DE112016005907B4 - System for providing four-wheel drive in a vehicle - Google Patents

Abstract

A system (3) for providing four-wheel drive in a vehicle (1), the system (3) comprising;
a power transmission means (5) comprising a gear arrangement (51) and at least one clutch (53, 55), the power transmission means (5) being arranged to receive an output power from an engine (15) and being arranged to transmit power from the engine (15) via the gear arrangement (51) and the at least one clutch (53, 55) to provide a first output power at a first gear ratio to drive two wheels (11) on a first axle (13), the at least one clutch (53, 55) being arranged between the engine (15) and the gear arrangement (51);
a transmission means (7) arranged to receive the output of the engine (15) via a propeller shaft (18);
wherein the transmission means (7) is arranged to transmit power from the engine (15) to drive two wheels (19) on a second axle (9);
wherein the at least one clutch (53, 55) is configured to slip when the ratio of engine speed to wheel speed of at least one wheel (19) on the second axle (9) does not match the ratio of engine speed to wheel speed of at least one wheel (11) on the first axle (13).

Description

TECHNICAL AREA

The present disclosure relates to a system for providing four-wheel drive in a vehicle. More particularly, but not exclusively, it relates to a system for providing four-wheel drive in a vehicle having a rear transaxle.

Aspects of the invention relate to a system, a power transmission means and a vehicle.

STATE OF THE ART

In rear transaxle vehicles where the engine is mounted at the front of the vehicle and the transmission is mounted at the rear, a propeller shaft is provided to connect the engine to the transmission. It is necessary to connect the front wheels to the transmission to provide power to enable four-wheel drive. This requires a second propeller shaft to couple the transmission to the front axles. This additional propeller shaft is undesirable as it reduces the efficiency of the vehicle and also increases the cost and weight of the vehicle.

Further state of the art EN 11 2013 004 889 T5 , DE 21 35 791 A , JP 2006- 117 084 A , and US 2005 / 0 224 262 A1 .

It is an object of the present invention to address disadvantages associated with such systems.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide systems, transfer cases and vehicles according to the appended claims.

According to one aspect of the invention there is provided a system for providing four-wheel drive in a vehicle, the system comprising: a power transmission means arranged to receive an input power of an engine and arranged to transmit input power from the engine via a first output power for driving two wheels on a first axle; wherein the input power of the engine is additionally provided as a second output power of the power transmission means to a transmission means via the propeller shaft; wherein the transmission means is arranged to transmit power from the engine for driving two wheels on a second axle.

Since the power transmission means is arranged to be coupled to the engine rather than to the transmission means, the need for a second transmission shaft between the transmission means and the two wheels on the first axle is removed. This can increase the efficiency of the vehicle. It can also reduce the cost and weight of the vehicle.

By arranging the power transmission means to be coupled to the engine rather than the transmission means, it is possible for the power transmission means to be provided towards the front of the vehicle. This can improve the design freedom for the floor of the vehicle. It can provide increased space for footwells in the vehicle. It can also enable a generic floor design to be used in both four-wheel drive and rear-wheel drive vehicles. This could also reduce the cost of the vehicle.

The power transmitting means comprises a gear arrangement and at least one clutch positioned between the engine and the gear arrangement. The gear arrangement and the at least one clutch may be configured to enable the power transmitting means to provide the first output power at a plurality of different first output power speeds for driving the two wheels on the first axle. The transmission means may comprise a plurality of gears and the gears may be arranged to provide transmission drive at a plurality of different transmission drive speeds for driving the two wheels on the second axle.

Since the power transmission means allows the two wheels on the first axle to operate at different speeds, this may enable four-wheel drive of the vehicle to be provided in different gears of the transmission means. This may enable four-wheel drive of the vehicle in high gears of the transmission means as well as in low gears of the transmission means.

The transmission means may be a gearbox and the power transmission means may be a transfer case.

The gear arrangement and the one or more clutches may be arranged such that the plurality of different output power speeds of the power transmission means with the plurality of different transmission output speeds of the transmission means. The correlation of the plurality of first output speeds of the power transmission means and the plurality of transmission output speeds of the transmission means may enable the first output speed of the power transmission means to match the transmission output speed of the transmission means.

