METHOD FOR ASSEMBLING A VEHICLE TRANSMISSION

Abstract

Method for assembling a vehicle transmission (110) in a transmission housing, comprising: Insertion of a piston assembly (300); Placing a friction element arrangement on a transmission shaft (301); Insertion of a retaining ring (315); Widening of the retaining ring (315); Placing the retaining ring (315) near a mounting groove (390) formed in the transmission shaft (301); and Securing the friction element arrangement by means of the retaining ring (315) by enabling the retaining ring (315) to contract and enter the mounting groove (390); wherein the retaining ring (315) defines a first retaining ring (315) and the method further comprises the following: Inserting a second retaining ring (505); Compressing the second retaining ring (505); Placing the second retaining ring (505) near a pressure plate (309) of the friction element assembly; and Securing the first retaining ring (315) by the second retaining ring (505), by allowing the second retaining ring (505) to expand so that the second retaining ring (505) touches the pressure plate (309), Inserting a retaining ring holder (500) or a third retaining ring (600) before inserting the second retaining ring (505); and Placing the retaining ring holder (500) or the third retaining ring (600) in contact with the first retaining ring (315).

Description

[0001] The present invention relates to a transmission for a motor vehicle and in particular to a transmission designed to prevent a retaining ring securing a friction element arrangement of the transmission from leaving a groove provided for the retaining ring.

[0002] DE 10 2006 060 738 A1 discloses a dual-clutch device. DE 10 2007 027 121 A1 discloses a dual clutch. US 6 193 042 B1 discloses a retaining ring structure in a rotary mechanism and a method for assembling it. US 4 732 253 A discloses a power transmission. DE 10 2005 033 675 A1 discloses a contact piston for a powershift transmission and a method for forming a transmission. A typical transmission for a motor vehicle has several friction element assemblies, for example, clutches or brakes, each friction element assembly containing several plates and friction elements. To actuate a friction element during operation of the vehicle, a piston assembly contacts the plates and friction elements and then presses them together. For this compression to occur, the movement of the plates and friction elements must be restricted in some way.Generally, a retaining ring is provided for this purpose, although sometimes other parts of the gearbox are used if the structure of the gearbox allows it.

[0003] During gearbox assembly, the friction element assembly is installed, followed by the retaining ring, which is a type of circlip that is compressed upon installation. Sufficient space must be available near the friction element assembly to allow the retaining ring to be compressed. After installation, the retaining ring can expand back to its normal size. As the friction element assembly associated with the retaining ring rotates, a centrifugal force acts on the retaining ring, which can cause it to expand if there is sufficient space. Generally, this expansion is blocked by another part of the gearbox, such as the gearbox shaft, and the centrifugal force acts to hold the retaining ring in place.

[0004] If, in contrast, the retaining ring is of the type that expands during installation before it can contract back to its normal size, then the centrifugal force caused by the rotation of a corresponding friction element assembly will cause the retaining ring to expand, and this expansion will not be sufficiently blocked. This is because space must be provided for the retaining ring to expand during assembly, and this space also allows the retaining ring to expand as the friction element rotates. Therefore, this type of retaining ring is typically not used for such applications because the expanded retaining ring can move out of its installed position during operation. If this happens, the friction element assembly associated with this retaining ring cannot be actuated by its piston assembly.However, as gear designs become increasingly complex, it is not always possible to arrange friction element configurations in such a way as to avoid the use of such retaining rings. Therefore, there is a need in the field for a gear design that allows the installation of a retaining ring that expands during assembly and prevents movement after installation.

[0005] An improvement over the prior art is achieved by the features of the independent claims. Preferred embodiments are specified in the further claims. The present invention relates to a method for assembling a vehicle transmission. The transmission comprises a transmission shaft, a friction element assembly mounted on the transmission shaft, a piston assembly for actuating the friction element assembly, a retaining ring for holding the friction element assembly, and an assembly groove formed in the transmission shaft. The retaining ring is inserted into the assembly groove by expanding it and then allowing it to contract again and enter the assembly groove. The assembly groove is arranged such that the retaining ring could be dislodged from the assembly groove if it expands due to a centrifugal force.Accordingly, various arrangements are provided to prevent the retaining ring from leaving the mounting groove after installation.

