GB2097873A

GB2097873A - Cooling mechanism for a clutch

Info

Publication number: GB2097873A
Application number: GB8210370A
Authority: GB
Original assignee: Daikin Manufacturing Co Ltd
Current assignee: Exedy Corp
Priority date: 1981-04-30
Filing date: 1982-04-07
Publication date: 1982-11-10
Also published as: DE3215999A1; GB2097873B; JPS57175821U

Abstract

Clutch retainer sleeve 4 surrounds with a clearance, part of output shaft 6 of clutch C; it projects at one end to within cover 13 of the clutch C and at the other end, outside the clutch C, connects with an air intake pipe 18. Release bearing 11 carried on sleeve 10 slidable on the retainer 4 cooperates with diaphragm spring 12 or one or more release levers (not shown), by which the clutch C is actuated. Radial air exit holes 21 are provided peripherally in clutch cover 13 and in register with these holes 21 is a heated air exhaust hole 22 which is connected to the air inlet 25 or exhaust outlet 26 of engine 2 whereby cooling air, drawn from the atmosphere is positively aspirated through the clutch C. <IMAGE>

Description

SPECIFICATION Cooling mechanism for a clutch The present invention relates to a clutch having a cooling mechanism, and which preferably include a diaphragm spring.

A main object of the invention is to provide an arrangement whereby unheated cooling air from the outside of the clutch housing is introduced directly into a central portion of clutch where frictional heat arises and would otherwise build up around friction facings of the clutch. Another object of the invention is to provide an arrangement which serves to exhaust the heated air from inside of the clutch positively.

In conventional agricultural tractors or industrial vehicles, the clutch housings are generally tightly closed. In the prior art, the internal clutch temperatures often rise as high as 200 to 3500C as a result of the repeated operations of engaging and disengaging the clutch, and these high temperatures can often cause fatigue of the sealing arrangements and/or decrease the useful clutch life.

To cope with the problem, an improved ventilation mechanism has been proposed in which an air inlet, with an air cleaner, is installed on the upper portion of a clutch housing, an air exhaust is provided at the bottom of the clutch housing, and this air exhaust is connected to an outlet portion of an exhaust gas muffler, whereby suction, induced by the exhaust gas, causes ventilation of the inside of the clutch housing. In the prior proposal, since cold outside air is not positively introduced into the clutch housing, the cooling for the friction facings of the clutch is not sufficient.

In another prior known type of clutch, in which coil springs are used for clutch springs, a construction has been proposed in which a ventilation pipe extends tightly through a hole drilled vertically through the upper wall of a housing of the clutch, the lower open end of the ventilation pipe is disposed close to the upper portion of a release bearing support retainer inside the clutch housing, and air impeller blades are fixed on the side wall surface of a clutch cover which surrounds the release bearing. In this arrangement, complicated air impeller blades are necessary on the clutch cover side face. Rotary friction of the apparatus increases the power necessary to drive the apparatus, and manufacturing costs of the arrangement are high.

In addition to these disadvantages, the ventilation pipe is susceptible to being broken, because only its upper part is supported by the clutch housing and its lower part is free to vibrate. Although there is an annular clearance between the clutch cover and the release bearing, and the clutch cover incorporates air impeller blades which stimulate air suction inside the clutch housing, hot air exhausted from inside the clutch assembly and filled to the clutch housing is apt to be reintroduced repeatedly into the clutch in company with cold outside air which is supplementarily introduced through the ventilation pipe, so that cooling efficiency is not so high as it should be.

The present invention has for its object to provide an arrangement which ensures that only cold air from outside the clutch housing is introduced positively and directly into the clutch assembly which is covered by a diaphragm spring or release levers, through an annular clearance between a fixed sleeve retainer pipe of the clutch and an output shaft of the clutch which shaft extends through the sleeve retainer pipe.

With this object in view, the present invention provides a clutch comprising an output shaft extending through a tubular sleeve retainer with an annular clearance around the shaft, the sleeve retainer being disposed inside a clutch housing, a release bearing facing the central periphery of a diaphragm spring or the centrally-disposed end portion(s) of one or more release levers, said release bearings being located on a sleeve slidable on the sleeve retainer; characterised in that to provide a cooling mechanism for the clutch, one end of the sleeve retainer opens inside the clutch and the other end of the sleeve retainer, outside the clutch, is connected to atmosphere outside a housing of the clutch through an air intake pipe, heated air exit holes or recesses being provided in a peripheral portion of the clutch, and a heated air exhaust hole aligned with the heated air exit holes being connected to a vacuum port of an engine so that hot air from the clutch is positively aspirated into the engine.

