GB2345523A

GB2345523A - Movement control arrangement for a motor vehicle

Info

Publication number: GB2345523A
Application number: GB9900244A
Authority: GB
Inventors: Michael Neil Basnett; David Robert Cox
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1999-01-08
Filing date: 1999-01-08
Publication date: 2000-07-12
Also published as: GB9900244D0

Abstract

A movement control arrangement in which free movement of a motor vehicle is determined by a combination of a controller sensing movement that is not precipitated by the vehicle power unit and so limiting this free movement to an acceptable rate by proportional application of braking to the vehicle. Typically, the movement control arrangement utilises existing sensors used for traction and braking control along with the service or parking brake mechanisms in order to apply the proportional braking to the vehicle to restrict the speed of such free movement, and may be activated by obstacle proximity sensors.

Description

MOVEMENT CONTROL ARRANGEMENT The present invention relates to a movement control arrangement for a motor vehicle.

It will be appreciated that manoeuvring on a slope, particularly when reversing, can be hazardous. Furthermore, it is not uncommon for the driver, whilst facing backwards, to miss or be confused with regard to operations of vehicle control such as pedals and in such circumstances the vehicle may roll away. Upon steep inclines such roll away may precipitate a significant speed build up further adding to driver confusion and anxiety. Additionally, it will be appreciated that a motor vehicle driver may use a slope to move their vehicle without switching on the engine or out of gear or in an appropriate gear or for the engine to stall or, as indicated above, for the engine not to be operational with the potential loss of servo assistance for steering/braking.

Problems are particularly serious with regard to inexperienced, nervous or elderly drivers, and clearly when there is a significant vehicle speed build up can result in damage to the vehicle and even injury.

It is an object of the present invention to provide a movement control arrangement for a motor vehicle which avoids or significantly diminishes the above-mentioned problems.

In accordance with the present invention there is provided a movement control arrangement for a vehicle, the arrangement comprising means to determine free movement of a vehicle and means to apply proportional braking to that vehicle to restrict such free movement to an acceptable speed.

Typically, the means to determine free movement will include appropriate sensors to determine one or more of the following: a) the vehicle is not in gear and movement is sensed; b) a gear is engaged but the vehicle is moving in an opposite direction; c) the engine or power unit is deactivated/stopped but vehicle movement is determined; d) the vehicle is in gear, but the clutch is fully disengaged and movement is detected; and e) low or insignificant vacuum servo assistance is sensed but vehicle movement is determined.

The proportional braking of the vehicle may be provided through an existing anti-lock braking system of the vehicle or through other electrical braking mechanisms where the braking force/torque can be varied as required by a control device responsive to various operational parameters such as traction, vehicle speed, etc.

The means for determining free movement of the vehicle may include sensors associated with the wheels to determine rotation thereof and/or accelerometers associated with existing vehicle systems.

The acceptable speed of free movement may be varied incrementally between predetermined rates. Furthermore, the acceptable rate of free movement may be differential between forward and rearward motions and/or between uphill and downhill movements upon a slope and/or different slope gradients. In such circumstances, the movement control arrangement will also incorporate appropriate sensing means to determine forward/rearward motion and/or uphill/downhill motion and/or slope gradient. Typically, an acceptable rate of free movement will be between 1 and 2 km per hour.

An embodiment of the present invention will now be described by way of example only.

Braking systems within motor vehicles generally allow proportional braking in order to diminish vehicle speed. In such circumstances, the braking pressure/torque applied to restrict vehicle movement is simply increased until the appropriate drag is provided to restrict vehicle movements. This increase in braking pressure can be provided through a manually controlled brake pedal or through a vehicle controller mechanism to facilitate antilock braking and/or traction control for the vehicle. The present invention utilises such a controller within a vehicle in order that free movement of the vehicle can be restricted to an acceptable speed for safety purposes.

