Shafts for motor vehicle transmissions

Abstract

A shaft (W) for a motor vehicle transmission (G), wherein the shaft (W) has four axial holes (B1, B2, B3, B4), which are configured to guide fluid within the shaft (W), wherein the central axis of each of the four holes (B1, B2, B3, B4) is arranged to be spaced apart from the rotation axis (WA) of the shaft (W); and wherein the radial spacing (r1) between the central axis of at least two of the four holes (B1, B2, B3, B4) and the rotation axis (WA) is different from the radial spacing (r2) between the central axis of one of the remaining holes and the rotation axis (WA); and a transmission (G) for a motor vehicle, which has such a shaft (W).

Description

Technical Field

[0001] The invention relates to a shaft for a motor vehicle transmission and to a transmission for a motor vehicle having such a shaft. Background Art

[0002] It is known in the prior art for motor vehicle transmissions to supply hydraulic fluid to elements of the transmission via bores extending in the transmission shaft. Thus, DE 10 2009 014 731 A1 shows a multi-speed transmission whose drive shaft has four bores.

[0003] In such a design, it is important that the shaft has sufficient strength despite the holes. The outer diameter of the shaft should be kept as small as possible in order to keep the diameter of the bearing and the diameter of the sealing element that engages the shaft small. Furthermore, it must be taken into account that pressures of different magnitudes may act in the holes. If the wall thickness between the holes is too small, cracks may occur between the holes during operation and thus hydraulic short circuits may occur. Therefore, tolerances must be taken into account when producing the holes, because, especially in the case of relatively deep holes, a deviation of the drilling axis can significantly reduce the wall thickness between the holes. Summary of the invention

[0004] The object of the invention is therefore to provide a shaft which, despite having four axial holes, has a high strength.

[0005] A shaft for a motor vehicle transmission is proposed, the shaft having four axial holes. Each of the four holes is configured to guide a fluid in the shaft. According to the invention, the central axis of each of the four holes is arranged spaced apart from the axis of rotation of the shaft. In addition, the radial spacing between the central axis of at least two of the holes and the axis of rotation of the shaft is different from the radial spacing between the central axis of one of the remaining holes or the remaining holes and the axis of rotation of the shaft. In other words, at least two of the four holes are arranged on at least one diameter of the shaft cross section that is different from the remaining hole or the remaining holes. By means of this variable radial distribution of the holes, the wall thickness between the holes and the annular area between the outer diameter of the shaft and the hole can be optimized so as to ensure the strength required for the shaft.

[0006] Preferably, the radial spacing between the center axes of exactly two of the four holes and the rotation axis of the shaft is the same. Preferably, the radial spacing between the center axes of the remaining two holes and the rotation axis of the shaft is the same. In this design, the four holes can be evenly arranged on the cross section of the shaft, whereby the strength of the shaft can be optimized.

[0007] Preferably, the hole diameters of at least two of the four holes differ from one another.The strength of the shaft can be optimized by varying the hole diameters in combination with at least partially different spacings of the holes from the axis of rotation.

[0008] Particularly preferred is a design in which two of the four holes have the same hole diameter. A clearly preferred design results in two of the four holes having the same hole diameter. This design enables a uniform arrangement of the four holes that is advantageous for strength.

[0009] Preferably, the hole diameters of the four holes are inversely proportional to the radial spacing between the central axes of the four holes and the rotation axis of the shaft. In other words, the hole diameters of the holes arranged closer to the rotation axis are larger than the hole diameters of the holes further away from the rotation axis. It should be noted that the inverse relationship between the spacing between the holes and the rotation axis and the hole diameters can be linear, but does not necessarily have to be linear.

[0010] Preferably, the four holes are arranged so that the radially outermost point of each of the four holes has the same radial spacing with the axis of rotation of the shaft. This arrangement is conducive to evenly arranging the holes in the shaft cross section, which is beneficial to the strength of the shaft.

