Pressure feed to a shaft

A hydraulic fluid feed mechanism that feeds into a shaft (1) of a transmission having a hydraulic control device, by which the hydraulic feed mechanism can be supplied with hydraulic fluid, comprising a transmission housing (3) in which the shaft is held, and a housing cover (7) that is equipped with feed bores (8, 9), by which the hydraulic fluid is fed from the hydraulic control device into the shaft (1). A hydraulic fluid line (12) is positioned between the hydraulic or pneumatic control device and a feed bore (9) in the housing cover (7) that extends parallel to the shaft (1), with this hydraulic fluid line being comprised of a fitting (13) and a tube (14) which is permanently inserted into the fitting at nearly right angles, forming a pressure-tight seal. The fitting (13) is pushed through a transmission housing bore (15) that extends parallel to the shaft (1), is separably inserted into the feed bore (9) forming a pressure-tight seal, and is axially mounted to the transmission housing (3) by a sealing ring (20).

FIELD OF THE INVENTION

The Invention relates to a hydraulic fluid feed mechanism feeding into a shaft of a transmission, especially into a variable speed gear shaft of a continuously variable transmission.

BACKGROUND OF THE INVENTION

Hydraulic fluid feed mechanisms that lead into a rotating shaft mounted in a transmission housing are known in a multitude of designs. For example, DE 199 21 749 A1 describes a hydraulic fluid feed mechanism that feeds into a primary shaft of a variable speed belt gear of a continuously variable, automatic transmission. The primary shaft is mounted on a bearing in a transmission housing. A bearing bore extending through the wall of the transmission housing in the area around the bearing is planned. The bearing is mounted axially in the transmission housing with a sealing ring. An electric-hydraulic control device is provided to supply hydraulic fluid to the variable speed gear; this device is oriented perpendicularly to the bearing bore on the end surface of the transmission housing and simultaneously serves to cover the bearing bore in the transmission housing. The supply of hydraulic fluid from the electric-hydraulic control device into an axial bore in the primary shaft is accomplished by a plain conduit system, in which two tubes, one inside the other, are inserted into a variable stage bore of the electric-hydraulic control device creating an oil-tight connection; both tubes extend into the axial bore in the primary shaft, and each of the two tubes is sealed against the rotation of the primary shaft by a sleeve bearing. The outer tube is axially fastened to the electric-hydraulic control device by a retaining panel. The inner tube is not secured in any way.

In DE 199 32 339 A1, of the applicant is a hydraulic fluid feed mechanism for a variable speed gear shaft of a continuously variable transmission became known, in which the supply of hydraulic fluid by a hydraulic transmission control device is accomplished by hydraulic feed lines located within a transmission housing, and by hydraulic feed lines located in a housing cover, into an axial variable bore in the variable speed gear shaft. The variable speed gear shaft is mounted in the transmission housing on at least one bearing, wherein the bearing is positioned within a corresponding bearing bore in the transmission housing and is fastened axially in this bearing bore by a retaining panel. The bearing bore is designed as a through bore into which the variable speed gear shaft extends. The bearing bore[hole] is covered by the housing cover. A tubular projection from the housing cover extends into the axial variable bore of the variable speed gear shaft, and is sealed against the rotating variable speed gear shaft by a rectangular-section ring. The hydraulic fluid is fed from a channel in the transmission housing into a channel in the housing cover that runs parallel to the shaft; from there it is fed into a boring in the housing cover that is oriented perpendicularly to the shaft and from there into a boring in the housing cover that is oriented perpendicularly to the shaft and, finally, by an inner axial boring in the tubular projection of the housing cover into the variable speed gear shaft. A flat packing seals the hydraulic fluid channels in the partition between the transmission housing and the housing cover from the outside.

The object of the present invention is to further develop a hydraulic fluid feed mechanism leading from a hydraulic or pneumatic transmission control device into a shaft of a transmission, especially for applications in which the pressure discharge from the hydraulic or pneumatic transmission control device to the shaft does not take place in the immediate vicinity of the shaft, while taking into consideration seal tightness problems, especially at high pressures.

Base on the known state of the art, the hydraulic fluid mechanism feeding into the shaft of a transmission comprises a hydraulic or pneumatic control device by which the hydraulic feed mechanism can be filled with hydraulic fluid; a transmission housing in which the shaft is positioned, and a housing cover, which is equipped with feed bores by which the hydraulic fluid is introduced into the shaft by the hydraulic or pneumatic control device.