The power transmitting means may be provided such that when the transmission means is in a first subset of gears, the power transmitting means provides the first output power speed at a first speed and when the transmission means is in a second, different subset of gears, the power transmitting means provides the first output power speed at a second, different speed.

The gear arrangement and at least one clutch may be configured such that when the transmission means is in a third, different subset of gears, the power transmitting means provides the first output power speed at a third, different speed.

Having at least three different speeds provides a multi-stage power transmission means capable of providing output powers at a plurality of different speeds. This may enable the speed of the power transmission means to match the speed of the transmission means for a large number of gears. This may enable four-wheel drive of the vehicle in both low gears and higher gears of the transmission means.

The input power to the power transmission means can rotate at the engine power speed.

By arranging the power transmitting means to be coupled to the engine rather than the transmission means, it is possible for the input power to be provided to the power transmitting means at the engine power speed rather than the transmission means power speed. This may enable the power transmitting means to provide output powers when the transmission means is in a higher gear.

The power transmission means may include a plurality of clutches configured to enable different gear arrangements to be connected.

By having a plurality of clutches, one or more gear arrangements may be enabled to be connected and/or disconnected. This allows a plurality of different first output power speeds to be provided by the power transmission means, thus enabling the compliance with a plurality of subsets of gears from the transmission means.

At least one of the clutches can disconnect the gear assembly from the input power from the engine and the two wheels on the first axle such that the two wheels on the first axle are coupled to the input power from the engine.

This enables one-to-one switching between the input power of the engine and the first output power of the power transmission means. This may enable the first output power speed of the power transmission means to closely match the transmission output power of the transmission means when the transmission means is in higher gears.

The couplings may include slip couplings.

The slippable clutches may be arranged such that the first output power speed of the power transmission means may be adapted to more than one gear of the transmission means when the gear arrangement is connected. This enables the power transmission means to use fewer gears than the transmission means because a single gear of the power transmission means may be adapted to the transmission means.

The gears in the gear arrangement include planetary gears.

The planetary gears may be arranged such that interconnection of different stages of the planetary gears enables different first output power speeds to be provided by the power transmission means.

The system may comprise a control device configured to determine the current gear of the transmission means and to send a control signal to the power transmission means which indicates the current gear of the transmission.

This allows the speed of the power transmission means to be matched to the speed of the gear of the transmission means. Using the current gear of the transmission means, a simple input can be provided to control the output of the power transmission means. This can be simpler than monitoring multiple inputs from multiple sensors.

The vehicle may be a rear transaxle vehicle.

With the engine at the front and the transmission at the rear, a good weight distribution can be provided in the vehicle.

The power transmission means may be arranged to be coupled to the rear of the engine.

This provides improved weight distribution as the weight is added behind the engine rather than at the front of the vehicle. This can prevent the vehicle from becoming too heavy at the front.

The power transmission means may include an electric motor configured to control the position of a clutch.

The electric motor may provide variable control for the transfer case output speeds. This may allow the transfer case first output speed to be adjusted to accommodate the different transmission output speeds of the transmission.

According to a further aspect of the invention, a vehicle is provided comprising a system as described in the preceding paragraphs.

According to yet another aspect of the invention, there is provided a power transmission means arranged to receive an input power of an engine and to transmit power from the engine via a first output power to drive two wheels on a first axle; the input power from the engine being additionally provided as a second output power from the power transmission means to a transmission means via a propeller shaft.

The power transmitting means may comprise: a gear arrangement; and at least one clutch arranged to be positioned, in use, between the engine and the gear arrangement; the gear arrangement and at least one clutch configured to enable the transfer case to provide the first output power at a plurality of different speeds such that when a transmission means is in a first subset of gears, the power transmitting means provides the first output power speed at a first speed, and when a transmission means is in a second, different subset of gears, the power transmitting means provides the first output power speed at a second, different speed.

According to one aspect of the invention, there is provided a system for providing four-wheel drive in a vehicle, the system comprising: a transmission comprising a plurality of gears, the transmission arranged to be coupled to an engine via a propeller shaft and arranged to drive two primary wheels; a transfer case arranged to be coupled to the engine and arranged to drive two secondary wheels; the transfer case comprising a gear assembly and at least one clutch positioned between the engine and the gear assembly; the gear assembly and the at least one clutch configured to enable the transfer case to provide output at a plurality of different speeds such that when the transfer case is in a first subset of gears, the transfer case provides output at a first speed, and when the transmission is in a second, different subset of gears, the transfer case provides output at a second, different speed.

