Bridge driving system and vehicle

Abstract

The utility model provides an electric bridge driving system and a vehicle, and belongs to the technical field of automobile electric bridge driving systems.The electric bridge driving system comprises an input shaft, an intermediate shaft, a first transmission assembly, a second transmission assembly and an output assembly; the input shaft is connected with a power source, and a first gear and a second gear are arranged on the input shaft; the first transmission assembly, the second transmission assembly and the output assembly are all integrated on the intermediate shaft and are coaxially arranged with the intermediate shaft, the first transmission assembly is connected between the first gear and the intermediate shaft, and the second transmission assembly is connected between the second gear and the intermediate shaft. According to the bridge driving system, the first transmission assembly, the second transmission assembly and the output assembly are integrated on the intermediate shaft, an integrated shaft structure is formed, the number of parts is reduced, meanwhile, the occupied space in the axial direction of the bridge is greatly reduced, the space layout is optimized, and the space utilization rate is increased.

Description

Technical Field

[0001] The present application relates to the field of electric bridge drive technology, and in particular to an electric bridge drive system and a vehicle. Background Art

[0002] With the rapid development of new energy, pure electric mechanisms are becoming the first choice for people's travel, and the transmission industry is gradually shifting towards pure electric directions.

[0003] Currently, most car companies use either a single-speed mechanism for power drive or a hybrid gear shifting method for drive during pure electric driving. For the electric bridge drive system with multi-speed control, the internal transmission component layout is complex and occupies a relatively large space, resulting in a relatively large size of the entire electric bridge structure, which does not truly realize the ideal of electric drive. Utility Model Content

[0004] In view of this, the present application aims to propose an electric bridge drive system to solve the problems of complex layout and large space size of the electric bridge drive system in the related art.

[0005] To achieve the above purpose, the technical solution of this application is implemented as follows:

[0006] An electric bridge driving system, comprising:

[0007] An input shaft, an intermediate shaft, a first transmission assembly, a second transmission assembly, and an output assembly;

[0008] The input shaft is connected to a power source, and a first gear and a second gear are arranged on the input shaft;

[0009] The first transmission assembly, the second transmission assembly and the output assembly are all integrated on the intermediate shaft and are coaxially arranged with the intermediate shaft. The first transmission assembly is connected between the first gear and the intermediate shaft, and the second transmission assembly is connected between the second gear and the intermediate shaft.

[0010] Further, the first transmission assembly includes a first clutch and a third gear;

[0011] The third gear is sleeved on the outer circumference of the intermediate shaft and meshes with the first gear;

[0012] The first clutch is disposed between the third gear and the intermediate shaft. The first clutch comprises an outer hub and an inner hub. The outer hub is fixedly connected to the third gear, and the inner hub is fixedly connected to the intermediate shaft.

[0013] Furthermore, the second transmission assembly includes a second clutch; the second clutch includes an outer shell, an inner shell and a friction plate group arranged between the outer shell and the inner shell, the outer wall of the outer shell is provided with a gear structure, the gear structure is meshed with the second gear, and the inner shell is fixedly connected to the intermediate shaft.

[0014] Furthermore, the output assembly includes a planetary gear set, which includes a sun gear, planetary gears, a planet carrier and a ring gear; the sun gear is fixedly connected to the intermediate shaft, the ring gear is coaxially arranged on the outer periphery of the sun gear, the planetary gear is mounted on the planet carrier, the planetary gear is located between the ring gear and the sun gear, the planetary gear is meshed with the sun gear, and the planetary gear is meshed with the inner ring of the ring gear.

[0015] Further, the bridge drive system includes a first state and a second state;

[0016] In the first state, the first clutch connects the third gear and the intermediate shaft, and the second clutch disconnects the second gear and the intermediate shaft, so that the planetary gear set outputs a first speed;

[0017] In the second state, the first clutch disconnects the third gear from the intermediate shaft, and the second clutch connects the second gear to the intermediate shaft, so that the planetary gear set outputs a second speed.

[0018] Furthermore, the inner housing, the sun gear and the intermediate shaft are an integrally formed structure.