In order to be effective, such controller mechanisms within a vehicle must be associated with sensors determining vehicle operational conditions. Thus, typically a motor vehicle will include wheel sensors to determine wheel speed along with other sensors such as accelerometers. In any event, such sensing means within a vehicle can determine movement. In accordance with the present invention, the controller is also associated with sensors or other means of indicating vehicle operational conditions to determine whether that movement is of a free type as a result of the vehicle being on a gradient rather than driven movement as a result of engine/power unit operation. In any event, the controller will determine movement and then whether that movement is of a free type in order that the braking mechanisms of the vehicle will be activated in order to provide a proportional braking of the vehicle to restrict such free movement to that acceptable for current vehicle conditions. The controller in determining whether there is free movement will principally receive indications whether a gear has been engaged or the engine is operational or whether there is adequate vacuum servo assistance for steering/braking, etc.

Clearly, upon flat ground, the potential for free movement of the vehicle is limited. Thus, the present invention has particular applicability with regard to movement of a vehicle upon a slope. In such circumstances, as described previously, it is possible for a vehicle driver to attempt to manoeuvre utilising the slope. However, as the motive force ie gravity is not directly under the control of the driver, it will be appreciated that the potential for runaway is ever present in such movement. Thus, upon steep slopes and gradients, should the driver take the vehicle out of gear or choose an inappropriate gear or the engine stalls with potential loss of servo assistance for steering/braking, it is possible that a vehicle speed could rapidly increase. Particularly with regard to reversing, it is possible for the driver to depress the clutch pedal and thus disengage the gear inadvertently precipitating a runaway effect. With regard to inexperienced, nervous or elderly drivers, such rapid increase in speed may lead to confusion and/or panic such that a vehicle collision accident may occur with associated damage to the vehicle and personal injury to the vehicle occupants and any pedestrians, etc, thereabout.

The present invention provides a movement control arrangement where free movement is limited to an acceptable rate. Typically, this rate of vehicle movement or speed will be very low and set to a maximum in the order of 1 to 2 km per hour. Clearly, when driven movement is required, the present movement control arrangement will be deactivated in that such driven movement will inherently provide greater control to the vehicle driver as it requires positive action by that driver, ie. depression of the accelerator pedal, etc.

It will be understood that such a low maximum free movement, speed or rate may not be acceptable for all conditions. Thus, the present movement control arrangement will typically allow a range of incremental rates of such free movement dependent upon vehicle conditions. Thus, for example, the vehicle driver may be able to switch between an urban rate which is relatively low due to the inherently greater prospect of collision in such an urban environment in comparison with more open spaces found in rural areas. Furthermore, as indicated above, vehicle drivers can become more confused when reversing and so a differential between the acceptable rate of free movement in a forward direction in comparison with a rearward motion may be provided in the movement control arrangement. Similarly, a differential between uphill and downhill manoeuvres may be provided. However, it will be understood that typically uphill movement of a vehicle will be of a driven type and so when occurring will normally be the result of over run momentum, etc.

In order for the controller to provide means to determine free movement, it is necessary for a sensor such as that of an ABS system to show movement and then sensors attached to the gear mechanism/power unit and/or vacuum servo assistance system to determine that undriven free movement of the vehicle is occurring. Upon such determination, the movement control arrangement through a controller will instruct means to apply proportional braking to the vehicle in order to restrict such free movement to an acceptable rate for safety purposes. In such circumstances, the vehicle driver will still be able to manoeuvre the vehicle in terms of steering, but the rate of movement will be limited to the relatively low speed acceptable for safety purposes. Clearly, once vehicle motion and movement is driven and therefore generally more controlled by the vehicle driver, the movement control arrangement will deactivate the means to apply proportional braking in order that the vehicle may be normally driven. Thus, the application of proportional braking may be deactivated in the following circumstances: a) when a gear is engaged, the clutch moves from a fully disengaged position and movement is sensed in the correct direction for gear engaged; b) when the controller determines vehicle movement has reached a predetermined speed or rate inherent of driven action by a vehicle power unit; c) a deactivating switch or other device is thrown by a deliberate vehicle driver action. However, typically this deactivating switch will be located out of reach of the driver when normally seated to ensure deactivation of the present movement control arrangement does not happen when inappropriate. Typically, the present movement control arrangement would be deactivated to allow movement of the vehicle when it is being towed or serviced using a rolling road, etc.