[0011] The shaft can be a component of a transmission for a motor vehicle. Different types of transmissions are conceivable, such as automatic transmissions, dual clutch transmissions, transmissions with continuously variable transmission ratios or automated manual transmissions. The transmission can use spur gear stages and / or planetary gear sets to form the gears.

[0012] Preferably, at least one of the four holes is arranged for supplying oil to a hydraulic actuation mechanism of a clutch of the transmission.

[0013] The transmission preferably comprises a hydraulic torque converter having a lock-up clutch, i.e. a clutch for switchably connecting the pump wheel and the turbine wheel of the torque converter. In addition, the transmission can have a further clutch connected upstream of the torque converter. The shaft mentioned at the outset is particularly suitable for such an application, since hydraulic fluid can be conducted to the hydraulic actuation of the lock-up clutch and the further clutch by means of the shaft.

[0014] The first of the four holes can be arranged, for example, for supplying oil to the annular space of the torque converter or for draining oil from the annular space of the torque converter. The second of the four holes can be arranged for supplying lubricating oil to at least one component of the transmission, for example for lubricating a rolling bearing. The third of the four holes can be arranged for supplying oil to a hydraulic actuation mechanism of another clutch. The fourth of the four holes can be arranged for supplying oil to a hydraulic actuation mechanism of a lockup clutch.

[0015] If the hydraulic actuation mechanism of the further clutch has a pressure balance chamber for compensating rotational forces, the second of the four bores is preferably used to supply oil to the pressure balance chamber.

[0016] The further clutch is preferably designed as a wet-running multi-plate clutch. In this case, oil is supplied at least partially via the second of the four holes for cooling and lubricating the further clutch. In particular, a further oil supply path may also be provided to cool the further clutch.

[0017] Preferably, the shaft in which the four holes are arranged is connected to the turbine of the torque converter. This is a permanent, ie non-switchable, connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments of the present invention are described in detail below with the aid of the accompanying drawings. In the accompanying drawings:

[0019] Figure 1 A simplified diagram of a motor vehicle powertrain having a transmission is shown;

[0020] Figure 2 and Figure 3 each showing a simplified cross-sectional view of a section of a transmission; and

[0021] Figure 4 A cross-sectional view of a shaft of a transmission is shown. DETAILED DESCRIPTION

[0022] Figure 1 The powertrain of a motor vehicle is schematically shown. The powertrain has a combustion engine VM, a transmission G with a shaft W, and a differential AG. The combustion engine VM is connected to the input shaft AN of the transmission G. In this connection, a plurality of transmissions may be arranged. Figure 1 The output shaft of the transmission G is connected to the differential AG, for example, via a cardan shaft. The power applied to the output shaft is distributed to the drive wheels DW of the motor vehicle by means of the differential AG. Figure 1 The drive train shown in is to be regarded as an example only. Instead of the shown structure of a drive train oriented longitudinally to the driving direction of the motor vehicle, it is also conceivable to use the transmission G in a drive train oriented transversely to the driving direction. The differential AG can be integrated into the housing GG of the transmission G.

[0023] The transmission G has a hydraulic torque converter TC, which has a pump wheel P, a turbine T, a stator L and a lock-up clutch WK. The pump wheel P is connected to the turbine T by closing the lock-up clutch WK. The stator L is supported on a plate ZP fastened to the housing GG via a free wheel F. The turbine T is connected to the shaft W. The transmission G also has an electric machine EM, which has a non-rotatable stator S and a rotatable rotor R. The rotor R is connected to the pump wheel P and can be connected to the input shaft AN via a further clutch K0.

