Machine element or mechanism – Elements – Gear casings
Reexamination Certificate
2002-04-19
2003-12-02
Wright, Dirk (Department: 3681)
Machine element or mechanism
Elements
Gear casings
C474S028000
Reexamination Certificate
active
06655232
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a hydraulic controller used for a transmission which comprises an oil pump and a hydraulic control valve.
The present invention further relates to a hydraulic controller for a transmission which comprises an oil pump whose pumping action is generated by rotating an inner rotor (including an inner gear) that meshes with an outer rotor (including an outer gear), the inner rotor being positioned inside the internal circumference of the outer rotor. Such an oil pump can be, for example, a trochoidal pump or an internal gear pump.
BACKGROUND OF THE INVENTION
For hydraulically executing the shift control of a transmission, various types of hydraulic controller have been in use, and hydraulic controllers are incorporated in transmissions for hydraulic shift control. Such a hydraulic controller comprises an oil pump and hydraulic control valves, which are provided in the transmission housing. Various ways to incorporate such hydraulic elements in the transmission housing have been also known. For example, Japanese Laid-Open Patent Publication No. H03(1991)-121370 discloses a hydraulic controller in which hydraulic control valves are placed on the rear end of the transmission housing with a side cover covering these hydraulic control valves while an oil pump is placed at the front of the transmission housing.
In such a hydraulic controller, because the oil pump is positioned away from the hydraulic control valves in the transmission housing, it is necessary to form oil passages in the housing to supply oil from the oil pump to the hydraulic control valves. It is important to lay out the passages without complicating the arrangement. If the arrangement becomes complicated, then the length of oil passages tends to become longer. This problem can result in an increase in the flow resistance of oil passages, leading to an appreciable pressure loss, which reduces the efficiency of the pump.
There is an arrangement in which valve bodies constitute a pump casing wherein an outer rotor, an inner rotor, etc. are placed. However, the valve bodies are made of an aluminum material for weight saving while the oil pump is made of an iron material for strength. If valve bodies are to constitute a pump casing, then a question is what material it should be made of. For example, if valve bodies are made of an aluminum material, then the pump casing formed with these valve bodies may lack sufficient strength. In addition, if a rotor member made of an iron material is to be used in a pump casing made of an aluminum material, then the clearance between them in assembled condition must be larger than when both parts are made of an identical material. Without such a precaution, the pump will experience a reduction in volumetric efficiency. On the other hand, if the valve bodies are made of an iron material, then these problems will be solved, but this will contribute to the total weight of the transmission.
By the way, oil pumps of the type described above include, for example, trochoidal pumps and internal gear pumps. In such a pump, an inner rotor (including an inner gear) is positioned inside the internal circumference of an outer rotor (including an outer gear), and pumping action is generated by rotating the inner rotor, which meshes with the outer rotor.
Such an oil pump is mounted, for example, on an input shaft of a transmission and driven by the rotation of an engine to produce hydraulic pressure for shift control, etc. The pump as a unit does not have its own drive shaft because it is intended to be mounted on the input shaft of the transmission or a drive shaft which is connected directly with the output shaft of the engine. Therefore, the pump as a unit in preassembled condition has only an inner rotor and an outer rotor in a pump casing. The outer rotor is positioned (centered) and retained in the rotor-accommodating room of the pump casing while the inner rotor is placed, without any restriction, in the outer rotor.
When the pump is mounted on the drive shaft, the drive shaft fits into a bore provided through the inner rotor. As mentioned above, because the inner rotor is free in the outer rotor and not centered, it is difficult to insert and fit the drive shaft into the bore of the inner rotor in assembly process. To solve this problem, Japanese Utility-Model Publication No. 2589791 discloses an arrangement which makes the fitting of the drive shaft simple. In this arrangement, a taper is provided at an end face of the bore of the inner rotor (inner gear), and also a taper is provided at an end face of a cylindrical bush-like bearing, which is provided in the transmission housing to support the drive shaft, rotatably When the tapered part of the bearing is inserted into the tapered part of the bore of the inner rotor, the inner rotor is mounted and centered in the housing. In this condition, the drive shaft is fit into the bore of the inner rotor, which has been already centered in the housing.
However, this arrangement is disadvantageous because it limits the order of assembly for mounting the components of the pump in the transmission housing. In the order of assembly, the cylindrical bearing must be placed in the housing first, on which bearing, the inner rotor is mounted for centering. Also, this arrangement does not allow for the pump to be assembled independently as a unit. This is a problem because the components of the pump must be managed as independent parts in assembly processes until the final assembly of the pump to the transmission. Another problem is that as the pump is not assembled as a unit, the performance of the pump cannot be tested as a unit.
Japanese Laid-Open Utility-Model Publication No. S58(1983)-84387 discloses an arrangement for the centering of the inner rotor. In this arrangement, the inner rotor is provided with a cylindrical guide portion which protrudes from one end face thereof, and this guide portion is inserted into a guide-receiving bore formed in the casing. By this arrangement, the inner rotor of the pump can be centered as a unit, so the pump can be easily mounted on the drive shaft. However, in this case, as the inner rotor is provided with a cylindrical guide portion, not only the machining of the guide portion is an extra process, but also the grinding of the end face of the inner rotor is made difficult because of the existence of this guide portion.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a hydraulic controller which comprises an oil pump and hydraulic control valves placed next to one another in a compact manner.
It is another object of the present invention to provide a hydraulic controller which comprises a shift control valve whose valve body is made of an aluminum material and an oil pump made of an iron material.
It is yet another object of the present invention to provide a hydraulic controller which comprises an oil pump whose inner rotor is centered even while the pump exits as a preassembled unit. The present invention provides this centering without forming a protrusion like the above mentioned guide portion provided on an end face of the inner rotor.
A hydraulic controller according to the present invention comprises a valve body for a hydraulic control valve (for example, the valve body of the first hydraulic control valve
60
described in the following embodiment), an oil pump and a pump drive shaft (for example, the input shaft
1
of a transmission described in the embodiment). The valve body is mounted on an internal wall (for example, the end face S
1
of the first housing unit H
1
in the following embodiment) of a transmission housing (the first housing unit H
1
), the oil pump is mounted on the valve body, and the pump drive shaft is provided rotatably in the transmission housing. In this hydraulic controller, the oil pump comprises a pump casing, which is mounted to the valve body, an outer rotor and an inner rotor, both of which are provided in the pump casing. The pump drive shaft is inserted into the pump casing and fit into the in
Fujikawa Atsushi
Fujimoto Shuichi
Fukushima Yukihiko
Hasegawa Takashi
Ichijo Shuji
Honda Giken Kogyo Kabushiki Kaisha
Westerman Hattori Daniels & Adrian LLP
Wright Dirk
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