SUMMARY OF THE INVENTION

According to the invention, it is recommended that the hydraulic line be positioned between the hydraulic or pneumatic control device and a feed bore in the housing cover be oriented parallel to the shaft; the hydraulic line is comprised of a fitting and a tube that is permanently fastened to the fitting, producing a pressure-proof seal. Further, the tube is inserted into the fitting at nearly right angles. The fitting is inserted all the way through a accordingly designed bore in the transmission housing that is oriented parallel to the shaft and is inserted into the feed bore fore part surface of the housing cover. The side of the tube that faces away from the fitting is connected to the hydraulic fluid outlet channel of the hydraulic or pneumatic control device, producing a detachable pressure-proof seal. The hydraulic line is fastened axially to the transmission housing.

The hydraulic line can be axially mounted by a sealing ring, which becomes engaged in a correspondingly designed groove in the fitting. In this case the fitting is advantageously equipped with a heel designed as a buffer, which is supported by the wall of the transmission housing when it is pushed through the bore in the transmission housing, wherein the groove is positioned in the area of the transmission housing wall that is opposite the relief. Once the fitting has been pushed through the bore in the transmission housing, the sealing ring becomes engaged in the groove of the fitting, thus fastening the hydraulic line axially in the transmission housing.

In another design of the axial mounting of the hydraulic line in the transmission housing, a snap ring can be provided. Once the fitting has been pushed through the bore in the transmission housing, the snap ring becomes engaged in corresponding grooves in the transmission-housing bore and in the fitting.

With the design of the hydraulic fluid feed mechanism specified in the invention, a secure, pressure-proof connection between the hydraulic or pneumatic control devices and the shaft is advantageously ensured, even under very high pressure, since the pressure-dependent supporting forces will not permit an inadmissible axial shift in the hydraulic line. It is not necessary for the hydraulic or pneumatic control device to be located immediately adjacent to the shaft. The parallel orientation of the shaft and the housing cover and the separable coupling of the hydraulic line to the housing cover facilitate the assembly and disassembly of the housing cover. Further, the assembly sequence for the hydraulic or pneumatic control device within the transmission housing can be implemented independent of the assembly of the hydraulic fluid feed mechanism from the control device to the shaft.

In one design of the invention, it is proposed that the tube and the fitting for the hydraulic fluid line be soldered, welded, or glued together. This will reduce the risk of leakage from this joint, both directly during assembly and during operation as a result of pressure changes and vibration, as compared with a pressure connection between the tube and the fitting.

The above-described hydraulic fluid feed mechanism is particularly well suited for use as a hydraulic fluid feed mechanism for a variable speed gear shaft in a continuously variable automatic transmission. Because in such a system relatively large flow volumes, at times under high pressure, must be introduced into the rotating shaft, an axial introduction of hydraulic fluid into the rotating variable speed shaft is favorable. The axial space that is required in the hydraulic fluid feed mechanism, specified in the invention, at the end surface of the variable speed shaft where the hydraulic fluid is introduced is relatively small and is limited to the geometric dimensions of the bearing cover, with allowances for the necessary cross-sections and wall thicknesses of the hydraulic fluid channels located within the bearing cover. The hydraulic control device, by which the variable speed shaft is supplied with hydraulic fluid, can be oriented parallel to the variable speed shaft, thus decreasing the necessary length of the transmission.

Of course, the hydraulic fluid feed mechanism is universally applicable in a transmission shaft, and is not restricted to use as a hydraulic fluid feed mechanism in a variable speed gear shaft as described by way of example above.

DETAILED DESCRIPTION OF THE INVENTION

As a design example of a hydraulic fluid feed mechanism in a transmission shaft, as specified in the invention, the single diagram shows a hydraulic fluid feed mechanism in a rotating, variable speed gear shaft of a continuously variable transmission.

TheFIG. 1denoting the shaft of a transmission in the design example shows a variable speed shaft of the continuously variable automatic transmission. The shaft1is held by a bearing5—in the design example of an antifriction bearing—in a transmission housing3. The shaft1extends through the transmission housing3in the area of a bearing bore4intended for the bearing5. The bearing bore4is covered by a housing cover7. The bearing5is axially fastened to the shaft1by a shaft nut and in the transmission housing3by a retaining panel6. Of course, other designs for mounting the shaft1within the transmission housing3are known to the-state-of-the-art experts in the field. The shaft1is equipped with an axial shaft bore2at the end of the shaft that faces the bearing cover7which, in the example, is designed as a variable bore and by which hydraulic fluid is introduced from a hydraulic or pneumatic control device in the transmission, not illustrated here, into the shaft1. The feed of hydraulic fluid in this axial shaft bore2is implemented by several feed bores8and9, which are located in the bearing cover7. In the design example shown, the feed bore8extends within the housing cover7perpendicular to the shaft1, and opens up at one end by a tubular section10of the housing cover7into the axial shaft bore2, and at the other end within the housing cover in the feed bore9, which extends parallel to the shaft1. This feed bore9is sealed against the outside area of the transmission, and opens up in the area of the face surface11of the housing cover7that faces toward the bearing bore4, within the transmission housing3.