According to one aspect of the invention there is provided a control system for controlling a four-wheel drive vehicle, comprising: means for receiving one or more signals indicative of a current gear of a transmission; means for controlling the output of a transfer case by providing a control signal to the transfer case, the control signal being dependent on the current gear of the transmission.

The control signal may include information indicating the current gear of the transmission.

According to one aspect of the invention, there is provided a control system for controlling a four-wheel drive vehicle as described above, wherein; the means for receiving one or more signals indicative of the current gear of a transmission comprises an electronic processor having an electrical input for receiving the one or more signals indicative of the current gear of a transmission; and an electronic storage device electrically coupled to the electronic processor and having instructions stored therein; the means for controlling the output power speed of a transfer case by providing a control signal to the transfer case comprises the processor being configured to access the storage device and execute the instructions stored therein so that it is operable to control the output power speed of a transfer case by providing a control signal to the transfer case.

According to one aspect of the invention there is provided a system for providing four wheel drive in a vehicle, the system comprising; a transmission means comprising a plurality of gears, the transmission means being arranged to be coupled to an engine via a propeller shaft and arranged to drive two primary wheels; a power transmission means arranged to be coupled to an engine and configured to drive two secondary wheels; the power transmission means comprising a first clutch configured to connect a gear arrangement between the propeller shaft and the secondary wheels and a second clutch configured to disconnect the gear arrangement such that when the transmission means is in a first subset of gears, the gear arrangement is connected such that the power transmission means provides an output power at a first speed, and when the transmission means is in a second, different subset of gears, the gear arrangement is disconnected such that the power transmission means provides an output power at a second, different speed.

According to one aspect of the invention there is provided a system for providing four-wheel drive in a vehicle, the system comprising; a transmission means comprising a plurality of gears, the transmission means arranged to be coupled to an engine via a propeller shaft and arranged to drive two primary wheels; a power transmission means arranged to be coupled to an engine and configured to drive two secondary wheels; the power transmission means arranged to provide an output power at a plurality of different speeds such that when the transmission means is in a first subset of gears, the power transmission means provides an output power at a first speed, and when the transmission means is in a second, different subset of gears, the power transmission means provides an output power at a second, different speed.

According to one aspect of the invention there is provided a system for providing four-wheel drive in a vehicle, the system comprising; a transmission means comprising a plurality of gears, the transmission means being arranged to be coupled to an engine via a propeller shaft and arranged to drive two primary wheels; a power transmission means arranged to be coupled to an electric motor and configured to drive two secondary wheels; the power transmission means comprising a gear arrangement and at least one clutch positioned between the electric motor and the gear arrangement; the gear arrangement and the at least one clutch being configured to enable the power transmission means to provide output power at a plurality of different speeds such that when the transmission means is in a first subset of gears, the power transmission means provides output power at a first speed, and when the transmission means is in a second, different subset of gears, the power transmission means provides output power at a second, different speed.

Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives presented in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular their individual features, may be considered independently of each other or in any combination. This means that all embodiments and/or features of any embodiment may be combined in any way and/or in any combination, provided that these features are not incompatible. The applicant reserves the right to amend any originally filed patent claim or to file any new patent claim accordingly, including the right to modify any originally filed patent claim. to depend on and/or incorporate any feature of any other claim, even though it was not previously claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

• 1ein beispielhaftes Fahrzeug, das erfindungsgemäße Ausführungsformen umfassen kann;
• 2 ein beispielhaftes System;
• 3 einen Teil eines beispielhaften Systems;
• 4 ein beispielhaftes Verteilergetriebe;
• 5 schematisch eine Ganganordnung und eine oder mehrere Kupplungen;
• 6 schematisch eine weitere Ganganordnung und eine oder mehrere Kupplungen; und
• 7 eine Steuervorrichtung.

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

• 1a exemplary vehicle that may include embodiments of the invention;
• 2 an exemplary system;
• 3 a part of an exemplary system;
• 4 an exemplary transfer case;
• 5 schematically a gear arrangement and one or more clutches;
• 6 schematically a further gear arrangement and one or more clutches; and
• 7 a control device.