[0019] Furthermore, the inner hub is connected to the intermediate shaft via a spline, and the outer hub is connected to the third gear via a spline.

[0020] Furthermore, the first gear, the second gear and the input shaft are an integrally formed structure.

[0021] Furthermore, the electric bridge drive system also includes a transmission, and the ring gear is fixedly connected to a housing of the transmission.

[0022] Furthermore, the power source includes a drive motor.

[0023] Compared with the prior art, the electric bridge drive system described in this application has the following advantages:

[0024] (1) The electric bridge drive system described in the present application includes an input shaft, an intermediate shaft, a first transmission assembly, a second transmission assembly and an output assembly; the input shaft is connected to a power source, and a first gear and a second gear are provided on the input shaft; the first transmission assembly, the second transmission assembly and the output assembly are all integrated on the intermediate shaft and are coaxially arranged with the intermediate shaft, the first transmission assembly is connected between the first gear and the intermediate shaft, and the second transmission assembly is connected between the second gear and the intermediate shaft; the present application forms an integrated shaft structure by integrating the first transmission assembly, the second transmission assembly and the output assembly on the intermediate shaft, thereby reducing the number of components and greatly reducing the space occupied by the electric bridge in the axial direction, optimizing the space layout and improving the space utilization.

[0025] (2) In the electric bridge drive system described in the present application, the first transmission component includes a first clutch and a third gear, and the second transmission component includes a second clutch. By changing the working states of the first clutch and the second clutch, the transmission path can be changed, the transmission ratio can be changed, and switching between two different gears can be achieved. With the cooperation of the first clutch and the second clutch, the gear shifting process can be smooth and there is no power interruption, which is beneficial to reducing the energy loss of the motor.

[0026] Another object of the present application is to provide a vehicle, comprising the electric axle drive system as described above.

[0027] The advantages of the vehicle and the above-mentioned electric bridge drive system over the prior art are the same, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0029] Figure 1 This is a schematic diagram of the structure of the electric bridge drive system described in an embodiment of the present application;

[0030] Figure 2 This is a simplified structural diagram of the electric bridge drive system described in an embodiment of the present application.

[0031] Description of reference numerals:

[0032] 1. Input shaft; 2. Intermediate shaft; 3. First clutch; 31. Outer hub; 32. Inner hub; 4. Second clutch; 41. Outer shell; 42. Inner shell; 43. Friction plate group; 5. First gear; 6. Second gear; 7. Third gear; 81. Sun gear; 82. Ring gear; 83. Planet carrier; 9. Motor. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0034] In addition, the directions or positional relationships indicated by "upper", "lower", "left", "right", "front", "back", etc. mentioned in the embodiments of the present application are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application. In addition, relational terms such as "first" and "second" are merely used to distinguish one entity from another, and do not necessarily require or imply any such actual relationship or order between these entities, nor can they be understood as indicating or implying relative importance.

[0035] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0036] In the related art, the electric bridge drive system with multi-gear control mode has a complex layout of internal transmission components and occupies a large space, resulting in a large size of the entire electric bridge structure. In addition, the current multi-gear electric bridge drive usually uses a synchronizer to perform the gear shift operation, and there is a problem of power interruption during the gear shift process, resulting in high energy loss and high cost.

[0037] In view of this, an embodiment of the present application provides an electric bridge driving system.

[0038] See also Figure 1 and Figure 2 , an electric bridge drive system, comprising an input shaft 1, an intermediate shaft 2, a first transmission assembly, a second transmission assembly and an output assembly; the input shaft 1 is connected to a power source, and a first gear 5 and a second gear 6 are provided on the input shaft 1; the first transmission assembly, the second transmission assembly and the output assembly are all integrated on the intermediate shaft 2 and are coaxially arranged with the intermediate shaft 2, the first transmission assembly is connected between the first gear 5 and the intermediate shaft 2, and the second transmission assembly is connected between the second gear 6 and the intermediate shaft 2.