[0006] In a preferred embodiment, the transmission also includes a transmission element with an assembly groove and an operating groove, and the piston assembly has a corresponding projection. When the piston assembly is in an assembly position, the projection is located in the assembly groove, and the friction element assembly does not cover the assembly groove. When the piston assembly is moved into an operating position by rotation, the projection is located in the operating groove, and a pressure plate of the friction element assembly covers the assembly groove to prevent the retaining ring from leaving the assembly groove due to centrifugal force.

[0007] In another preferred embodiment, the transmission does not include a transmission element with an assembly groove and a service groove. Instead, after the first retaining ring is inserted, a retaining ring holder and a second retaining ring are installed. During assembly, the second retaining ring is compressed and then expands to contact a pressure plate of the friction element assembly. The retaining ring holder is positioned so that it contacts both the first and the second retaining rings. Thus, the second retaining ring and the retaining ring holder prevent the first retaining ring from leaving the assembly groove due to a centrifugal force. Alternatively, a third retaining ring can be used instead of the retaining ring holder.

[0008] Additional tasks, features and advantages of the present invention will become clearer from the following detailed description of preferred embodiments in conjunction with the drawings, in which the same reference numbers in the different views refer to corresponding parts. Fig. Figure 1 is a schematic view of a motor vehicle; Fig. 2A is a partial cross-section of a motor vehicle transmission; Fig. 2B is a schematic view of the gearbox; Fig. 2C is a table with a friction element arrangement actuation schedule for the gearbox; Fig. 3A is a partial cross-section in which a friction element arrangement and a piston arrangement are shown in an operating position according to a first embodiment of the present invention; Fig. 3B is a partial cross-section in which the friction element arrangement and the piston arrangement are shown in an assembly position according to the first embodiment; Fig. Figure 4 is a perspective view showing the friction element arrangement and the piston arrangement in the operating position according to the first embodiment; Fig. 5 is a partial cross-section in which the friction element arrangement and the piston arrangement are shown according to a second embodiment of the present invention; and Fig. Figure 6 is a partial cross-section in which the friction element arrangement and the piston arrangement are shown according to a third embodiment of the present invention.

[0009] Detailed embodiments of the present invention are disclosed here. It is understood, however, that the disclosed embodiments are merely examples of the invention, which can be implemented in various and alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or minimized to show details of certain components. The specific structural and functional details disclosed here should therefore not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art how the present invention can be used in various ways.

[0010] First, reference is made to Fig. Figure 1, in which a motor vehicle 100 according to the present invention is depicted. The vehicle 100 has a power source 105, for example, an internal combustion engine or an electric motor, which is connected to a transmission 110. Power is transmitted from the power source 105 to the transmission 110 and then to a drive shaft 115, which transmits the power through a differential assembly 125 and half-shafts 130, 131 to the rear wheels 120, 121. In such a configuration, the vehicle 100 is a rear-wheel drive vehicle. However, additional configurations are usable in connection with the present invention. For example, in other embodiments, the vehicle 100 can be a front-wheel drive, four-wheel drive, or all-wheel drive vehicle. In the four-wheel drive and all-wheel drive embodiments, the vehicle 100 would also include a transfer case, a second drive shaft, a second differential assembly, and two further half-shafts (not shown).Furthermore, the power source 105 does not have to be located in a front part of the vehicle 100, but can instead be located elsewhere, for example in embodiments with the power unit in the rear or in the middle.

[0011] Now, reference is made to the Fig. 2A and Fig. Figure 2B, in which the transmission 110 is shown in more detail. In this embodiment, the transmission 110 is a ten-speed transmission (i.e., it has ten different forward gear ratios), and the present invention is not limited to use with such a transmission. The transmission 110 comprises an input 200, an output 205, a freewheel clutch 210, a brake A, a brake B, a clutch C, a clutch D, a clutch E, a clutch F, four gear sets, and a piston assembly each for brakes A and B and clutches C, D, E, and F. The four gear sets each comprise a sun gear, a ring gear, and at least one planet gear, which together form a planetary gear set. In particular, Figure 2B shows Fig. 2A comprises a first sun gear 215, a first ring gear 220, and a first planet gear 225, defining a planet gear set 1; a second sun gear 230, a second ring gear 235, and a second planet gear 240, defining a planet gear set 2; a third sun gear 245, a third ring gear 250, and a third planet gear 255, defining a planet gear set 3; and a fourth sun gear 260, a fourth ring gear 265, and a fourth planet gear 270, defining a planet gear set 4. Piston assemblies 275 and 280 are assigned to brakes A and B, respectively, while piston assemblies 285, 290, 295, and 300 are assigned to clutches C, D, E, and F, respectively.

