is pre-programmed with information relating to the engine power consumption of the respective auxiliary devices under different operating conditions as these relate to the output requirements of each device. This information may be programmed in the form of look-up tables or algorithms derived from empirical data. The (A ECM 16 is also pre- programmed with information relating to the maximum and minimum limits of the outputs of the respective auxiliary devices 12-14. These parameters will be based on perceived satisfactory performance of the respective device 12-14 under various operating conditions and with regard to the durability of the device.

The ECM 16 is also pre-programmed with information relating to optimum engine performance at different engine torque output requirements under various service conditions (so-called engine mapping) and is also programmed so that the torque requirements for the various auxiliary devices 12-14 are matched with the vehicle engine torque output.

In operation and with further reference to Fig.2, the ECM 16 at STEP A calculates the desired output and hence engine power consumption of the auxiliary devices 12-14.

STEP B determines if these requirements fall within the maximum and minimum parameters for said outputs.

The ECM 16 monitors the current vehicle and engine operating conditions through the various sensors 17-19 at STEP C and at STEP D determines the optimum torque requirements of the auxiliary devices 12-14 in accordance with vehicle operating conditions, e.g., vehicle accelerating, cruising, or decelerating (in overrun).

The ECM 16 then controls the required output from each auxiliary device 12-14 at STEP E, either directly or through its respective control module 21, 22, in order to match the output and torque requirements to the engine operation and thereby vary the engine power consumption of the auxiliary device between a minimum and a maximum depending upon vehicle and engine operating conditions. The outputs from the auxiliary devices 12-14 are controlled to increase during conditions of vehicle deceleration or overrun, and reduce during vehicle acceleration and cruise. Under low engine load and overrun conditions the auxiliary devices 12-14 could be driven at maximum demand. The variation - 5 in the demand and hence the engine power consumption of the auxiliary device 12- 14 could be continuous (preferable) or in steps according to the type of device and the control methods available. )

Claims

1. A method of control of a vehicle internal combustion engine having an auxiliary engine device which consumes engine power when in use, wherein in said method the engine power consumption of the auxiliary device is varied between a minimum and a maximum depending upon vehicle and engine operating conditions.

2. A method as claimed in Claim 1 wherein the engine power consumption of the auxiliary device is increased during conditions of vehicle deceleration or overrun and is reduced during vehicle acceleration and cruise.

3. A method as claimed in Claim 1 or Claim 2, wherein the vehicle engine is controlled by an engine control module (ECM) which also controls the engine power consumption of the auxiliary device to vary said consumption depending upon vehicle and engine operating conditions.

4. A method as claimed in Claim 3, wherein the ECM controls the engine power consumption of the auxiliary device so as to maintain optimum vehicle performance.

5. A method as claimed in any one of Claims 1 to 4, wherein under low engine load and overrun conditions the engine power consumption of the auxiliary device would be at a maximum.

6. A method as claimed in any one of Claims 1 to 5, wherein at higher engine loads the engine power consumption of the auxiliary device would be at a level which is less than the maximum level and which provides acceptable performance of the device and optimum fuel economy for the vehicle.

7. A method as claimed in Claim 3 or Claim 4 or any claim dependent therefrom, wherein the ECM constantly monitors a plurality of engine and vehicle conditions and

- )

constantly reviews the engine power consumption of the auxiliary device in accordance with the monitored conditions.

8. A method as claimed in any preceding claim wherein there is a plurality of said auxiliary devices 8. An internal combustion engine having an ECM which controls the operation of the engine and which is connected to a plurality of sensors for monitoring vehicle and engine operating conditions, the engine having an auxiliary engine device driven by the engine, wherein the ECM is programmed to control the power consumption of the auxiliary device in accordance with a method as clamed in any of claims 1 to 7.

9. An engine as claimed in Claim 8, wherein the ECM is connected to a control module for at least one auxiliary device.