Transmission output bearings with intermediate speedometer sensor

Abstract: An output bearing assembly of a transmission includes a housing (38), and a pair of tapered roller bearings (26,28). At least one speedometer sensor (25) is mounted between the bearings. The arrangement allows the output bearings to be spaced axially by a relatively great distance.

Description: BACKGROUND OF THE INVENTION This invention generally relates to a vehicle transmission according to the preamble of claim 1. A transmission of a vehicle typically includes a main section and an auxiliary section which each contain gears to provide several speed ratios on an output shaft. An output bearing assembly mounts the output shaft beyond the auxiliary section. Typically, the output bearing assembly includes a pair of tapered output bearings supporting the output shaft relative to the housing of the auxiliary section. Part of the function of the output bearing assembly is to support and limit radial displacement of the output shaft. Space constraints typically require that the two output bearings be placed relatively close to each other. Because the bearings are in close proximity, conventional output bearings may allow undesirable radial displacements of the output shaft. In addition, the typical transmission of a vehicle includes a speedometer rotor and a speedometer sensor both located beyond the output bearing assembly. This is known from US-A-5 293 787 which defines the closest prior art. The speedometer sensor measures the rotational speed of the speedometer rotor which is mounted on the output shaft. The sensed rotational speed is used as an indication of vehicle speed. It would be desirable to provide a transmisson which is better able to reduce radial displacement of the output shaft. SUMMARY OF THE INVENTION This invention provides a vehicle transmission in which a pair of output bearings are spaced apart and at least one speedometer sensor is mounted between the two output bearings. Generally, by placing the sensor between the bearings, the bearings may be separated by a greater distance without any necessary increase in the total length of the transmission. Preferably, an output bearing cup spacer integral with a housing of the auxiliary section spaces the bearings. In a second embodiment the output bearing cup spacer is a separate part from the housing. Both the output bearing cup spacer and the housing of the auxiliary section are spaced radially about an output shaft. The bearings are preferably tapered roller bearings. The output bearing cup spacer is positioned between outer races of the output bearings and a speedometer rotor is mounted around the output shaft between inner races of the output bearings. Most preferably, the spacer extends radially inwardly beyond an outermost surface of the outer races of the bearings. At least one speedometer sensor is mounted with a first end extending through the bearing cup spacer and spaced adjacent to the speedometer rotor. The speedometer sensor typically includes a set of external threads to be received in an internally threaded hole provided in the auxiliary section housing. A washer and a nut are threaded onto the speedometer sensor. The speedometer sensor is then threaded into the housing to a predetermined depth and then the nut and washer are tightened against the housing to lock the speeedometer sensor in place. The speedometer sensor is capable of detecting the rotational speed of the speedometer rotor and to thereby enable the speed of the vehicle to be calculated. The invention provides an output bearing cup spacer for separating the output bearings of the output bearing assembly in the transmission of a vehicle. This increases the distance between the output bearings such that radial displacement of the output shaft is reduced. The total length of the transmission is not increased since the space for mounting the sensor is now between the bearings. These and other features and advantages of this invention will become more apparent to those skilled in the art from the following detailed description of the presently preferred embodiment. The drawings that accompany the detailed description can be described as follows. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is a schematic diagram illustrating the components of the prior art vehicle transmission. Figure 1B is a cross-sectional view of a first embodiment of the invention shown mounted on a half-view of an output shaft of a transmission. Figure 2 is a cross-sectional illustration taken along lines 2-2 from Figure 1B. Figure 3 is a cross-sectional view of a second embodiment of the invention shown mounted on a half-view of an output shaft of a transmission. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1A schematically illustrates a known vehicle transmission 10 including a main section 12, an auxiliary section 14, an output bearing assembly 16, and a yoke 18. A speedometer sensor 20 is able to detect the rotational speed of a speedometer rotor 22 mounted around an output shaft 24 which extends through the components and is fixed to the yoke 18. The speedometer sensor 20 and the speedometer rotor 22 are spaced axially beyond output bearing assembly 16 and auxiliary section 14. Figure 1B is a cross-sectional view of a first embodiment of the invention mounted on a half-view of the output shaft 24 of the transmission 10. An output bearing assembly 25 includes a first bearing 26 and a second bearing 28. Both the bearings 26 and 28 include an inner race 30, an outer race 32, and a set of roller bearings 34 disposed between the inner race 30 and the outer race 32. Roller bearings 34 are preferably tapered roller bearings. A housing 38 having a shoulder 40 is integral with a wall 42 of the auxiliary section 14. The inner race 30 and the outer race 32 are press fitted into place on the output shaft 24 and against the housing 38 respectively. A bearing and seal retainer 46 is attached to housing 38 with a set of bolts 48. The retainer 46 supports a seal 44 for preventing oil leakage around the rotating yoke 18. The shoulder 40 in the housing 38 and a first side 50 of an output bearing cup spacer 52 position the outer race 32 of the first bearing 26. A second side 54 of the output bearing cup spacer 52 and the retainer 46 position the outer race 32 of the second bearing 28. Note, spacer 52 extends radially inwardly beyond a radially outermost extent of the outer faces of outer race 32. In a preferred embodiment the output bearing cup spacer 52 is made of powdered metal. The output shaft 24 has a shoulder 56 and the inner race 30 of the first bearing 26 is positioned between the shoulder 56 of the output shaft 24 and the speedometer rotor 22. The inner race 30 of the second bearing 28 is positioned between the speedometer rotor 22 and the yoke 18. A plurality of fins 58 project from the speedometer rotor 22. In the preferred embodiment there are sixteen fins 58 and the speedometer rotor 22 is made of powdered metal. The speedometer sensor 20 has external threads 60 adapted to be received in threads 62 in the housing 38. A hole 64 in the output bearing cup spacer 52 permits a first end 66 of the speedometer sensor 20 to extend through the housing 38 and the output bearing cup spacer 52 and to be at a predetermined depth in close proximity to the speedometer rotor 22. The top of the threads 62 in the housing 38 includes a straight thread O-ring port 67 as is well known in the art. A nut 68 is threaded onto the speedometer sensor 20 and holds a washer 70 against the output bearing cup spacer 52. An O-ring 71 is enclosed in the space defined by the washer 70, the straight thread O-ring port 67, and the speedometer sensor 20. The O-ring 71 seals the speedometer sensor 20 in the housing 38. In the preferred embodiment there are three speedometer sensors 20 mounted in the housing 38. The first end 66 of each speedometer sensor 20 is spaced radially outwardly of the speedometer rotor 22 and the output shaft 24. The sensors 20 may operate as is known in the art. It is the positioning of the sensors 20 which is inventive here. Figure 2 is a cross-sectional illustration taken along line 2-2 in Figure 1B. The housing 38 and the output bearing cup spacer 52 are disposed radially around the output shaft 24. The output bearing cup spacer 52 has a tab 72 which is received in a groove 73 in housing 38 to position spacer 52. The speedometer rotor 22 is mounted around the output shaft 24. In the most preferred embodiment there are three speedometer sensors 20 mounted in the housing 38. Figure 3 is a cross-sectional view of a preferred embodiment of the invention shown mounted on a half-view of the output shaft of the transmission. In this embodiment the output bearing cup spacer 52 is integral with the housing 38. Because the output bearing cup spacer 52 is integral with the housing 38, the shoulder 40 on the housing 38 is no longer necessary to position the outer race 32 of the first bearing 26. Instead, the design of the roller bearing 34 forces the outer race 32 of the first bearing 26 against the first side 50 of the output bearing cup spacer 52. The inner race 30 of the first bearing 26 is still positioned between the shoulder 56 of the output shaft 24 and the speedometer rotor 22. In all other respects, this embodiment is the same as that shown in Figure 1B. The transmission according to this invention offers the advantages of allowing the output bearings to be further spaced apart thereby reducing radial displacement of the output shaft of the vehicle. The transmission further provides for integration of the speedometer sensor and speedometer rotor into the output bearing assembly thus reducing the number of components in the transmission.