[0039] Specifically, the first gear 5 and the second gear 6 are fixed on the input shaft 1. When the power output by the power source is transmitted to the input shaft 1, the first gear 5 and the second gear 6 can rotate synchronously with the input shaft 1. The first transmission assembly is movably connected between the first gear 5 and the intermediate shaft 2, and can connect or disconnect the first gear 5 and the intermediate shaft 2. When the first transmission assembly connects the first gear 5 and the intermediate shaft 2, power can be transmitted from the first gear 5 to the intermediate shaft 2. When the first transmission assembly disconnects the first gear 5 and the intermediate shaft 2, power cannot be transmitted from the first gear 5 to the intermediate shaft 2.

[0040] The second transmission component is movably connected between the second gear 6 and the intermediate shaft 2, and can connect or disconnect the second gear 6 and the intermediate shaft 2. When the second transmission component connects the second gear 6 and the intermediate shaft 2, power can be transmitted from the second gear 6 to the intermediate shaft 2. When the second transmission component disconnects the second gear 6 from the intermediate shaft 2, power cannot be transmitted from the second gear 6 to the intermediate shaft 2.

[0041] Under the setting of the first transmission component and the second transmission component, two transmission paths with different transmission ratios are formed, wherein the first path is: power is transmitted along the input shaft 1, the first gear 5, and the first transmission component to the intermediate shaft 2, and then output from the output component; the second path is: power is transmitted along the input shaft 1, the second gear 6, the second transmission component to the intermediate shaft 2, and then output from the output component.

[0042] For the two-gear controlled electric bridge drive system, the two different transmission paths correspond to two different gears. In the first gear, the first transmission component connects the first gear 5 and the intermediate shaft 2, and the second transmission component disconnects the second gear 6 and the intermediate shaft 2, so that the power is transmitted along the first path, and the system outputs the first speed; in the second gear, the first transmission component disconnects the first gear 5 and the intermediate shaft 2, and the second transmission component connects the second gear 6 and the intermediate shaft 2, so that the power is transmitted along the second path, and the system outputs the second speed. Therefore, by changing the working state of the first transmission component and the second transmission component, the switching of two different gears can be achieved.

[0043] In this embodiment, the first transmission assembly, the second transmission assembly and the output assembly are integrated on the intermediate shaft 2, and the axes of the first transmission assembly, the second transmission assembly and the output assembly are colinear with the axis of the intermediate shaft 2, forming an integrated shaft structure, which greatly reduces the axial space occupied by the electric bridge drive system, optimizes the spatial layout, and improves space utilization.

[0044] Furthermore, the first transmission assembly includes a first clutch 3 and a third gear 7; the third gear 7 is sleeved on the outer periphery of the intermediate shaft 2 and meshes with the first gear 5; the first clutch 3 is arranged between the third gear 7 and the intermediate shaft 2, and the first clutch 3 includes an outer hub 31 and an inner hub 32, the outer hub 31 is fixedly connected to the third gear 7, and the inner hub 32 is fixedly connected to the intermediate shaft 2.

[0045] For details, see Figure 1The first transmission assembly includes a first clutch 3 and a third gear 7, wherein the third gear 7 can be set as a hollow annular structure, sleeved on the outer periphery of the intermediate shaft 2, and the third gear 7 always keeps meshing with the first gear 5; the first clutch 3 is arranged in a nested manner, arranged between the third gear 7 and the intermediate shaft 2, and includes an outer hub 31 and an inner hub 32, wherein the outer hub 31 and the third gear 7 are fixed together so as not to rotate relative to each other, and the inner hub 32 and the intermediate shaft 2 are fixed together so as not to rotate relative to each other. The outer hub 31 and the inner hub 32 are movably connected, and when the first clutch 3 is in a coupled state, the outer hub 31 and the inner hub 32 are connected as a whole, and the two can rotate synchronously; when the first clutch 3 is in a disengaged state, the outer hub 31 and the inner hub 32 are separated.

[0046] Furthermore, the inner hub 32 and the intermediate shaft 2 may be connected via a spline to ensure that the inner hub 32 and the intermediate shaft 2 cannot rotate relative to each other, and the outer hub 31 and the third gear 7 may be connected via a spline to ensure that the outer hub 31 and the third gear 7 cannot rotate relative to each other.

[0047] Furthermore, the first clutch 3 may be a one-way clutch for one-way power transmission. In other embodiments, the first clutch 3 may be a multi-mode one-way clutch or a friction plate clutch or other suitable clutch types.