DETAILED DESCRIPTION

Examples of the present disclosure relate to systems that may be used to control four-wheel drive in a vehicle 1. For example, some examples relate to systems that may be used to control four-wheel drive in a vehicle 1 with a rear transaxle.

1 illustrates an exemplary vehicle 1 that may include a system 3 according to examples of the present disclosure. It is noted that the vehicle 1 is 1 is provided as an example and that examples of the disclosure may be provided in any four-wheel drive vehicle 1.

2 represents an exemplary system 3. The system 3 from 2 may be arranged for use in a rear transaxle vehicle 1 in which the engine 15 is mounted at the front of the vehicle 1 and the transmission 7 is mounted at the rear. It is noted that other systems 3 may be used in other types of vehicle 1.

3 and 4 represent part of the exemplary system 3 2 Corresponding reference symbols are used for corresponding features. 3 represents a transfer case 5 which is coupled to the engine 15. 4 represents the same transfer case 5 with the engine 15 removed.

The exemplary system 3 includes a power transfer means 5 and a transmission means 7. The power transfer means may include a transfer case 5 and the transmission means may include a transmission 7. The system 3 is arranged to be connected to an engine 15 such that the transmission 7 can provide power from the engine 15 to the two primary wheels of the vehicle 1 and the transfer case 5 can provide power from the engine 15 to the two secondary wheels of the vehicle 1. A drive shaft 31 can be provided between the transfer case 5 and the front axle 13. A differential gear 41 can be provided between the wheels.

In the exemplary system 3, the primary wheels are the rear wheels 19 of the vehicle 1. The transmission 7 is mounted on the rear axle 9. The transmission 7 is connected to the rear axle 9 such that the transmission 7 is arranged to drive the two rear wheels 19.

The transmission 7 is coupled to the engine 15 via a propeller shaft 18. The propeller shaft 18 may be provided in a thrust tube 17. The propeller shaft 18 is arranged to couple the engine 15 to the transmission 7 such that power from the engine 15 can be provided to the transmission 7. The propeller shaft 18 may rotate at the same speed as the engine 15. Thus, the input power speed to the transmission 7 may be the same as the output power speed of the engine 15.

In the exemplary system from 2 the engine 15 is mounted on the axle 13 opposite the transmission 7. The engine 15 is mounted on the front axle 13, while the transmission 7 is mounted on the rear axle 9. Since the engine 15 and the transmission 7 are mounted on different axles 9, 13, the propeller shaft 18 extends in the thrust tube 17 along the length of the vehicle 1.

The transmission 7 includes a plurality of gears. The gears allow the output of the transmission 7 to have a different speed than the input power provided by the engine 15. The transmission 7 may have any suitable number of gears. In some examples, the transmission 7 may have five gears. In other examples, the transmission 7 may have more than five gears. For example, the transmission 7 could have six or eight gears, or any other suitable number.

The exemplary system 3 may also include a transfer case 5. The transfer case 5 may provide a power transfer means. The transfer case 5 may be arranged to transfer power from the engine 15 to the front axle 13. This may allow the transfer case 5 to drive the two secondary wheels. In the exemplary system 3 of 2 the secondary wheels are the front wheels 11 (as in 1 shown).

The transfer case 5 is arranged to be coupled to the engine 15. In some examples, the transfer case 5 may be coupled directly to the engine 15 without intervening components. The transfer case 5 may be coupled to the engine 15 such that input power to the transfer case 5 is provided at the same speed as the engine 15.

In the exemplary system from 2 the transfer case 5 is positioned behind the engine 15. The transfer case 5 is positioned between the engine 15 and the transmission 7. The transfer case 5 can be provided near the front axle 13. This can reduce the length of a required drive shaft between the transfer case 5 and the front axle 13.

The transfer case 5 includes a power transmitting means that enables the transfer case 5 to provide an output power at a different speed than the input power. In some examples, the transfer case 5 may include one or more clutches 53, 55 and a gear arrangement 51 that may be arranged to provide an output power at a different speed than the input power.

