Patent Application
20060060444
This invention relates to torque-transmitting mechanisms and, more particularly, to electromechanical apply systems for torque-transmitting mechanisms.
Automotive automatically shifted transmissions generally require a plurality of torque-transmitting mechanisms that are selectively operable to effect interchange between transmission ratios as well as maintaining the transmission ratio. The torque-transmitting mechanisms are either rotating type, commonly termed clutches, or stationary type, commonly termed brakes. These devices are hydraulically applied to an axially movable piston. The hydraulic pressure, which is utilized to apply the torque-transmitting mechanism, is supplied through an electro-hydraulic control mechanism, which includes a plurality of valve members as well as a plurality of pressure control members. This requires a large amount of fluid to be moved at high pressures through fairly narrow and constricted or tortuous paths.
The complexity of the hydraulic system requires a significant expenditure of capital to ensure that the transmission control system operates properly over a long period of time. One of the more important aspects of this control system and the efficiency thereof is the sealing of the hydraulic fluid to reduce the amount of leakage, which might otherwise occur within the system.
It is an object of the present invention to provide electro-mechanically applied torque-transmitting mechanisms for use in a planetary type multi-speed automatic shifting power transmission.
In one aspect of the present invention, a spiral spring and a torque-transmitting apply member are operatively connected to provide linear motion of the apply member during the engagement of a torque-transmitting mechanism.
In another aspect of the present invention, at least one portion of the apply mechanism is rotated by an electric motor which results in the axial progression of the apply piston toward the engagement condition of the torque-transmitting mechanism.
In yet another aspect of the present invention, the rotating apply mechanism is operatively connected with the spiral spring which is interwoven with the apply piston such that rotation of the spiral spring results in linear translation of the apply piston.
In yet still another aspect of the present invention, a plurality of rollers are disposed in a housing between adjacent coils of the spiral spring and the housing is rotated by a rotating mechanism to enforce linear motion of the spiral spring and the apply piston of the torque-transmitting mechanism.
With the present invention, the torque-transmitting mechanisms are mechanically applied through the linear actuation of an apply piston and the linear motion of a spiral spring. The apply mechanism consists of an electric motor and therefore does not have a need for high-pressure fluid to actuate the apply piston. The fluid system of the transmission therefore only needs to supply lubrication and cooling flow to the various components of the transmission such as the friction plates, gear mechanisms, and bearings. This greatly reduces the assembly and manufacturing costs of the transmission.
Referring to the drawings, wherein like characters represent the same or corresponding parts throughout the several views, there is seen in
The sun gear member 22 is drivingly connected with a shaft 28, which might represent the input shaft to a transmission. The ring gear member 24 is connected with a hub 30, which might be connected to a torque-transmitting mechanism, not shown. The ring gear member 18 and planet carrier assembly member 26 are interconnected through a hub portion 32. The planet carrier assembly member 20 is connected with a hub 34, which might be connected also to a torque-transmitting mechanism, not shown. The planet carrier assembly member 20 is also connected with a transmission output shaft 36. The sun gear member 16 is operatively connected with a stationary torque-transmitting mechanism 38.
As best seen in
A spiral spring 54 is secured to the gear housing 46 and rotates therewith. An apply piston 56 has an outer circumferential portion 58, which is splined to a transmission housing 60. The piston 56 also has a central radially extending portion 62 and an inner circumferential and axially extending portion 64. The radial portion 62 passes between adjacent coils of the spiral spring 54. The inner axial portion 64 is disposed to abut a pressure plate or friction plate 66.
The torque transmitting mechanism 38 also includes a pressure plate 66 a plurality of friction plates 68 and a backing plate 70 all of which are splined to the housing 60. The pressure plate 66, friction plates 68, and backing plate 70 are alternately spaced with a plurality of friction plates 72, which are splined to a hub 74. The hub 74 is drivingly connected with the sun gear member 16. As is well known, with torque-transmitting mechanisms, one of the sets of friction plates, for example 72, are lined with a friction material, while the other plates 66, 68, and 70 are plain steel plates. The plates 66, 68, 70 and the plates 72 combine to form a “clutch pack” or “friction pack” that is a conventional structure well known in the art.
The electric motor 52 is controlled by a conventional electronic control system, which may include a preprogrammed digital computer, not shown. When it is desired to operate the torque-transmitting mechanism 38, the electric motor 52 is rotated thereby causing rotation of the gear housing 46. The gear housing 46 is supported on a bushing 76, and supported in a thrust direction by a thrust needle bearing 78.
As the gear housing 46 rotates, the spiral spring 54 will also rotate, such that the apply piston 56 will be moved axially between adjacent coils of the spiral spring resulting in enforcement of frictional engagement between the plates 66, 68, 70, and the friction plates 72. To enforce disengagement of the torque-transmitting mechanism 38, the electric motor 52 is rotated in the opposite direction thereby causing the apply piston 56 to translate rightward, as seen in
In
The torque-transmitting mechanism 100 depicts only three friction plates for simplicity of description; however, a plurality of plates might be splined to the housing 102 and a like number of plates 110 would be splined to the housing 104. Both of the housings 102 and 104 are permitted to rotate such that the torque-transmitting mechanism 100 is a rotating-type torque-transmitting mechanism, commonly termed a clutch.
Further components of the torque-transmitting mechanism 100 include an apply piston 112, which is separated from the plate 108 by a roller thrust bearing 114. The apply piston 112 is splined to a stationary housing 116, which also supports an electric motor 118.
A spiral spring 120 is drivingly connected to a tab 122 on the apply piston 112. Thus, the end of the spring 120 is stationary relative to the piston 112. A plurality of rollers 124, as best seen in
The housing 126 is supported on a pair of bushings 132 and is also supported by a roller thrust bearing 134. Thus, the housing 126 is rotatably supported on and rotates relative to the housing 116. As the rollers 124 are driven in a rotational sense, as best seen in
If the spiral spring 120 advances in the direction of Arrow A, the apply piston 112 will advance in the direction of Arrow C, as shown in
From the above teaching, those skilled in the art will recognize that the mechanism is employable in two systems. A motor drives the spiral spring with the rotation of the spring causing it to thread between stationary pins to move spring material to one side of the pins. The spiral spring pushes against the clutch plates. The motor drives the housing with pins and the spring is retained from rotating causing the spring to thread through the pins and drive the pins forward or backward. The housing presses against the clutch plates.