[0024] The transmission G has a hydraulic unit HY. The hydraulic unit HY has a pump (not shown) and a hydraulic shifting device (not shown). The pump can supply hydraulic fluid to the hydraulic shifting device. The hydraulic shifting device is configured to distribute the hydraulic fluid to different hydraulic consumers of the transmission G as required. The correspondingly distributed volume flow can be supplied to the torque converter TC via the plate ZP to actuate the lockup clutch WK, actuate the further clutch K0 and lubricate different components of the transmission G and actuate the shifting elements SE1, SE3 of the transmission G. For this purpose, the plate ZP has a first hydraulic connection HY1 to the hydraulic unit HY and a second hydraulic connection HY2 to the shaft W.

[0025] With the aid of the transmission G, different gear stages can be provided between the shaft W and the output shaft. For this purpose, the transmission G has a plurality of planetary gear sets, which are collectively referred to as gear sets RS. The shaft W serves as a drive shaft for the gear sets RS. The transmission G has a plurality of shifting elements SE1, SE2, SE3, SE4, SE5. The shifting elements SE1, SE2, SE3, SE4, SE5 work together with the planetary gear sets to form the gear stages of the transmission G. Figure 1 The transmission G shown in FIG. 1 is to be regarded as an example only. Instead of a planetary gear set, a spur gear set can be used, for example, to form the gears.

[0026] Figure 2 A simplified sectional view of a detail of a transmission G is shown. The lockup clutch WK is designed as a wet-running clutch and is actuated by means of a piston WKK which is connected to a pressure chamber WKP. The piston WKK is guided between two seals WKD1, WKD2. The pressure chamber WKP is partially delimited by a radial wall X which is connected to the pump wheel P. The gap between the wall X and the shaft W is sealed by a seal DX.

[0027] The other clutch K0 is actuated by a piston K0K which is in communication with the pressure chamber K0P. The piston K0K is guided between two seals K0D1 and K0D2. The pressure chamber K0P is partially defined by a wall X. A pressure balance chamber K0A is provided to balance the rotational forces acting in the pressure chamber K0P. For this purpose, a baffle plate is provided which is fastened to the input shaft AN and is sealed relative to the piston K0K by a seal K0AD. The piston K0K is arranged between the pressure chamber K0P and the pressure balance chamber K0A. The shaft W is rotatably supported on the input shaft AN by means of a rolling bearing WL. A roller bearing WL may be provided at Figure 2 Additional rolling bearings not shown are used to support shaft W and input shaft AN.

[0028] exist Figure 2 The oil supply to the annular space of the torque converter TC and the oil supply to the rolling bearing WL are shown in FIG. Here, the section plane of the shaft W is selected so that the bore B1 and the bore B2 can be seen. The bore B1 is used to supply oil to the annular space of the torque converter TC. The oil is supplied to the bore B1 via radial bores B1_in in the shaft W, wherein the oil can escape from the shaft W via radial bores B1_out. By Figure 2 The plate ZP not shown in the figure supplies oil to the radial bore B1_in. The oil is supplied to the lock-up clutch WK and the hydraulic path between the pump wheel P, the turbine T and the stator L via the radial bore B1_out. The oil can be drained from the annular space of the torque converter TC, for example, by means of a gap which is arranged between the housing of the torque converter TC connected to the pump wheel P and the shaft WLR connected to the stator L. Figure 2 The corresponding oil paths are indicated by arrows in . Downstream of the hole B1_out, the hole B1 is closed by a closing portion B1S.

[0029] The bore B2 is used to supply oil to the rolling bearing WL, to fill the pressure balance chamber K0A and to supply oil to the further clutch K0. The oil is supplied to the bore B2 via radial bores B2_in in the shaft W and overflows again at openings B2_out in the end side of the shaft W. Figure 2 The plate ZP not shown in the figure supplies oil to the radial holes B2_in. The oil is thrown radially outward toward the inside of the input shaft AN by the rotation of the shaft W. From there, the oil flows through the rolling bearing WL in the direction of the seal K0D2. The oil reaches the pressure balance chamber K0A through the axial gap between the axial end of the input shaft AN and the piston K0K. If the pressure balance chamber is filled with enough oil, the oil is supplied to another clutch K0. Figure 2 The corresponding oil paths are indicated by arrows.