The one or more clutches 53, 55 and a gear arrangement 51 may be arranged such that the plurality of different output speeds of the transfer case 5 can be correlated with the different output power speeds of the transmission 7 (see, for example, 5 ). The correlation between the speeds of the transfer case 5 with the speeds of the transmission 7 may enable the output power speeds of the transfer case 5 to be similar to or the same as the output power speeds of the transmission 7. For example, when the transmission 7 is in a low gear, the one or more clutches 53, 55 and a gear assembly 51 may be arranged to provide a first output power speed, which may be a low speed, and when the transmission 7 is in a higher gear, the one or more clutches 53, 55 and a gear assembly 51 may be arranged to provide a second output power speed, which may be a higher speed.

The one or more clutches 53, 55 and a gear arrangement 51 may be arranged such that when the transmission 7 is in a first subset of gears, the transfer case 5 provides output at a first speed, and when the transmission 7 is in a second, different subset of gears, the transfer case 5 provides output at a second, different speed. In some examples, when the transmission 7 is in a third, different subset of gears, the transfer case 5 provides output at a third, different speed.

It should be noted that the transfer case 5 could have any number of output power speeds configured to correspond to any number of subsets of gears of the transmission 7. The subsets of gears of the transmission 7 could include one or more gears. In examples where a subset includes more than one gear, the one or more clutches 53, 55 and gear assembly 51 can be arranged to allow the speed of the transfer case to cover a range of speeds provided by the transmission 7. Different subsets can include a different number of gears.

5 and 6 schematically illustrate exemplary gear arrangements 51 and clutches 53, 55, 63 that may be provided in the transfer case 5.

5 schematically illustrates a gear arrangement 51 and one or more clutches 53, 55 that may be provided in a transfer case 5 in some examples of the disclosure. The transfer case 5 may be provided between the engine 15 and the transmission 7, which in 2 to 4 is pictured.

In the example from 5 the transfer case 5 receives an input power 52 from the engine 15. The input power 52 from the engine 15 may be provided at the same speed as that of the engine 15. The input power 52 from the engine 15 may also be provided as an output power 54 to the transmission 7 via the propeller shaft 18. The gear arrangement 51 and the one or more clutches 53, 55 are provided between the input power 52 from the engine 15 and the front axle 13.

The output 56 of the transfer case 5 is provided to the front axle 13 to drive the front wheels 11. The gear assembly 51 and the one or more clutches 53, 55 control the speed of the output speed 56. The gear assembly 51 and the one or more clutches 53, 55 are arranged to correlate the output speed of the transfer case 5 with the output speed of the transmission 7. In some examples, the gear assembly 51 and the one or more clutches 53, 55 may be arranged to enable the output speed of the transfer case 5 to match the output speed of the transmission 7.

The transfer case 5 includes a first clutch 53 and a second clutch 55. In other examples, more than two clutches 53, 55 could be provided. Having more than two clutches 53, 55 could allow more different gear arrangements 51 to be connected to the input power 52 from the engine 15 and allow a greater number of different output speeds to be provided by the transfer case 5.

The first clutch 53 is coupled to a gear assembly 51. The first clutch 53 enables the gear assembly 51 to be connected between the input power from the engine 15 and the output power of the front axle 13.

In the example from 5 the gear assembly 51 includes two planetary gears. The planetary gears include a first planetary stage 57 and a second planetary stage 59. The two-stage gear assembly 51 may allow two different gear ratios to be provided. This allows multiple output power speeds to be provided by the gear assembly 51.

The second clutch 55 is not coupled to the gear assembly 51. The second clutch 55 allows the gear assembly 51 to be disconnected between the input power 52 from the engine 15 and the output power 56 of the front axle 13. The second clutch 55 allows the input power 52 from the engine 15 to be connected to the output power 56 of the front axle 13.

The exemplary transfer case 5 has three speeds provided by different configurations of the gear assembly 51 and the clutches 53, 55. The first speed may be provided when the first clutch 53 is closed and the first planetary stage 57 of the gear assembly 51 is held fixed. The second speed may be provided when the first clutch 53 is closed and the first planetary stage 57 of the gear assembly 51 is engaged with the carrier of the planetary gears. The third speed may be provided by opening the first clutch 53 and closing the second clutch 55. This disconnects the gear assembly 51 from the input power 52 from the engine 15 and allows the output power 56 to the front axle 13 to be connected to the input power 52 from the engine 15. The third speed may enable one-to-one shifting with the input power 52 from the engine 15 and the propeller shaft 18.

