Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on... – Fluid pressure actuator for adjustment of member
Reexamination Certificate
2001-05-14
2003-09-30
Hannon, Thomas R. (Department: 3082)
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
Fluid pressure actuator for adjustment of member
C474S018000
Reexamination Certificate
active
06626779
ABSTRACT:
RELATED APPLICATIONS
This application claims the priority of Japanese Patent Application No.2000-204309 filed on Jul. 5, 2000, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a continuously variable transmission oil pressure control device and, more particularly, to an oil pressure control device in which the operating characteristic of a valve that is arranged in the continuously variable transmission is improved.
2. Description of the Related Art
Continuously variable transmissions comprising: a drive pulley and a driven pulley freely rotatably journalled within a transmission housing; a belt that transmits rotary force arranged between these pulleys; and an oil pressure actuator used to vary the width of the pulley groove of the drive pulley and driven pulley by moving moveable pulley halves of the drive pulley and driven pulley in the respective pulley axial directions and which is used to change the reduction ratio between the drive pulley side rotary shaft and driven pulley side rotary shaft in continuously variable fashion are employed for example as transmissions for vehicles.
In a continuously variable transmission for a vehicle, a plurality of oil pressure control valves such as a pulley control valve for controlling the groove width of the drive pulley and driven pulley by controlling lateral pressure acting on the moveable pulley half and/or a clutch control valve that effects engagement control of the clutch used in the transmission are employed; these oil pressure control valves are accommodated in the same housing as the continuously variable transmission mechanism comprising the drive pulley and driven pulley, etc., in order to achieve a compact construction of the transmission as a whole. Due to restrictions regarding arrangement space, etc., in some cases the drain ports of such oil pressure control valves are arranged on the line of extension of the circumference of the rotating pulley or the line of extension of the circumference of the rotating belt.
In order to suppress generation of heat resulting from friction between the drive pulley or driven pulley and the belt in the continuously variable transmission mechanism, transmission oil is supplied that lubricates these structural members; this transmission oil used for lubrication/cooling flies off in the circumferential direction of the rotary bodies constituted by the pulleys or the belts and collides with the inside wall of the transmission housing or oil pressure control valves, etc., which are on the line of extension of this circumferential direction. Consequently, if the aperture of the drain port in the oil pressure control valve was in a region on the line of extension of the circumferential direction referred to above, there was the problem that it could easily be affected by splashes of transmission oil flung out from the continuously variable transmission mechanism (the kinetic energy (dynamic pressure) possessed by the splashes acting for example as a back pressure causing fluctuation of the valve).
Construction of an oil pressure control device has been considered in which the valve body in the oil pressure control valve is arranged immersed in transmission oil within an oil pan, the aperture of the drain port in this oil pressure control valve being arranged in an in-oil region. With such a construction, the above problem can be alleviated. However, if the aperture of the drain port was arranged in an in-oil region, when, for example, the ambient temperature was low and the oil viscosity in the oil pan was therefore high, the oil present around the drain port aperture presented resistance to discharge, adversely affecting the response of the oil pressure control valve and leading to problems such as variability of the control characteristic of the controlled member (for example the clutch or drive/driven pulley) with oil temperature, or large moving-off shock when the vehicle moved off. Also, even if the drain port aperture was arranged in an in-oil region, the situation could arise in which the drain port was exposed to splashes by being exposed above the oil surface on shaking of the vehicle, driving while climbing or descending a slope, vehicle acceleration/deceleration, or when the oil surface fell with the viscosity being raised by low oil temperature, etc.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a continuously variable transmission oil pressure control device wherein there is no possibility of this being affected by splashes of transmission oil flung out from the continuously variable transmission mechanism, even under such vehicle conditions.
The present invention comprises: a continuously variable transmission comprising: a drive pulley and driven pulley freely rotatably journalled in a housing and respectively having a pair of a fixed pulley half and moveable pulley half, a belt arranged between the drive pulley and driven pulley and that transmits rotational force between the drive pulley and driven pulley; an oil pressure actuator that varies the width of the pulley groove of the drive pulley and the driven pulley by moving the respective moveable pulley halves in the drive pulley and driven pulley in the respective pulley axis directions; wherein, in this continuously variable transmission, there is provided an oil pressure control valve having a drain port that opens in the interior of the housing. In addition, according to the present invention, an oil pressure control device of a continuously variable transmission is constituted wherein the apertures of the drain ports in an oil pressure control valve are arranged outside of the maximum range of movement (for example, belt range) defined by extension in the circumferential direction of the belt of the maximum width, for example the maximum width of the range of movement through which the belt can move in the pulley axis direction, of the range of movement when the pulley groove width of the drive pulley and driven pulley is changed by moving the moveable pulley halves of the drive pulley and driven pulley, and towards the outside of the belt region.
As is well known, the gear-change action in a continuously variable transmission as described above is performed by varying the radius with which the belt is wound on the respective pulleys by changing the width of the pulley grooves (V groove width: separation between the V face of the fixed pulley half and the V face of the movable pulley half of both the drive pulley and driven pulley, which have respectively tapered V-groove faces. The positional relationship of the moveable pulley halves in the drive pulley and driven pulley is usually such that the respective V faces are arranged so as to be opposite on the two pulley shafts which are arranged parallel to each other, so that, when gear-change operation is effected, the belt is moved parallel with the pulley axis direction.
In the above construction according to the present invention, the aperture of the drain port in the oil pressure control valve is arranged outside of the belt region defined by extending the maximum width of the range of movement in which the belt can be moved in the pulley axis direction in the circumferential direction of the belt. The maximum width of the range of movement in which the belt can be moved in the pulley axis direction means the maximum width of the positions which the two ends of the belt can take when a belt having a fixed width in the pulley axis direction is moved in the pulley axis direction by the gear-change operation, and the belt region defined by extending this maximum width in the circumferential direction of the belt means the region in which direct collision with oil splashes flung off by centrifugal force from the rotating belt is possible.
Consequently, with a construction according to the present invention in which the aperture of the drain port in the oil pressure control valve is arranged outside this belt region, an oil pressure control device of a continuou
Kanda Masahiro
Ohyama Eiji
Tsubata Yoshimichi
Armstrong Westerman & Hattori, LLP
Hannon Thomas R.
Honda Giken Kogyo Kabushiki Kaisha
Johnson Vicky A.
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