Hydraulic operating arrangement for clutches and the like

Abstract

The friction clutch between the prime mover and the change-speed transmission in the power train of a motor vehicle is actuatable by a slave cylinder cooperating with a master cylinder wherein the piston is movable by a clutch pedal or by an electric actuator. The casing of the slave cylinder is made, at least in part, of a plastic material and defines a plenum chamber arranged to receive pressurized fluid from the master cylinder by way of a conduit extending through a bell which contains the clutch and the slave cylinder. The annular piston of the slave cylinder surrounds the input shaft of the transmission. The plastic material of the casing of the slave cylinder can contain one or more additives which enhance its strength and/or influence its frictional engagement with the adjacent surfaces of the piston or of a lip seal which reciprocates with the piston. The piston and/or the lip seal can be installed in the casing to contact one or two metallic or plastic guide sleeves which are connected to or form part of the casing.

1 . A device for operating a clutch between a prime mover and a change-speed transmission in the power train of a motor vehicle, comprising: a casing including a portion confronting a part of a case of the transmission; and at least two substantially pin-shaped projections provided on said casing and received in complementary recesses provided in said part of the transmission case, said projections having deformable portions extending into the respective recesses and frictionally engaging said part of said transmission case.  
   
   
       2 . The device of  claim 1 , wherein said deformable portions extend radially beyond the respective projections and said openings are dimensioned to receive the respective projections with lateral play but to effect deformation of said deformable portions in response to insertion of the projections into the respective openings so that the deformable portions are self-lockingly retained in the respective openings.  
   
   
       3 . The device of  claim 2 , wherein the dimensions of said deformable portions decrease in directions as seen into the respective openings.  
   
   
       4 . The device of  claim 3 , wherein said deformable portions include elastic laminations.  
   
   
       5 . A hydraulically actuatable slave cylinder unit for operating a clutch between a prime mover and a change-speed transmission having a case and a rotary input shaft and forming part of a power train in a motor vehicle, comprising: a plastic casing; a guide sleeve provided in said casing and surrounding the input shaft of the transmission; an annular piston reciprocable in an annular chamber of said casing and surrounding said sleeve; a clutch operating release bearing provided in said chamber and affixed to said piston; and means for securing said sleeve to at least one of the transmission case and said casing, including a radially outwardly extending flange provided at one end of said sleeve and adjacent the transmission case, said flange having a radially outer portion received in a groove of said casing, and at least one retaining member provided in said casing and cooperating with said radially outer portion to hold said casing and said sleeve against axial movement relative to each other.  
   
   
       6 . The unit of  claim 5 , wherein said radially outer portion of said flange includes an annular array of extensions forming part of a bayonet mount of said at least one retaining member.  
   
   
       7 . The unit of  claim 5 , wherein said at least one retaining member is an integral part of said casing and is deformed to overlie said radially outer portion subsequent to insertion of said radially outer portion into said groove.  
   
   
       8 . The unit of  claim 6 , wherein said at least one retaining member is deformed as a result of a treatment involving at least one of hot caulking and ultrasonic caulking.  
   
   
       9 . The unit of  claim 5 , wherein said sleeve is received in said casing in stressed condition.  
   
   
       10 . The unit of  claim 9 , wherein said chamber is defined by said casing jointly with said sleeve.  
   
   
       11 . The unit of  claim 5 , further comprising at least one sealing element interposed between said casing and said sleeve.  
   
   
       12 . The unit of  claim 1   1 , wherein said at least one sealing element is selected from the group consisting of O-rings, flat seals, liquid seals and flow seals.  
   
   
       13 . The unit of  claim 12 , wherein said at least one sealing element includes a flow seal having a solidified flowable substance received in an annular second groove of said casing.  
   
   
       14 . The unit of  claim 13 , wherein said solidified flowable substance is selected from the group consisting of silicon rubber and silicon resin.  
   
   
       15 . The unit of  claim 13 , wherein said flow seal is disposed radially outwardly of said chamber and said casing has at least one inlet for admission of said flowable substance into said second groove.  
   
   
       16 . The unit of  claim 15 , wherein said second groove has a diameter slightly exceeding the diameter of said chamber.  
   
   
       17 . The unit of  claim 15 , wherein said at least one sealing element includes a flow seal having a ring-shaped sealing surface, said casing further having an axially raised sealing surface surrounding said inlet, engaged by said flow seal and in sealing engagement with said radially outer portion of said sleeve.  
   
   
       18 . The unit of  claim 5 , further comprising a stop for one of said release bearing and said piston, said stop being remote from said flange.  
   
   
       19 . The unit of  claim 18 , wherein said stop is of one piece with said sleeve.  
   
   
       20 . The unit of  claim 18 , wherein said stop is arranged to prevent disengagement of said piston and said bearing from said sleeve in storage and during transport of said casing.  
   