The clutch and gear arrangement may be arranged such that the output speeds of the transfer case 5 match the outputs of the transmission 7. When the speeds are adjusted, they could be the same or similar to the speed of the transmission 7. In some examples, the first speed of the transfer case 5 may match the lower gears of the transmission 7. The lower gears could be the first and second gears of the transmission 7. The second speed of the transfer case 5 could match the middle gears of the transmission 7. The middle gears could be the third and fourth gears. The third speed of the transfer case 5 could match the higher gears of the transmission 7. The higher gears of the transmission 7 could be the fifth and/or higher gears.

As an example, the first speed of the transfer case 5 could have a gear ratio of 3.9:1, the second speed could have a gear ratio of 1.9:1, and the third speed could have a ratio of 1:1. It should be noted that other gear ratios could be provided in other examples of the disclosure.

The transfer case 5 may be configured to receive a control signal indicative of the current gear of the transmission 7. In response to receiving the control signal, the transfer case 5 may be arranged to control the clutches 53, 55 and the gear assembly 51 to provide the output power speed corresponding to the current gear of the transmission 7.

In the example from 5 The gearbox 7 has five speeds, the transfer case 5 however, only has three. Since the transmission 7 has more speeds than the transfer case 5, the gear arrangement 51 and the clutches 53, 55 of the transfer case 5 are arranged such that one configuration of the transfer case 5 can overlap more than one speed of the transmission 7. In the example from 5 this may be achieved by having slippable clutches. The slippable clutches may be arranged such that in some gear configurations of the transmission 7 and transfer case 5, the clutches 53, 55 may be arranged to slip at a fixed speed under torque to enable the correct wheel speed to be provided by both the front wheels 11 and the rear wheels 19. The slippable clutches may be arranged to slip in gear configurations in which the ratio of engine speed to wheel speed for the rear wheels 19 does not match the ratio of engine speed to wheel speed for the front wheels 11. Other suitable means may be used in other examples of the disclosure.

If both of the clutches 53, 55 are disengaged, then the input power 52 from the engine 15 is not connected to the transfer case 5. The four-wheel drive is disabled since no power is provided from the transfer case 5 to the front wheels 19.

6 schematically illustrates another gear arrangement 51 and clutch 63 that may be provided in a transfer case 5 in some examples of the disclosure.

The transfer case 5 from 6 includes a gear assembly 51 and a clutch 63 and an electric motor 61. The electric motor 61 may be configured to provide power to the front wheels 11 via the gear assembly 51. The electric motor 61 may provide a secondary motor. The position of the clutch 63 may be controlled by an electro-mechanical or hydraulic actuator. This may control the torque through the gear assembly 51. The power provided by the electric motor 61 and/or the position of the clutch 63 may be arranged such that the output power of the transfer case 5 can be correlated with the output speed of the transmission 7.

The power provided by the electric motor 61 and/or the position of the clutch 63 may be controlled in response to an input control signal. The electric motor 61 may receive a control signal indicative of the current gear of the transmission 7. In response to the control signal, the electric motor 61 may control the power provided by the electric motor 61 and/or the position of the clutch 63.

The clutch 63 may be arranged in an open configuration that allows the electric motor 61 to be disconnected from the front wheels 11. In such arrangements, no output power 56 is provided from the transfer case 5 to the front axle 13.

In examples of the disclosure, the configuration of the gear arrangement 51 and the clutches 53, 55, 63 in the transfer case 5 is dependent on the current gear of the transmission 7. A controller 71 may be provided to enable the arrangement of the transfer case 5 to be controlled to correlate the current gear of the transmission 7 with the output speed of the transfer case 5. The controller 71 may be configured to receive an input indicative of the current gear of the transmission 7 and provide an output control signal to the transfer case 5 to control the output speed of the transfer case 5.

An exemplary control device 71 is shown in 7 and described below. In other examples, the control device 71 could include a hydraulic and/or mechanical system or any other means.

7 illustrates an exemplary controller 71. The controller 71 may be a chip or a chipset. The controller 71 may form part of one or more systems included in the vehicle 1. The controller 71 may be configured to control the four-wheel drive of the vehicle 1.