[0012] Each of the brakes A and B and clutches C, D, E and F contains several plates and several friction elements. For example, referring to Fig. 3A and Fig. 3B includes the clutch F, which is coupled to a transmission shaft 301 by means of a splined connection 302 via plates 305, 306, 307, 308 and 309, and friction elements 310, 311, 312 and 313 which are coupled to a clutch drum 303 by means of a further splined connection 304. To actuate the clutch F, a movement of the piston assembly 300 is effected with respect to Fig. 2A is caused to move to the right. As the piston assembly 300 moves to the right, it contacts plate 305, which in turn contacts friction element 310, and so on along the sequence. The rightward movement of plates 305, 306, 307, 308, and 309 and the friction elements 310, 311, 312, and 313 is stopped by a retaining ring 315. At this point, the friction created between plates 305, 306, 307, 308, and 309 and the friction elements 310, 311, 312, and 313 causes all these parts to rotate together. This transmits a rotary motion from the transmission shaft 301 to the clutch drum 303 and vice versa.

[0013] In general, the transmission 110 converts an input torque coming from the power source 105 into an output torque that is delivered to the rear wheels 120, 121 by setting a gear ratio between the input 200 and the output 205 (for example, when upshifting or downshifting). This setting is achieved by actuating or disengaging friction element assemblies (i.e., the freewheel clutch 210, the brakes A and B, and the clutches C, D, E, and F) to change torque ratios by altering gear configurations within the transmission 110. This establishes and releases power flow paths from the power source 105 to the rear wheels 120, 121. This is in conjunction with Fig. 2B, which is a schematic view of gearbox 110, and Fig. 2C, which is a table showing a friction element arrangement actuation schedule, is presented more clearly.

[0014] Now, reference is made to the Fig. 3A and Fig. Figure 3B shows part of the gearbox 110 near clutches C, D, and F. The piston assembly 300 comprises a piston cap 350, a piston spring 355, a compensating piston 360, a piston 365, and a piston retaining ring 370. The piston cap 350 has an opening 375 and a projection 380. During assembly of the gearbox 110, the piston assembly 300 is inserted into the gearbox 110 and moves from the right side into Fig. 3 in the direction of the left side, until the piston assembly 300 contacts a gear element 385. Next, clutch F is inserted into the gearbox 110 and moves from the right side into Fig. 3 towards the left side. As explained above, the retaining ring 315 holds the clutch F in position so that the clutch F is compressed when the piston assembly 300 moves to the right. As in Fig. As can be seen in Figure 3A, there is insufficient space through the pressure plate 309 to insert the retaining ring 315 into an assembly groove 390. To position the retaining ring 315 in the assembly groove 390, the coupling F must be moved further to the left. To achieve this, the piston assembly 300 must also move to the left. However, the piston assembly 300 is not designed to move sufficiently far to the left during assembly, or to compress sufficiently, and at the same time function properly during operation (i.e., to be able to move sufficiently far to the right). To solve this problem, a gear element 385 with an assembly groove 395 and an operating groove 400, best located in Fig. 4 are planned to be shown.