[0048] Furthermore, the second transmission assembly includes a second clutch 4; the second clutch 4 includes an outer shell 41, an inner shell 42 and a friction plate group 43 arranged between the outer shell 41 and the inner shell 42, the outer wall of the outer shell 41 is provided with a gear structure, the gear structure is meshed with the second gear 6, and the inner shell 42 is fixedly connected to the intermediate shaft 2.

[0049] See also Figure 1The second transmission assembly includes a second clutch 4, which is also arranged on the outer periphery of the intermediate shaft 2 in a nested manner and is located between the second gear 6 and the intermediate shaft 2. In this embodiment, the second clutch 4 is a friction plate clutch, including an outer shell 41, an inner shell 42 and a friction plate group 43, wherein the outer wall of the outer shell 41 is provided with a gear structure, which is always in mesh with the second gear 6; the inner shell 42 is located inside the outer shell 41 and is fixed to the intermediate shaft 2 in a non-rotatable manner; the friction plate group 43 is nested between the outer shell 41 and the inner shell 42, and can connect or separate the outer shell 41 and the inner shell 42. Specifically, the friction plate group 43 includes a plurality of staggered partition plates and friction plates. The partition plates are connected to the inner wall of the outer shell 41 by splines and can slide axially relative to the outer shell 41. The friction plates are connected to the outer wall of the inner shell 42 by splines and can slide axially relative to the inner shell 42. When the plurality of partition plates and the plurality of friction plates are pressed together, the outer shell 41 and the inner shell 42 are connected as one, and the two can rotate synchronously. At this time, the second clutch 4 is in a coupled state; when the plurality of partition plates and the plurality of friction plates are separated, the outer shell 41 and the inner shell 42 are separated. At this time, the second clutch 4 is in a separated state.

[0050] The second clutch 4 is a friction plate clutch, which utilizes the sliding friction of the friction plate clutch to achieve a smooth gear shifting process without power interruption, thereby reducing the energy consumption of the motor 9.

[0051] Furthermore, the output assembly includes a planetary gear set, which includes a sun gear 81, planetary wheels, a planet carrier 83 and a ring gear 82; the sun gear 81 is fixedly connected to the intermediate shaft 2, the ring gear 82 is coaxially arranged on the outer periphery of the sun gear 81, the planetary wheels are mounted on the planet carrier 83, the planetary wheels are located between the ring gear 82 and the sun gear 81, the planetary wheels are meshed with the sun gear 81, and the planetary wheels are meshed with the inner ring of the ring gear 82.

[0052] Specifically, the sun gear 81 is fixed on the intermediate shaft 2. When the power output by the power source is transmitted to the intermediate shaft 2, the sun gear 81 can rotate along with the intermediate shaft 2. The ring gear 82 is arranged on the outer periphery of the sun gear 81, and the inner ring of the ring gear 82 has inner teeth; the planet carrier 83 is a supporting mechanism for the planetary gear, which is used to install the planetary gear between the sun gear 81 and the ring gear 82; the planetary gear is meshed with the sun gear 81 and the inner ring of the ring gear 82. When the sun gear 81 rotates, the planetary gear rotates around its own axis and revolves around the axis of the sun gear 81. In this way, the power transmitted to the intermediate shaft 2 can be transmitted to the planetary gear along the sun gear 81, and finally output from the planet carrier 83 or the ring gear 82.

[0053] Optionally, the electric bridge drive system further includes a transmission, and the ring gear 82 is fixedly connected to a housing of the transmission.

[0054] See also Figure 2 In the embodiment of the present application, the ring gear 82 is fixed to the housing of the transmission to realize the external fixation of the planetary gear set. Since the ring gear 82 is fixed, the power transmitted to the intermediate shaft 2 is transmitted to the planetary gear along the sun gear 81 and then output from the planet carrier 83.

[0055] It can be understood that the output position of the planetary gear set can be flexibly adjusted according to the actual requirements of the transmission ratio in the system. In this embodiment, the power is ultimately output from the planet carrier 83. In other embodiments, the planet carrier 83 can also be fixed so that the power is ultimately output from the ring gear 82.

