GB2353337A - Gearlever and controller with automatic switching between manual and automatic modes - Google Patents

Abstract

A lever arrangement 1, for a off road vehicle, includes a functional lever 3, eg a joy stick or slider, which is transiently displaced to manually select a shift in transmission combination/ratio which is sustained until a controller determines that an alternative ratio is required in order to provide best performance or mode of operation, eg hill ascent/descent. Thus driver selection of a particular transmission ratio is over-ridden and failure to de-select that ratio does not inhibit on-going vehicle operation to provide best performance determine by the controller. A display area 4 in which current vehicle operating functions are depicted, for example a transmission window 5 shows gear ratio or drive condition whilst a mode window displays a mode of vehicle operation required by the driver selected by a mode switch 7. Vehicle operating modes are selected by operational lever 2 which has operational positions which relate to automatic gearbox combinations, eg park, reverse, drive. The lever 3 may select two/four wheel drive, front/rear wheel drive, side to side wheel drive and/or high/low gear ranges.

Description

2353337 A Lever Arrangement The present invention relates to a lever

arrangement and more particularly to a transmission selection lever arrangement for use in an automatic transmission with switching between two wheel drive and four wheel drive or between a low gear ratio range and a high gear ratio range or other transmission gear 5 combination.

It is known to provide an automatic transmission in a motor vehicle which by its nature selects the most appropriate gear ratio combination for current driving conditions. Thus, less on going driver intervention is required so there may be improved driver comfort, safety and possibly better performance achieved for vehicle operation. Clearly, most automatic transmission arrangements also include a manual over-ride facility so that the driver can lock the vehicle transmission to particular gear ranges or drive characteristics.

In a normal automatic gear box there will be provided a drive position for the gear lever which is consistent with normal vehicle operation. However, there will also be provided a park position, a reverse position and lever positions consistent with transmission lock in first or second gear. Thus, the driver will be able to select the most appropriate position for expected driving requirements. Clearly, the transmission lever will be in the drive position mostly when the vehicle is being driven.

More recently, it has become relatively common to include automatic transmissions in off-road vehicles. Since, a wider range of gear ratios will generally be required in these off-road vehicles typically high and low gear ratio ranges will be provided. It will be understood these respective high and low gear ratio ranges act to alter to principal gear ratios of the automatic transmission so that there is sufficient torque range to allow the vehicle to be driven more easily off-road.

It will also be understood that off-road vehicles may include a facility to switch between two wheel drive and four wheel drive. Thus, typically a second lever will be provided to switch selection between the low and high ratio ranges operated by the driver along with between two wheel drive and four wheel drive. It will also be understood that there may be elective control over axle differentials such that they may be locked to specific relative ratios etc.

As automatic transmissions become more sophisticated it win be understood a controller device may be provided to relate the driver's requirements through lever position along with accelerator position compared to current engineltransmission stress etc. Clearly, in such circumstances, the controller may wish to utilise the full range of gear ratios available including those in both high and low gear ratio ranges. However, generally the setting of the high and low gear range lever may hmit those gear ratios available and the driver may forget to make the appropriate change. In any event, a requirement that the driver switches between high and low ranges along with two and four drive cannot be considered automatic control and may be cumbersome to the driver, particularly if the vehicle must be stopped to make the manual change.

Automatic gear selection arrangements are known which allow he driver to increment and decrement through primary gears in sequential order but with a controller ignoring individual selections if increments or decrements are made too quickly. Such selections are made using either a centre-sprung forward/back movement lever or respective +/- momentary action buttons. It is also common for the current gear to be displayed as the control lever position does not illustrate the current transmission system setting or restrict automatic changes. It will also be understood that such automatic gear selection arrangements may ignore gear change requests from the driver which an arrangement controller considers inappropriate. Furthermore, the selection arrangement may stimulate or trigger gear changes itself in order to avoid stalling or over-revving the engine.

With off-road vehicles it is known to provide controls in a transmission selection arrangement where there are a sequence of settings such as:- (a) Two wheel drive (Full time) - High range; (b) Four wheel drive (Part time) - High range; (c) Four wheel drive (Full time) - High range; (d) Neutral; and, (e) Four wheel drive (Full Time) - Low range.