The incorporation of a controller 71 may be as a controller circuit. The controller 71 may be incorporated as hardware alone, may have certain aspects related to software including firmware alone, or may be a combination of hardware and software (including firmware).

As in 7 As shown, the controller 71 may be implemented using instructions that enable hardware functionality, for example using executable instructions of a computer program 77 in a general purpose processor or in a special purpose processor 73, which may be stored in a computer-readable storage medium (floppy disk, memory, etc.) for execution by such processor 73.

The processor 73 is configured to read and write to the memory 75. The processor 73 may also include an output interface through which data and/or commands are output by the processor 73 and an input interface through which data and/or commands are input to the processor 73.

The memory 75 stores a computer program 73 that includes computer program instructions 79 (computer program code) that, when loaded into the processor 73, controls the operation of the controller 71. The computer program instructions 79 of the computer program 77 provide the logic and routines that enable the controller 71 to control the output power speed of the transfer case 5. The processor 73 is able to load and execute the computer program 77 by reading the memory 75.

The control device 71 thus comprises: at least one processor 73; and at least one memory 75 including computer program code, wherein the at least one memory 75 and the computer program code are configured to cause the control device 71 to at least perform the following with the at least one processor 73: receive one or more signals indicative of a current gear of a transmission 7 and control the output speed of a transfer case 5 by providing a control signal to the transfer case 5, wherein the control signal is dependent on the current gear of the transmission 7.

As in 7 As shown, the computer program 77 may arrive at the controller 71 via any suitable delivery mechanism 81. The delivery mechanism 81 may be, for example, a non-transitory computer-readable storage medium, a computer program product, a storage device, a recording medium such as a Compact Disc Read-Only Memory (CD-ROM) or a Digital Versatile Disc (DVD), an article of manufacture that tangibly embodies the computer program 77. The delivery mechanism may be a signal configured to reliably transmit the computer program 77. The controller 71 may propagate or transmit the computer program 77 as a computer data signal.

Although memory 75 is illustrated as a single component/circuit, it may be implemented as one or more separate components/circuits, some or all of which may be built-in/removable and/or may provide permanent/semi-permanent/dynamic/cache memory.

Although the processor 73 is illustrated as a single component/circuit, it may be implemented as one or more separate components/circuits, some or all of which may be removable. The processor 10 may be a single-core or multi-core processor.

For purposes of this disclosure, it is noted that the control device(s) described herein may each comprise a control unit or a computing device having one or more electronic processors. A vehicle and/or a system thereof may comprise a single control unit or electronic control device, or alternatively, different functions of the control device(s) may be embodied or incorporated in different control units or control devices. A set of instructions could be provided that, when executed, cause the control device(s) or control units(s) to implement the control techniques described herein (including the described method(s). The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions could be provided as software executed by one or more electronic processors. For example, a first control device may be implemented in software running on one or more electronic processors, and one or more other control devices may also be implemented in software running on one or more electronic processors, optionally the same or the same multiple processors as the first control device. It should be understood, however, that other arrangements are also useful and, thus, the present disclosure is not intended to limit any particular arrangement. In any event, the embodiments described above may be embodied in a computer-readable storage medium (e.g., a non-volatile storage medium) comprising any mechanism for storing information in a form readable by a machine or electronic processor/computing device, including, but not limited to: a magnetic storage medium (e.g., a floppy disk); an optical storage medium (e.g., CD-ROM); a magnetic optical storage medium; a read-only memory (ROM); a random access memory (RAM); an erasable storable memory (e.g., EPROM ad EEPROM); a flash memory; or electrical or other types of media. to store such information/instructions.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be noted that modifications to the examples given may be made without departing from the scope of the claimed invention. In the examples described above, a rear transaxle vehicle is provided in which the engine is mounted at the front of the vehicle and the transmission is mounted at the rear. In other examples, the engine could be mounted at the rear of the vehicle and the transmission could be mounted at the front.

Features described in the preceding description may be used in combinations other than those expressly described.

Although functions have been described with reference to certain features, those functions are executable by other functions, whether described or not.

Furthermore, although features have been described with reference to particular embodiments, these features may be present in other embodiments, whether described or not.