   
       21 . The unit of  claim 18 , wherein said stop constitutes a deformed portion of said sleeve.  
   
   
       22 . The unit of  claim 18 , wherein said stop includes at least one substantially radially outwardly extending tongue of said sleeve.  
   
   
       23 . The unit of  claim 18 , wherein said stop includes at least one tongue forming part of and extending at least substantially circumferentially of said sleeve.  
   
   
       24 . The unit of  claim 18 , wherein said guide sleeve consists at least in part of a plastic material and said stop is of one piece with at least one of said sleeve and said casing.  
   
   
       25 . A hydraulically operated disengaging system for a friction clutch in the power train of a motor vehicle wherein the clutch is installed between a prime mover and a change-speed transmission, comprising: a master cylinder unit; a slave cylinder unit including a casing and an annular piston reciprocable in an annular plenum chamber of said casing; means for conveying pressurized hydraulic fluid from said master cylinder unit into said plenum chamber; and an annular lip seal provided in said chamber and slidable relative to cylindrical internal and external surfaces provided within said casing radially outwardly and inwardly of said chamber, said casing including at least one cylindrical metallic sleeve and one of said surfaces being provided on said at least one sleeve.  
   
   
       26 . The system of  claim 25 , wherein said at least one sleeve is provided with said external surface.  
   
   
       27 . The system of  claim 25 , wherein said casing comprises two cylindrical metallic sleeves one of which is provided with said internal surface and the other of which is provided with said external surface.  
   
   
       28 . The system of  claim 25 , wherein said at least one sleeve consists, at least in part, of a material selected from the group consisting of aluminum, steel, titanium and the alloys thereof.  
   
   
       29 . The system of  claim 25 , wherein said at least one sleeve includes a film which is provided with said at least one surface and reduces the coefficient of friction between said at least one sleeve and said lip seal.  
   
   
       30 . The system of  claim 29 , wherein said film contains grease.  
   
   
       31 . The system of  claim 29 , wherein said film consists of a metal ennobling material.  
   
   
       32 . The system of  claim 25 , wherein said at least one sleeve has a substantially radially outwardly projecting extension, said lip seal being disposed in said chamber between said piston and said extension and said extension having a sealing surface abutting a plastic portion of said casing, and further comprising a second seal interposed between said plastic portion of said casing and said extension, a cover overlying said extension opposite said second seal and means for securing said cover to said plastic portion of said casing.  
   
   
       33 . The system of  claim 32 , wherein said means for securing said cover to said plastic portion of said casing includes an at least substantially annular joint selected from the group consisting of welded joints, adhesive joints and detents.  
   
   
       34 . A hydraulically operated disengaging system for a friction clutch in the power train of a motor vehicle wherein the clutch is installed between a prime mover and a change-speed transmission, comprising: a master cylinder unit; a slave cylinder unit including a casing and an annular piston reciprocable in an annular plenum chamber of said casing, said casing consisting at least in part of a plastic material; means for conveying pressurized hydraulic fluid from said master cylinder unit into said plenum chamber; and at least one sensor associated with said casing and arranged to monitor the positions of said piston in said chamber.  
   
   
       35 . The system of  claim 34 , wherein said at least one sensor is arranged to monitor distances covered by said piston in said chamber.  
   
   
       36 . The system of  claim 34 , wherein said at least one sensor is at least partially embedded in said casing.  
   
   
       37 . The system of  claim 36 , wherein casing is an injection molded article.  
   
   
       38 . The system of  claim 36 , wherein said means for conveying includes a tubular extension of said casing and further comprising conductor means embedded in said extension and connected with said at least one sensor.  
   
   
       39 . A hydraulically operated disengaging system for a friction cutch in the power train of a motor vehicle wherein the clutch is installed between a prime mover and a change-speed transmission, comprising: a master cylinder unit; a slave cylinder unit including a casing having an annular plenum chamber, an annular piston reciprocable in said chamber, a first cylindrical surface surrounding said chamber, a second cylindrical surface surrounded by said chamber, an annular lip seal disposed in said chamber, sealingly engaging said surfaces and reciprocable with said piston along and in sealing engagement with predetermined portions of said surfaces, and a metallic film provided at least on said predetermined portion of at least one of said surfaces; and means for conveying pressurized hydraulic fluid from said master cylinder into said plenum chamber.  
   
   
       40 . A hydraulically operated disengaging system for a friction clutch in the power train of a motor vehicle wherein the clutch is arranged to operate between a prime mover and a change-speed transmission, comprising: a master cylinder; a slave cylinder including a casing, a metallic sleeve received in said casing, defining with said casing an annular chamber and having limited freedom of radial movement relative to said chamber, an annular piston reciprocably received in said chamber, and an annular lip seal reciprocable in said chamber with said piston and having an internal surface sealingly engaging said sleeve and an external surface sealingly engaging said casing; and means for conveying pressurized hydraulic fluid from said master cylinder into said chamber.