[0015] Accordingly, during assembly, a piston assembly 300 is inserted into the gearbox 110, the projection 380 is aligned with the assembly groove 395 and then inserted into it. The assembly groove 395 is sufficiently deep so that the piston assembly 300 can move far enough to the left (or upwards and to the left with respect to Fig. 4) can move so that the retaining ring 315 can be inserted into the mounting groove 390. In this position, which is described in Fig. As shown in 3B, the piston arrangement 300 cannot move far enough to the right (or downwards to the right with respect to Fig. 4) move to properly actuate the clutch F. To correct this, after the retaining ring 315 is fitted, a tool (not shown) is inserted into the opening 375 of the piston cap 350 and used to move the piston assembly 300 to the right. Once the projection 380 leaves the assembly groove 395, the piston assembly 300 is rotated until the projection 380 is aligned with the operating groove 400. The piston assembly 300 can then move back to the left so that the projection 380, as shown in Fig. 3A and Fig. 4 shows the piston cap 350 moving to the right into the operating groove 400. During operation of the vehicle 100, no forces are exerted that would cause the piston cap 350 to move to the right, and for this reason, the projection 380 of the piston assembly 300 will not leave the operating groove 400 unless the tool is used. The operating groove 400 is less deep than the assembly groove 395. Therefore, in this position, the piston assembly 300 can move far enough to the right to properly actuate the clutch F. Additionally, the piston assembly 300 prevents the clutch F from moving so far to the left that the retaining ring 315 leaves the assembly groove 390. Likewise, the expansion of the retaining ring 315 is prevented by a blocking surface 405 (see Figure 4). Fig. 3A and Fig. 3B) of the pressure plate 309 is prevented. When the clutch F rotates at high speed, a centrifugal force causes the retaining ring 315 to expand outwards (i.e., towards the upper side edge in Fig. 3) However, this expansion is stopped by the blocking surface 405. Consequently, it should be clear that this arrangement prevents the retaining ring 315 from leaving the mounting groove 390 when the piston assembly 300 is in the operating groove 400 (shown in Fig. 3A and Fig. 4), while the insertion of the retaining ring 315 is permitted when the piston assembly 300 is located in the assembly groove 395 (shown in Fig. 3B).

[0016] In contrast, and with reference to Fig. 3A and Fig. Figure 3B shows a more typical arrangement for a clutch, a piston, and a retaining ring in clutch D. Specifically, clutch D is held in position by a retaining ring 410 located in a mounting groove 415 and actuated by a piston 420 of a piston assembly 290. The retaining ring 410 is of the type that is compressed upon installation and can then expand back to its normal size. Accordingly, a groove 425 is provided in a pressure plate 430 of clutch D. When the retaining ring 410 is compressed, it fits into the groove 425, and when it expands, it moves into the mounting groove 415. A centrifugal force resulting from the rotation of clutch D will tend to cause the retaining ring 415 to expand outwards (i.e., towards the upper side edge). However, this expansion is stopped by the transmission shaft 301.Accordingly, it should be clear that in such an arrangement, an assembly groove and an operating groove are unnecessary, since there is sufficient space for installing the retaining ring 410, but there is no possibility for the retaining ring 410 to leave the assembly groove 415 due to centrifugal force. Conversely, in conjunction with the coupling F, the retaining ring 315 will tend to expand and leave the assembly groove 390 when rotating at high speed, unless the blocking surface 405 is provided. However, the blocking surface 405 simultaneously prevents the retaining ring 315 from being inserted into the assembly groove 390. Therefore, the assembly groove 395 is provided so that the piston assembly 300 and the coupling F can be pushed far enough to the left to allow the retaining ring 315 to be inserted.Unlike with clutch D, placing a groove similar to the groove 425 in the pressure plate 309 would allow the insertion of the retaining ring 315, but would also cause the retaining ring 315 to leave the mounting groove 390 at high speeds.

[0017] Now, reference is made to Fig. Figure 5, in which an alternative embodiment is shown in which a retaining ring holder 500 and a second retaining ring 505 are used to prevent the retaining ring 315 from leaving the mounting groove 390 due to centrifugal force. During installation, the retaining ring 315 expands, is inserted into a groove 510 in a pressure plate 309', and can then contract so that it enters the mounting groove 390. As explained above, a sufficiently large centrifugal force can cause the retaining ring 315 to leave the mounting groove 390. To prevent this possibility, the retaining ring holder 500 and the second retaining ring 505 are provided. The second retaining ring 505 is of the type that is compressed during installation and then expands upon release. Accordingly, the second retaining ring 505 is held in position by the pressure plate 309'.The retaining ring holder 500, on the other hand, is designed as a closed ring. The retaining ring holder 500 and the second retaining ring 505 hold the retaining ring 315 in position by preventing it from expanding after installation. In particular, the pressure plate 309' prevents the second retaining ring 505 from expanding due to centrifugal force. The second retaining ring 505 contacts the retaining ring holder 500 and holds it in position, and the retaining ring holder 500, in turn, contacts the retaining ring 315 and prevents it from expanding. Accordingly, the retaining ring 315 cannot leave the assembly groove 390 due to centrifugal force, and in this embodiment, there is no need for an assembly groove and an operating groove.