Typically, within a vehicle, there is a so-called service brake used in normal vehicle operations and a parking brake used to hold the vehicle when not in use.

As it is inherent with the present invention that relatively low speeds will be used as an acceptable rate for free movement and typically such free movement will originate from a substantially standstill, it will be understood that either the service brake or the parking brake mechanisms could be utilised to apply the proportional braking to the vehicle-necessary to restrict such free movement to an acceptable speed for safety purposes either independently or in cooperation.

Where the present movement control arrangement is used in a situation where the vehicle is in gear but the clutch is fully disengaged whilst free movement is detected, it will be appreciated that operation of the arrangement may be limited to below certain vehicle speeds and/or only when an increase in speed from a standstill or very low speed is detected in order to avoid the present movement control arrangement being activated during periods of overrun free wheeling, normal gear changing, etc for the vehicle. Similarly, when the present movement control arrangement is activated due to inadequate vacuum servo assistance for steering or braking, it will be understood that such activation will typically be limited to below a certain speed in order to avoid inadvertent proportional braking of a vehicle when not required.

It will be appreciated that within vehicles that include sensors for obstacle proximity determination that the present movement control arrangement could either be activated when an obstacle is detected within a certain range or the acceptable rate of movement for the vehicle could be reduced, possibly incrementally, using the present movement control arrangement as the vehicle gets nearer to that detected obstacle. In such circumstances, the possibility of collision is diminished and, in any event, the severity of such collision, will clearly be reduced by the lower vehicle approach speed provided by the present movement control arrangement.

Claims

CLAIMS 1. A movement control arrangement for a vehicle, the arrangement comprising means to determine free movement of a vehicle and means to apply proportional braking to that vehicle to restrict such free movement to an acceptable speed.
2. An arrangement as claimed in Claim 1, wherein the means to determine free movement determines one or more of the following: a) that the vehicle is not in gear, but movement is sensed by appropriate sensing means; b) a gear is engaged but the vehicle is moving in an opposite direction to that provided by the engaged gear, such vehicle movement being determined by appropriate sensing means; c) the vehicle power unit is deactivated but vehicle movement is sensed by appropriate sensor means; d) a gear is selected but a clutch is fully disengaged such that there is no driven movement by the vehicle, but movement is still detected by appropriate sensing means; and e) the level of vacuum or other servo assistance provided to vehicle steering and/or braking mechanisms is below a level predetermined by appropriate sensing means.
3. An arrangement as claimed in Claim 1 or Claim 2, wherein the means to apply proportional braking to the vehicle utilises the normal driving service brakes and/or the parking brake mechanism of the vehicle.
4. An arrangement as claimed in Claim 1,2 or 3, wherein the means to determine free movement of the vehicle include sensors to determine rotation of at least one vehicle wheel and/or accelerometers indicative of variation in vehicle movement.
5. An arrangement as claimed in any preceding claim, wherein the acceptable rate of free movement is variable dependent upon vehicle operational conditions.
6. An arrangement as claimed in Claim 5, wherein the acceptable rates of free movement are variable between predetermined incremental rates.
7. An arrangement as claimed in Claim 5 or Claim 6, wherein the acceptable rate of free movement for the vehicle is differential between forward and reverse movement of that vehicle.
8. An arrangement as claimed in Claim 5,6 or 7, wherein the acceptable rates of free movement for the vehicle are differential between uphill and downhill movement of that vehicle.
9. An arrangement as claimed in any of Claims 5 to 8, wherein the acceptable rate of free movement for the vehicle is variable dependent upon the severity of gradient or slope upon which vehicle is operationally located.
10. An arrangement as claimed in any preceding claim, wherein the arrangement includes a proximity sensor, such that as the vehicle approaches an obstacle the proximity sensor stimulates the control arrangement such that the acceptable rate of free movement for the vehicle is adjusted to diminish and/or facilitate avoidance of collision with that obstacle.
11. An arrangement as claimed in any preceding claim, wherein the acceptable rate of free movement for the vehicle is in the range of 1 to 2 km per hour.
12. A movement control arrangement substantially as hereinbefore described.