Additionally, it is known with some off-road vehicles to provide one or more manually lockable and therefor elective differentials set separately or as an adjunct to selection of other operational features in the vehicle. However, some transmission transitions or combinations will not be physically feasible and so will not be allowed. Thus, the driver will either be warned of such unacceptable transition or combination such that the driver may attempt to 'force' such a transition or combination and be distracted in making these attempted transitions.

In any event, it will be appreciated that the control burden placed upon the driver of a vehicle can become excessive with the inherent reduction in efficient and safe operation of the vehicle.

It is an objective of the present invention to provide a gear lever arrangement which facilitates better incorporation with an automatic transmission of a motor vehicle.

In accordance with the present invention there is provided a lever arrangement for a motor vehicle, the arrangement comprising at least one lever coupled to a controller in order to determine vehicle transmission function, the or each lever being bias to a neutral operational position but transiently displaceable to activate a switch mechanism to change vehicle transmission combination but returned to the neutral position thereafter, the controller being configured to sustain that vehicle transmission combination selected by the or each lever until or unless that controller determines an alternative vehicle transmission combination is required.

The lever may be displaceable in two or more distinct directions to allow for both selection and de-selection of transmission settings.

Typically, the controller will be coupled to display means to indicate current transmission function. Furthermore, this display means win show when the transmission combination transiently selected by the lever is over-ridden by the controller.

Generally, the gear arrangement will have two levers, only one lever being biased to a neutral position whilst the other lever retains an operational position which continues to influence the controller dependent upon that position of the lever.

The vehicle transmission combination may be a high or a low gear ratio range selection or switching between two wheel drive and four wheel drive for a vehicle transmission power train. Clearly, the lever could be configured whereby in two wheel drive to four wheel drive switching the lever could select the power distribution between front and rear wheel at least transiently by manual displacement of the lever by the vehicle driver to the appropriate switch position and then return to the neutral operational position so that the vehicle transmission combination will continue as transiently indicated until the controller determines that an alternative power distribution between front and rear wheels or across the vehicle from side to side is required.

The lever may include a controller over-ride switch so that where required by the driver of a vehicle that vehicle transmission combination transiently selected by displa cement is retained despite the controller determining that an alternative vehicle transmission combination is more appropriate.

An embodiment of the present invention will be described by way of example only and reference to the accompanying drawings in which:- Figure I depicts a lever arrangement in schematic perspective view; and, Figure 2 is a block diagram of a typical sequence of transmission combination states for a lever arrangement.

Operation of an automatic transmission or gear box is well known to those skilled in the art. Thus, reference is made to that knowledge in order to understand and determine the scope of the present invention. It is also known to provide for vehicle transmission control through a controller configured to determine current operational conditions e.g. engine load, speed etc. and desired vehicle performance as determined by control settings e.g. accelerator pedal depression, gear lever position etc. Clearly, such a controller will be constrained if the full range of gear box or transmission configurations is not available such as if through the gear lever only one or limited part of the range of transmission functional combinations are available.

In accordance with the present invention a lever arrangement 1 as depicted in figure 1 is provided. Thus, generally two levers 2, 3 are arranged to control vehicle transmission function.

An operational lever 2 is configured to have operational positions which relate to commonly understood automatic transmission gear box combination positions. Thus, there is a position P for park, a position R for reverse, a position N for neutral or no drive gear engagement and an operational position D for normal driving function. It will also be understood that there may be positions such a denoted by a number 1 or 2 where the vehicle transmission may be locked in the lowest gears for continuous hill ascent or descent. The lever 2 will retain the operational position selected by the driver until altered by driver intervention so that the vehicle will be operated accordingly.

A functional gear lever 3 is also provided in accordance with the present invention. This lever 3 can be transiently displaced to a least one switch position but is biased back to its normal or neutral position after actuating a switch or other means to stimulate a particular vehicle transmission functional combination.

Thus, the lever 3 does not retain any position where it actively constrains or controls a vehicle transmission combination but depends upon a controller sustaining a transmission combination selected by that lever 3 after return of that lever 3 to the neutral position. In such circumstances, the driver can select a particular vehicle transmission combination through the lever 3 but the controller can determine from current or on-going operational parameters whether that transmission combination is the most appropriate to meet the other driver selected requirements determined through the lever 2 or other control devices such as the accelerator pedal.