While attempting to draw attention in the above specification to those inventive features believed to be of particular importance, it should be noted that the applicant claims protection in respect of each patentable feature or combination of features referred to above and/or shown in the drawings, whether or not particular emphasis has been placed thereon.

Claims (17)

A system (3) for providing four-wheel drive in a vehicle (1), the system (3) comprising: a power transmission means (5) comprising a gear arrangement (51) and at least one clutch (53, 55), the power transmission means (5) being arranged to receive an output from an engine (15) and being arranged to transmit power from the engine (15) via the gear arrangement (51) and the at least one clutch (53, 55) to provide a first output at a first gear ratio to drive two wheels (11) on a first axle (13), the at least one clutch (53, 55) being arranged between the engine (15) and the gear arrangement (51); a transmission means (7) arranged to receive the output of the engine (15) via a propeller shaft (18); wherein the transmission means (7) is arranged to transmit power from the engine (15) to drive two wheels (19) on a second axle (9); wherein the at least one clutch (53, 55) is configured to slip when the ratio of engine speed to wheel speed of at least one wheel (19) on the second axle (9) does not match the ratio of engine speed to wheel speed of at least one wheel (11) on the first axle (13). System (3) according to one of the preceding claims, wherein the transmission means (7) is a gearbox (7) and the power transmission means (5) is a transfer case (5). System (3) according to Claim 1 or 2 , wherein the gear arrangement (51) and the at least one clutch (53, 55) are configured to enable the power transmission means (5) to provide the first output power at a plurality of different first gear speeds for driving the two wheels (11) on the first axle (13); and wherein the transmission means (7) comprises a plurality of gears, the gears arranged to provide transmission drive at a plurality of different second gear speeds for driving the two wheels (19) on the second axle (9). System (3) according to Claim 3 , wherein the gear arrangement (51) and the at least one clutch (53, 55) are arranged such that the plurality of different first transmission speeds of the power transmission means (5) can be correlated with the plurality of different second transmission speeds of the transmission means (7). System (3) according to Claim 4 , wherein the interrelationship of the plurality of first gear speeds of the power transmission means (5) and the plurality of second gear speeds of the transmission means (7) enables the first output power of the power transmission means (5) to match the transmission output power of the transmission means (7). System (3) according to one of the Claims 3 until 5 wherein, when the transmission means (7) is in a first subset of gears, the power transmission means (5) provides the first output power at one of the plurality of first gear ratios and, when the transmission means (7) is in a second, different subset of gears, the power transmission means (5) provides the first output power at a second, different first gear ratio of the plurality of first gear ratios. System (3) according to Claim 6 wherein the gear arrangement (51) and the at least one clutch (53, 55) are configured such that when the transmission means (7) is in a third different subset of gears, the power transmission means (5) provides the first output power at a third different first gear speed of the plurality of first gear speeds. System (3) according to one of the Claims 1 until 7 wherein the power transmission means (5) comprises a plurality of clutches (53, 55) configured to enable different gear arrangements (51) to be connected. System (3) according to one of the Claims 1 until 8th wherein one or more of the at least one clutch (53, 55) disconnects the gear assembly (51) from the input of the engine (15) and the two wheels (11) on the first axle (13) and couples the two wheels (11) on the first axle (13) to the input from the engine (15). System (3) according to Claim 9 wherein the one or more of the at least one clutch (53, 55) disengaging the gear arrangement (51) enables one-to-one switching between the input from the engine (15) and the first output of the power transmission means (5). System (3) according to one of the Claims 1 until 10 , wherein the gears in the gear arrangement (51) comprise planetary gears. A system (3) according to any preceding claim, wherein the input to the power transmission means (5) rotates at engine output power speed. A system (3) according to any preceding claim, comprising a control device (71) configured to determine a current gear of the transmission means (7) and to provide a control signal to the power transmission means (5) indicative of the current gear of the transmission means (7). System (3) according to one of the preceding claims, wherein the vehicle (1) is a rear transaxle vehicle (1). A system (3) according to any preceding claim, wherein the power transmission means (5) is arranged to be coupled to a rear side of the motor (15). System (3) according to one of the preceding claims, wherein the power transmission means (5) is coupled to an electric motor which provides power to the power transmission means (5). Vehicle (1) comprising a system (3) according to one of the preceding claims.

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