[0030] Figure 3Another simplified cross-sectional view of a portion of the transmission G is shown, which is generally similar to Figure 2 The view shown corresponds to the view shown. The section plane of the axis W has now been selected so that the bore B3 and the bore B4 can be seen. The bore B3 is used to supply oil to the pressure chamber K0P. The further clutch K0 is hydraulically actuated by applying pressure to the pressure chamber K0P. The oil is supplied to the bore B3 via radial bores B3_in. By Figure 3 The plate ZP not shown in the figure supplies oil to the radial hole B3_in. The oil enters the pressure chamber K0P through the radial hole B3_out. Downstream of the hole B3_out, the hole B3 is closed by the closing portion B3S. Figure 3 The corresponding oil paths are indicated by arrows.

[0031] The bore B4 is used to supply oil to the pressure chamber WKP. The lockup clutch WK is hydraulically actuated by applying pressure to the pressure chamber WKP. The oil is supplied to the bore B4 via the radial bore B4_in. Figure 3 The plate ZP not shown in the figure supplies oil to the radial bore B4_in. The oil enters the pressure chamber WKP through the radial bore B4_out. Downstream of the bore B4_out, the bore B4 is closed by a closing portion B4S. Figure 3 The corresponding oil paths are indicated by arrows.

[0032] It should be pointed out that in Figure 2 and Figure 3 The illustrations in are schematic only and do not represent the complete structure. Figure 2 and Figure 3 The illustration in particular serves to illustrate the supply of fluid via bores B1 to B4 of the shaft W to the torque converter TC, the pressure chambers WKP, K0P, the pressure equalization chamber K0A, the rolling bearing WL and the further clutch K0.

[0033] Figure 4 A cross-sectional view of a shaft W is shown. The shaft W is centrally supported rotatably about an axis of rotation WA and has four axial holes B1, B2, B3, B4. On the one hand, the holes B1, B2 have the same hole diameter and the holes B3, B4 have the same hole diameter. The hole diameter of the holes B1, B2 is larger than the hole diameter of the holes B3, B4. Here, the radial spacing between the center axis of the holes B1, B2 and the axis of rotation WA, which is designated r1, is smaller than the radial spacing between the center axis of the holes B3, B4 and the axis of rotation WA, which is designated r2. The four holes B1, B2, B3, B4 are arranged here so that the radial spacing between the axis of rotation WA and the radially outermost point of each of the four holes B1, B2, B3, B4, which is designated r3, is the same. Figure 4 The illustrations in are for illustration purposes only and are not to scale.