A limitation with previous arrangements as described above was that once selected by an over-ride lever for low/high gear range or two/four wheel drive then that limitation continued until de-selected by the driver. Clearly, if the driver either forgot to make such a de-selection or was not sufficiently alert to make the de-selection in due time then severe strain can be placed upon the vehicle transmission. Transient selection of a transmission combination and then control logic sustain of that combination if appropriate by a controller ensures the present lever arrangement does not constitute a restraint upon efficient vehicle transmission operation or put undue stress on that transmission powertrain- It will be noted in figure 1 that a display area 4 is provided in which current vehicle operational functions are depicted for driver review. Thus, a transmission window 5 shows the gear ratio or drive condition of the vehicle whilst a mode window 6 displays the mode of vehicle operation required by the driver selected through a mode switch 7. Thus, a driver may wish to maximise fuel economy or maximise grip for off-road travel or to provide sporty responsiveness for acceleration etc. through the switch 7. The window 7 will show that current operational mode selection and the controller of the vehicle transmission will configure and operate that transmission to achieve the desired mode in relation to the operational position of the operational lever 2 whilst the preferred transmission combination transiently selected by the lever 3 will only be retained if consistent with the desired operational mode as determined by the controller.

It will be understood that the display area 4 may include advisory information 8 which suggests the most appropriate vehicle speed or other information for the current driving conditions and transmission combination selected or sustained by the lever 2, 3 as determined by the controller.

Further features selected by the lever 3 or other switches and controlled by the controller are for two wheel to four wheel drive switching and vice versa along with hill descent control through transmission engine braking and foundation brakes. Thus, a drive window 9 will show whether two or four wheel drive is selected by the lever 3. Furthermore, a graphic scale may show the power distribution between the front and rear wheels. A display symbol 10 will be illuminated to highlight that hill descent control has been selected.

Generally, it will be understood that the present invention allows a driver to specify the desired vehicle operational mode and performance through switching incorporated in the arrangement 1 but that a controller can over-ride at least some of those driver control settings in order to better achieve the desired operational mode. Thus, the lever 3 may switch initially to a particular transmission combination but if the controller does not determine that transmission combination is appropriate, or most appropriate, then an alternative transmission combination will be selected by the controller to best achieve the desired operational mode.

Clearly, fundamental switching is retained, such as that for drive or not through the lever 2 position D for drive and specific modes through switch 7. However, more discretionary transmission switching as set through the lever 3 is determined as a preferred operation rather than compulsory operation. Thus, the controller has more freedom to arrange specific vehicle transmission operation in order to meet the desired performance objectives and requirements of the driver.

The lever 3, as described previously, will be biased or sprung to a normal or neutral position in which normally no particular vehicle transmission combination is selected. Thus, after manual displacement by the driver to actuate a switch for a particular transmission functional combination, the lever 3 will return to its neutral or normal position with no on-going or active effect upon the transmission function. This normal or neutral position will typically be central between the respective switch positions for particular transmission combination operations. The controller will at least initially sustain the transmission combination corresponding to the transiently actuated switch made by the lever 3 but may subsequently ignore that transmission combination or select another more appropriate for continuing vehicle performance requirements. In such circumstances, it will be understood that there is no further driver action required to ensure that driver's specific or normal vehicle requirements are best achieved. The display area 4 simply shows current transmission combination status. Thus, it will be understood that the controller may ignore or reject a particular selection request made by the driver if that controller deems that request in appropriate for current or imminent conditions.

There will be occasion when the driver of a vehicle will wish to override the controller in order to provide for unusual vehicle operation or to anticipated performance requirements. Clearly, as with any control regime, there will be a time delay in adjusting transmission combination operation so that the vehicle may not be responsive enough at least in the short term. Thus, an over-ride switch can be provided with the lever 3 so that when that over-ride switch is selected then the controller is prevented or at least inhibited for a longer time period from ignoring the transmission combination selected by the lever 3. Alternatively, such over-ride could be provided by a consecutive and repeated double actuation of a particular transmission combination through its switch by the lever 3 or sustained displacement from the neutral position. In any event, such over-ride or inhibition of the controller ignoring the transmission combination selection may prevent hunting and short term changes in the transmission for transient changes in vehicle operational conditions.