Claims: A transmission comprising: an output shaft (24) extending along a central axis; transmission sections (12, 14) for changing the speed of said output shaft (24); a pair of bearings (26, 28) mounted on said output shaft (24) beyond said transmission sections (12, 14); and at least one speedometer sensor (20) characterized in that the speedometer sensor (20) is mounted axially between said pair of bearings (26, 28). A transmission as recited in claim 1, wherein said speedometer sensor (20) is mounted within a spacer (52), said spacer (52) extending radially inwardly beyond a radially outermost extent of said pair of bearings (26, 28). A transmission as recited in claim 1 or 2, wherein the bearings (26,28) are part of an output bearing assembly for supporting said output shaft (24), said bearing assembly further including a housing (38), an output bearing cup spacer (52), and said at least one speedometer sensor (20) mounted within said housing (38), said housing (38) and said output bearing cup spacer (52) being spaced radially from said output shaft (24); a speedometer rotor (22) being provided which is mounted on said output shaft (24); said speedometer rotor (22) and said output bearing cup spacer (52) disposed axially between said pair of bearings (26,28); and said speedometer sensor (20) extending through said housing (38) and said output bearing cup spacer (52), with a first end (66) of said speedometer sensor (20) adjacent to said speedometer rotor (22) and between said pair of bearings (26, 28). A transmission as recited in claim 3, wherein a set of external threads (60) are formed on said speedometer sensor (20), a set of internal threads (62) are formed within a hole (64) in said housing (38), said speedometer sensor (20) threaded through said hole (64) in said housing (38), thereby mounting said speedometer sensor (20) within said housing (38). A transmission as recited in claim 4, wherein a washer (70) is positioned on said speedometer sensor (20) and held there by threading a nut (68) onto said speedometer sensor (20). A transmission as recited in any one of claims 3 to 5, wherein said output bearing cup spacer (52) is integral with said housing (38). A transmission as recited in any one of claims 3 to 6, wherein said housing (38) is integral with an auxiliary box housing. A transmission as recited in any one of claims 3 to 7, wherein one of said output bearing cup spacer (52) and said housing (38) having a tab (72) received in a groove (73) in the other of said housing (38) and said output bearing cup spacer (52) for positioning said output bearing cup spacer (52). A transmission as recited in any one of claims 3 to 8, wherein said speedometer rotor (22) is made of powdered metal. A transmission as recited in any one of claims 3 to 9, wherein said speedometer rotor (22) includes a plurality of fins (58). A transmission as recited in any one of claims 3 to 10, wherein said output bearing cup spacer (52) extending radially inwardly beyond a radially outermost surface of said bearings (26, 28). A transmission as recited in any one of claims 1 to 11, wherein said bearings (26, 28) are tapered roller bearings.

Inventors: ALLEN KEVIN MICHAEL, LOUZON THOMAS MARK, PELAEZ JOSE FELIPE, ALLEN, KEVIN MICHAEL, LOUZON, THOMAS MARK, PELAEZ, JOSE FELIPE, Peláez, José Felipe
Applicants: ZAHNRADFABRIK FRIEDRICHSHAFEN, ZF FRIEDRICHSHAFEN AG
Application year: 1998
Main classification: F16H59
IPC codes: F16H57, F16C41, F16H59, G01P3, F16C19