[0056] Furthermore, the electric bridge drive system includes a first state and a second state; in the first state, the first clutch 3 connects the third gear 7 and the intermediate shaft 2, and the second clutch 4 disconnects the second gear 6 from the intermediate shaft 2, so that the planetary gear set outputs a first speed; in the second state, the first clutch 3 disconnects the third gear 7 and the intermediate shaft 2, and the second clutch 4 connects the second gear 6 and the intermediate shaft 2, so that the planetary gear set outputs a second speed.

[0057] Specifically, the first state corresponds to the first gear of the electric bridge drive system. In the first state, the first clutch 3 is in a coupled state, the inner hub 32 is connected to the outer hub 31 as a whole, so that the third gear 7 is connected to the intermediate shaft 2. At the same time, the second clutch 4 is in a disengaged state, the inner shell 42 is separated from the outer shell 41, so that the second gear 6 is disconnected from the intermediate shaft 2. The power output by the power source is transmitted to the input shaft 1, the input shaft 1 rotates, driving the first gear 5 to rotate synchronously, the first gear 5 rotates to drive the third gear 7 to rotate, the third gear 7 drives the outer hub 31 to rotate synchronously, the outer hub 31 drives the inner hub 32 to rotate synchronously, and the inner hub 32 drives the intermediate shaft 2 to rotate synchronously. Therefore, the power is transmitted to the intermediate shaft 2 along the first path, and then output through the planetary gear set, and the output speed of the planetary gear set is the first speed.

[0058] The second state corresponds to the second gear of the electric bridge drive system. In the second state, the first clutch 3 is in a disengaged state, the inner hub 32 is separated from the outer hub 31, so that the third gear 7 is disconnected from the intermediate shaft 2. At the same time, the second clutch 4 is in a coupled state, the inner shell 42 is connected to the outer shell 41, so that the second gear 6 is connected to the intermediate shaft 2. The power output by the power source is transmitted to the input shaft 1, the input shaft 1 rotates, driving the second gear 6 to rotate synchronously, the second gear 6 rotates to drive the outer shell 41 to rotate, the outer shell 41 drives the inner shell 42 to rotate synchronously, and the inner shell 42 drives the intermediate shaft 2 to rotate synchronously, thereby, the power is transmitted to the intermediate shaft 2 along the second path, and then output through the planetary gear set, and the output speed of the planetary gear set is the second speed.

[0059] Furthermore, the inner housing 42 , the sun gear 81 and the intermediate shaft 2 are an integrally formed structure.

[0060] like Figure 1 As shown, the inner housing 42 of the second clutch 4, the sun gear 81 of the planetary gear set and the intermediate shaft 2 can be processed into a whole through an integrated molding process, which is beneficial to reducing the development of parts and components, reducing development costs, and simplifying the structure and assembly process.

[0061] Furthermore, the first gear 5 , the second gear 6 and the input shaft 1 are an integrally formed structure.

[0062] The first gear 5, the second gear 6 and the input shaft 1 can also be processed into a whole through an integrated molding process, which is beneficial to reducing the number of parts and improving space utilization.

[0063] Furthermore, the power source includes a drive motor 9 .

[0064] The electric bridge drive system provided in the embodiment of the present application has two different gears, and the working processes corresponding to the two gears are as follows:

[0065] In the first gear, the first clutch 3 connects the third gear 7 to the intermediate shaft 2, and the second clutch 4 disconnects the second gear 6 from the intermediate shaft 2. The power is transmitted along the first path, specifically: input from the input shaft 1, sequentially through the first gear 5, the third gear 7, the outer hub 31 of the first clutch 3, the inner hub 32 of the first clutch 3 to the intermediate shaft 2, and then through the sun gear 81 and the planetary gear to the planet carrier 83, and finally output from the planet carrier 83, and the output speed is the first speed;

[0066] In the second gear, the first clutch 3 disconnects the third gear 7 from the intermediate shaft 2, and the second clutch 4 connects the second gear 6 to the intermediate shaft 2. The power is transmitted along the second path, specifically: input from the input shaft 1, and sequentially transmitted to the intermediate shaft 2 through the second gear 6, the outer shell 41 of the second clutch 4, and the inner shell 42 of the second clutch 4, and then transmitted to the planetary carrier 83 through the sun gear 81 and the planetary gears, and finally output from the planetary carrier 83, and the output speed is the second speed.