The lever 3 can take the form of a joy stick type arrangement as illustrated in the drawing or a straight line slider arrangement with step ratchet between positions and/or an actuator button to select that switch position for the transmission combination required. Clearly, in either arrangement the functional lever will return to a normal or neutral position where a transmission combination is not selected through a respective switch.

In figure 2 a block diagram is depicted in which a sequence of transmission combination states are shown with allowable transitions between adjacent states.

Each transmission state is a combination of transmission settings of specific features however, it will be understood that the displaceable control lever may also in some embodiments only influence the setting of one transmission feature to select a transmission combination.

The lever can be transiently displaced in two distinct directions (forward and backward relative to a central neutral position) in order to allow selection, sequentially, of transmission combinations in either direction in the block diagram. Alternatively, it will be understood that a one directional lever displacement arrangement could be provided.

As indicated previously, automatic transmission transitions may be triggered, or manual transition requests may be ignored or refused depending upon transmission status, vehicle speed or other criteria. In any event, it will. be understood that the burden upon the vehicle driver is significantly reduced to simple transient displacement of a control lever to provide an indication as to desired operational performance and that indication is translated by the transmission controller in order to stimulate the appropriate transmission combination for current operational conditions. Clearly, with such a sequential selection regime it will be necessary for the driver to increment or decrement as required but such selection is a simple operation and easily performed with little distraction.

Although in figure 2 the transmission combination states are defined by only four features i.e. 2/4 wheel drive, high/low gear range, centre differential status and rear differential status, it will be understood that other transmission features could be defined as part of each transmission combination selected by the lever.

Clearly, lever displacements for the end transmission combination states are such that respective further either forward displacement for one end state and rearward displacement for the other end state has no effect. Thus, the lever has a linear control path between transmission combination states and is not a control loop where the lever can select transmission combination state at the ends and therefor most different transmission state without passing iteratively through the intermediate transmission combination states. In such circumstances, a vehicle transmission should not be subjected to severe shock loading and stress so that maintenance, durability and reliability should be improved.

Claims (10)

1. -12CLAIMS

   A lever arrangement for a motor vehicle, the arrangement comprising at least one lever coupled to a controller in order to determine vehicle transmission function, at least gear lever being configured with bias to a neutral operational position but transiently displaceable to activate a switch mechanism to change vehicle transmission combination but returned to the neutral position thereafter, the controller being configured to continue that vehicle transmission combination selected by the at least one lever until that controller determines an alternative vehicle transmission combination is required.
2. 2. An arrangement as claimed in claim I wherein the controller is coupled to display means whereby the current transmission combination is displayed.
3. 3. An arrangement as claimed in claim 2 wherein the controller is arranged to display through the display means when the transmission combination transiently selected by the lever is determined as not appropriate by the controller and that as such an alternative vehicle transmission combination is required.
4. 4. An arrangement as claimed in any of claims 1, 2 or 3 wherein the arrangement includes two levers, a functional lever which is biased to a neutral position and which can transiently select a particular vehicle transmission combination whilst an operational lever retains its operational position in order to continue to influence the controller in determination of the transmission combination required dependent upon that retained operational position.
5. 5. An arrangement as claimed in claim 4 wherein the functional lever is arranged to transiently select switching between two wheel drive and four wheel drive and vice versa.
6. 6. An arrangement as claimed in claim 5 wherein the functional lever is configured to allow transient selection of the respective power distribution between front and rear wheels of a motor vehicle and/or side to side across an axle, in use.
7. 7. An arrangement as claimed in claim 4 and any claim dependent there on wherein the functional lever is configured to allow transient selection between low gear range and a high gear range.
8. 8. An arrangement as claimed in any preceding claim wherein the lever is of joy stick type or a slider type with ratchet movement between switch positions with an actuator button for selection of vehicle transmission function.
9. 9. An arrangement as claimed in any preceding claim wherein the lever incorporates an over-ride switch whereby determination and/or selection of an alternative vehicle transmission combination by the controller is inhibited or at least delayed for a predetermined time period in order to prevent iterative changes to the transmission combination for short term operational vehicle variations.
10. 10. A lever arrangement substantially as hereinbefore described with reference to the accompanying drawing.