[0018] Fig.Figure 6 shows an additional embodiment in which a third retaining ring 600 is used instead of the retaining ring holder 500. As above, the retaining ring 315 is expanded, inserted into a groove 510' in a pressure plate 309", and can then contract so that it enters the mounting groove 390. To prevent the retaining ring 315 from leaving the mounting groove 390 due to centrifugal force, a second retaining ring 505' and a third retaining ring 600 are provided. Both the second retaining ring 505' and the third retaining ring 600 are of the type of retaining ring that is compressed during installation and then expands upon release. Accordingly, the second retaining ring 505' and the third retaining ring 600 are held in position by the pressure plate 309". Additionally, the third retaining ring 600 is prevented from leaving the groove 510' by the second retaining ring 505'.This prevents the retaining ring 315 from expanding and thus from leaving the mounting groove 390 by the third retaining ring 600, which itself is held in position by the pressure plate 309" and the second retaining ring 505'.

[0019] Based on the above, it should be clear that the present invention provides a transmission design that allows the installation of a retaining ring which expands during installation and prevents the retaining ring from moving after installation. Although the descriptions refer to preferred embodiments, it is easy to understand that numerous changes or modifications, both minor and major, could be made to the invention without departing from the concept of the invention. For example, the present invention can be used with both clutches and brakes. Furthermore, the transmission can include a higher or lower number of friction element arrangements, piston arrangements, planetary gear sets, and gear ratios. In general, only a limitation of the invention by the scope of the following claims is intended.

Claims

[1] Method for assembling a vehicle transmission (110) in a transmission housing, comprising: Insertion of a piston assembly (300); Placing a friction element arrangement on a transmission shaft (301); Insertion of a retaining ring (315); Widening of the retaining ring (315); Placing the retaining ring (315) near a mounting groove (390) formed in the transmission shaft (301); and Securing the friction element arrangement by means of the retaining ring (315) by enabling the retaining ring (315) to contract and enter the mounting groove (390); wherein the retaining ring (315) defines a first retaining ring (315) and the method further comprises the following: Inserting a second retaining ring (505); Compressing the second retaining ring (505); Placing the second retaining ring (505) near a pressure plate (309) of the friction element assembly; and Securing the first retaining ring (315) by the second retaining ring (505), by allowing the second retaining ring (505) to expand so that the second retaining ring (505) touches the pressure plate (309), Inserting a retaining ring holder (500) or a third retaining ring (600) before inserting the second retaining ring (505); and Placing the retaining ring holder (500) or the third retaining ring (600) in contact with the first retaining ring (315). [2] Method for assembling a vehicle transmission (110) in a transmission housing, comprising: Insertion of a piston assembly (300); Placing a friction element arrangement on a transmission shaft (301); Insertion of a retaining ring (315); Widening of the retaining ring (315); Placing the retaining ring (315) near a mounting groove (390) formed in the transmission shaft (301); and Securing the friction element arrangement by means of the retaining ring (315) by enabling the retaining ring (315) to contract and enter the mounting groove (390); wherein the piston assembly (300) has a piston cap (350) with a projection (380); a gear element (385) with an assembly groove (395) and an operating groove (400), wherein the operating groove (400) is less deep than the assembly groove (395); wherein during assembly a piston assembly (300) is inserted into the gearbox (110), the projection (380) is aligned with the assembly groove (395) and then inserted into it; and Moving the piston assembly (300) from an assembly position to an operating position after securing the friction element assembly by the retaining ring (315); wherein as soon as the projection (380) leaves the assembly groove (395), the piston assembly (300) is rotated until the projection (380) is aligned with the operating groove (400). [3] The method of claim 2, further comprising: Preventing the retaining ring (315) from leaving the mounting groove (390) due to a centrifugal force by placing a blocking surface (405) of a pressure plate (309) of the friction element arrangement, so that the retaining ring (315) cannot expand sufficiently to leave the mounting groove (390). [4] Method for placing a vehicle transmission (110) in a vehicle, wherein the method for placing the vehicle transmission (110) in the vehicle comprises a method for assembling the vehicle transmission (110) in the transmission housing according to any one of claims 1 to 3.

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