[0067] The electric bridge drive system provided in the embodiment of the present application can achieve switching between two different gears by setting the first clutch 3 and the second clutch 4, and changing the transmission path by changing the working state of the first clutch 3 and the second clutch 4. Through the cooperation of the first clutch 3 and the second clutch 4, the gear shifting process is smooth and can avoid the power interruption problem caused by using the synchronizer gear shifting, which is beneficial to reducing the energy loss of the motor 9; at the same time, the first clutch 3, the second clutch 4 and the planetary gear set are integrated on the intermediate shaft 2 to form an integrated shaft structure, so that the first clutch 3 and the second clutch 4 are nested between the input shaft 1 and the intermediate shaft 2, which greatly reduces the axial space occupied by the electric bridge system and improves the space utilization rate.

[0068] An embodiment of the present application also provides a vehicle, comprising the electric axle drive system as described above.

[0069] The advantages of the vehicle and the above-mentioned electric bridge drive system over the prior art are the same, which will not be repeated here.

[0070] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A bridge drive system, characterized in that: include: An input shaft, an intermediate shaft, a first transmission assembly, a second transmission assembly, and an output assembly; The input shaft is connected to a power source, and a first gear and a second gear are arranged on the input shaft; The first transmission assembly, the second transmission assembly and the output assembly are all integrated on the intermediate shaft and are coaxially arranged with the intermediate shaft. The first transmission assembly is connected between the first gear and the intermediate shaft, and the second transmission assembly is connected between the second gear and the intermediate shaft.

2. The electric bridge drive system according to claim 1, characterized in that: The first transmission assembly includes a first clutch and a third gear; The third gear is sleeved on the outer circumference of the intermediate shaft and meshes with the first gear; The first clutch is arranged between the third gear and the intermediate shaft. The first clutch comprises an outer hub and an inner hub. The outer hub is fixedly connected to the third gear, and the inner hub is fixedly connected to the intermediate shaft.

3. The electric bridge drive system according to claim 2, characterized in that: The second transmission assembly includes a second clutch; The second clutch comprises an outer shell, an inner shell and a friction plate group arranged between the outer shell and the inner shell. The outer wall of the outer shell is provided with a gear structure, which is meshed with the second gear. The inner shell is fixedly connected to the intermediate shaft.

4. The electric bridge drive system according to claim 3, characterized in that: The output assembly includes a planetary gear set, and the planetary gear set includes a sun gear, planet gears, a planet carrier and a ring gear; The sun gear is fixedly connected to the intermediate shaft; The ring gear is coaxially arranged on the outer periphery of the sun gear; The planetary gear is mounted on the planet carrier, the planetary gear is located between the ring gear and the sun gear, the planetary gear is meshed with the sun gear, and the planetary gear is meshed with the inner ring of the ring gear.

5. The electric bridge drive system according to claim 4, characterized in that: The electric bridge drive system includes a first state and a second state; In the first state, the first clutch connects the third gear and the intermediate shaft, and the second clutch disconnects the second gear and the intermediate shaft, so that the planetary gear set outputs a first speed; In the second state, the first clutch disconnects the third gear from the intermediate shaft, and the second clutch connects the second gear to the intermediate shaft, so that the planetary gear set outputs a second speed.

6. The electric bridge drive system according to claim 4, characterized in that: The inner housing, the sun gear and the intermediate shaft are an integrally formed structure.

7. The electric bridge driving system according to claim 2, characterized in that: The inner hub is connected to the intermediate shaft via a spline, and the outer hub is connected to the third gear via a spline.

8. The electric bridge driving system according to claim 1, characterized in that: The first gear, the second gear and the input shaft are an integrally formed structure.

9. The electric bridge driving system according to claim 1, characterized in that: The power source includes a drive motor.

10. A vehicle, characterized in that: It comprises the electric bridge drive system as claimed in any one of claims 1 to 9.

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