[0034] List of Reference Numerals

[0035] VM combustion engine

[0036] G-Transmission

[0037] AN input shaft

[0038] GG Shell

[0039] W-axis

[0040] WA axis rotation axis

[0041] B1 axial hole

[0042] B2 axial hole

[0043] B3 axial hole

[0044] B4 axial hole

[0045] r1, r2, r3 radial spacing

[0046] B1_in radial hole

[0047] B1_out radial hole

[0048] B2_in radial hole

[0049] B2_out opening

[0050] B3_in radial hole

[0051] B3_out radial holes

[0052] B4_in radial hole

[0053] B4_out radial holes

[0054] B1S Enclosure

[0055] B3S sealing part

[0056] B4S Sealing Section

[0057] TC Torque Converter

[0058] P Pump

[0059] T-Turbine

[0060] L Guide Wheel

[0061] WLR guide wheel shaft

[0062] F Freewheel

[0063] WK Lock-up Clutch

[0064] WKP Pressure Chamber

[0065] WKK Piston

[0066] WKD1 seals

[0067] WKD2 seals

[0068] X wall

[0069] DX Seals

[0070] K0 Additional Clutch

[0071] K0D1 seal

[0072] K0D2 seals

[0073] K0P Pressure Chamber

[0074] K0K Piston

[0075] K0A Pressure Balance Chamber

[0076] K0AD seals

[0077] EM Electric Machine

[0078] S rotor

[0079] R-Stator

[0080] WL rolling bearings

[0081] HY Hydraulic Unit

[0082] HY1 first hydraulic interface

[0083] HY2 second hydraulic port

[0084] RS Gear Set

[0085] SE1 shift element

[0086] SE2 shift elements

[0087] SE3 shift elements

[0088] SE4 shift elements

[0089] SE5 shift elements

[0090] AG differential

[0091] DW drive wheel

Claims

1. A shaft (W) for a motor vehicle transmission (G), wherein: The shaft (W) has four axial holes (B1, B2, B3, B4), which are configured to guide a fluid in the shaft (W). Characterized in that the central axis of each of the four holes (B1, B2, B3, B4) is arranged spaced apart from the rotation axis (WA) of the shaft (W); And the radial spacing between the center axes of exactly two opposite holes with a first hole diameter among the four holes (B1, B2, B3, B4) and the rotation axis (WA) is different from the radial spacing between the center axes of the remaining two opposite holes with a second hole diameter and the rotation axis (WA), the radial spacing between the center axes of exactly two opposite holes with the first hole diameter among the four holes (B1, B2, B3, B4) and the rotation axis (WA) is the same, and the radial spacing between the center axes of the remaining two opposite holes with the second hole diameter and the rotation axis (WA) is the same, the first hole diameter is different from the second hole diameter, two opposite holes among the four holes are respectively arranged symmetrically with respect to a straight line extending through the center axes of the remaining two opposite holes, so that the four holes are evenly arranged on the cross section of the shaft, thereby optimizing the strength of the shaft, and the strength of the shaft can be optimized by combining changing the hole diameter with at least partially different spacings of the holes to the rotation axis, and The hole diameters of the four holes (B1, B2, B3, B4) and the radial spacing between the central axes of the holes (B1, B2, B3, B4) and the rotation axis (WA) are inversely proportional, and The four holes (B1, B2, B3, B4) are arranged such that the radial spacing between the radially outermost point of each of the four holes (B1, B2, B3, B4) and the rotation axis (WA) is the same.

2. A transmission (G) for a motor vehicle, characterized in that A shaft (W) according to claim 1 is provided.

3. The transmission (G) according to claim 2, characterized in that: At least one of the four holes (B1, B2, B3, B4) of the shaft (W) is configured to supply oil to a hydraulic actuation mechanism of a clutch of the transmission (G).

4. The transmission (G) according to claim 2, characterized in that: The transmission (G) has a torque converter (TC) with a lockup clutch (WK) and a further clutch (K0) connected upstream of the torque converter (TC).

5. The transmission (G) according to claim 4, characterized in that: - a first hole of the four holes in the shaft (W) is arranged for supplying oil to or draining oil from a hydraulic path of the torque converter (TC); - a second hole of the four holes in the shaft (W) is arranged for supplying lubricating oil to at least one component of the transmission (G); - a third of the four holes in the shaft (W) is arranged for supplying oil to a hydraulic actuation mechanism of the further clutch (K0); and - A fourth hole of the four holes in the shaft (W) is provided for supplying oil to a hydraulic actuation mechanism of the lock-up clutch (WK).

6. The transmission (G) according to claim 5, characterized in that The second of the four bores is also provided for supplying a pressure balance chamber (K0A) of the hydraulic actuating mechanism of the further clutch (K0).

7. The transmission (G) according to claim 5 or 6, characterized in that: The further clutch (K0) is designed as a wet-running multi-disk clutch, wherein cooling and lubricating oil is supplied to the further clutch (K0) by means of a second bore of the four bores.

8. The transmission (G) according to claim 5 or 6, characterized in that: The shaft (W) is connected to a turbine (T) of the torque converter (TC).

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