According to the invention, a hydraulic line12is located between the feed bore9in the housing cover7that extends parallel to the shaft1and a hydraulic fluid outlet channel from the hydraulic or pneumatic control device of the transmission, which is not illustrated here; this hydraulic line comprises a fitting13and a tube14and is mounted from an inner area16of the transmission housing3outward. Here, the fitting13and tube14are permanently attached to one another, in a pressure-tight seal, for example by a pressure seal, soldering, welding, or an adhesive connection. The side of the tube14that faces away from the fitting13is connected by a detachable pressure-tight connection to the hydraulic fluid outlet channel of the hydraulic or pneumatic control device of the transmission, for example by a socket connection sealed with a gasket. The side of the fitting13opposite the tube14is separably connected in a pressure-tight seal to the feed bore9in the housing cover7, which extends parallel to the shaft.

In addition, in the wall18of the transmission housing3that borders the face surface11of the housing cover7facing the bearing bore4, a separate transmission housing bore15that extends parallel to the shaft1is provided, through which the fitting13is pushed from the inside space16of the transmission housing3and, during assembly, is inserted into the feed bore9of the housing cover7, forming a removable, pressure-tight seal; the feed bore in the housing cover also extends parallel to the shaft1. In the design example, in an assembled state, the fitting13extends into the feed bore9and is sealed by a gasket21against the diameter of the feed bore9. Of course, the connection between the fitting13and the feed bore9may also be designed differently, for example as a flat seat with a flat seal.

To prevent any unintentional axial shifting of the hydraulic line12during operation, especially when it is filled with hydraulic fluid, the hydraulic fluid line12is axially fastened to the transmission housing3.

In one of the first designs of the axial mounting of the hydraulic fluid line12it was proposed that the fittings13for the hydraulic fluid line12be fastened by a sealing ring20to the wall18of the transmission housing2[sic]. To this end, the fitting13is equipped with a heel17, which rests in the area of the transmission housing bore15against the wall18of the transmission housing3. The fitting13is further equipped with a groove19, which is positioned on the side of the housing wall18opposite the heel17of the fitting13. Once the fitting13of the hydraulic fluid line12has been pushed through from the inside space16of the transmission housing3, through the transmission housing bore15, the sealing ring20moves from the side of the housing wall18that faces the housing cover7, and becomes engaged in the groove19of the fitting13, thus fastening the hydraulic fluid line12axially on the wall of the housing18.

In a second design of the axial mounting of the hydraulic fluid line12it is proposed that the hydraulic fluid line12be fastened by a snap ring in the wall18of the transmission housing2. To this end, the fitting13of the hydraulic fluid line12is equipped with a radial groove on its outer surface, in a section that lies in the area of the transmission housing bore15that extends parallel to the shaft1. Furthermore, a radial groove is located in the transmission housing bore15in the housing wall18, which extends parallel to the shaft1.

Prior to assembly of the hydraulic fluid line12, the snap ring is emplaced either within the radial groove in the transmission housing bore15, or in the radial groove in the fitting13. If the snap ring is emplaced in the radial groove in the transmission housing bore15prior to assembly of the hydraulic fluid line then, when the fitting13in the hydraulic fluid line12is pushed through the transmission housing bore15, the snap ring is first spread apart and then snapped into the radial groove in the fitting13. If the snap ring is emplaced in the radial groove in the fitting13of the hydraulic fluid line12prior to assembly of the hydraulic fluid line12, then when the fitting13is pushed through the transmission housing bore15, the snap ring is first compressed and then snaps into the radial groove in the transmission housing bore15. In both cases, after assembly of the hydraulic fluid line12the snap ring remains engaged in both grooves, thus ensuring an axial mounting of the hydraulic fluid line12relative to the transmission housing3.

Reference Numerals

1Shaft2Axial Shaft Bore3Transmission Housing4Bearing Bore of the Transmission Housing5Bearing6Retaining Panel for the Bearing7Housing Cover8,9Feed Bores in Housing Cover10Section of Housing Cover11End Surface of Housing Cover12Hydraulic Fluid Line13Fittings for Hydraulic Fluid Line14Tube for Hydraulic Fluid Line15Transmission Housing Bore16Inside Space of Transmission Housing17Shoulder of the Fitting18Transmission Housing Wall19Groove for Fitting20Sealing Ring21Gasket for Fitting