Other and further objects, features and advantages of the invention will appear more fully from the following description of a preferred embodiment of the invention as illustrated in the accompanying drawings in which the single figure is a diagrammatic longitudinal sectional view illustrating a preferred embodiment of the clutch of the invention.

The illustrated embodiment of the clutch of the invention comprises a clutch housing 1 mounted at its front end (the left end in the drawing) onto a cylinder block of an engine 2 and at its rear end onto a transmission 3. In the centre of the clutch housing 1 there is a horizontal tubular sleeve-like retainer 4 which is fixed in place by a plurality of bolts (not shown). An output shaft 6 extends through the retainer 4 with an annular clearance 5 therebetween. The front end of the output shaft 6 is supported in the central part of flywheel 8 by means of a bearing 7, and the middle portion of the output shaft 6 is supported in the casing of the transmission 3 by means of a bearing 9.

On the outer surface of the sleeve retainer 4 a sleeve 10 is slidably disposed, and a release bearing 11, mounted on the front end of the sleeve 10, faces against the inner side surface of diaphragm spring 12 with a small clearance. The sleeve 10 engages with a shift fork (not shown) whereby rotation of the sleeve 1 O is prevented.

A clutch cover 13, which supports the diaphragm spring 12, is fixed to the flywheel 8 by way of a plurality of bolts. Between the flywheel 8 and a pressure plate 14 which is supported from the clutch cover 1 3 by straps (not shown) extending tangentially of the clutch cover, are friction facings 1 6 which are apertured and which are attached to the outer periphery of a clutch disc 1 5. The clutch disc 1 5 is splined on the output shaft 6 so as to be slidable thereon.

The front end of the sleeve retainer 4 opens in front of the diaphragm spring 1 2 inside the interior space 1 7 of the clutch, and in the clearance 5 behind the sleeve 10, the lower end of an air inlet pipe 1 8 is connected thereto in air tight condition, which inlet pipe 1 8 extends upwards, through a hole 19 in the upper part of the clutch housing 1 in a similar air tight manner. The upper end of the pipe 1 8 opens to the outside atmosphere by way of a filter 20. Heated air emission or exit holes or recesses 21 are formed in the outer periphery of the clutch assembly.The outer periphery of the clutch housing 1 facing or registering with the heated air exit holes or recesses 21 is provided with a heated air exhaust hole 22 which is connected to an air intake pipe 25 of an air cleaner 24 by way of a pipe 23. Instead of or in addition to connecting the pipe 23 to the air intake pipe 25, the pipe 23 may be connected to a common exit pipe 26 of an exhaust manifold 27.

When the engine 2 is running, air in the central portion of the clutch C (i.e. central part of the space 17) is forcibly evacuated by centrifugal force thereby causing a low interior pressure.

Because of this low pressure, cold air from outside the clutch housing 1 is positively introduced into the interior space 1 7 through the filter 20, the air intake pipe 18, and the clearance 5, and some part of this introduced air flows radially outwardly toward the heated air emit hole 21, while the clutch is engaged through passages formed between grooves present on the friction facing 1 6 and the flywheel 8, and on the friction facing 1 6 and pressure plate 14.The rest of the introduced air flows toward the heated air exit hole or recess 21, through the clearance between the pressure plate 14 and clutch cover 13, where the air passes and becomes heated, and flows rapidly from the heated air exit hole 21 toward radially outwardly, thereby causing a sharp increase of pressure inside vacant space 16' in the clutch housing 1.

On the other hand, since a low pressure inside in the air intake pipe 25 is transmitted to the opening of heated air exhaust hole 22, heated air arising around the clutch periphery is compulsorily sucked into the engine 2 through the hole 22, the pipe 23, the air intake pipe 25 and air cleaner 24. In the case where the pipe 23 is connected to by way of a common exit manifold 26 to the exhaust, a vacuum is produced inside the pipe 23 by reason of exhaust gases passing rapidly through the common exit manifold 26, which vacuum actively evacuates, from the clutch, the hot air surrounding the clutch assembly.

As stated hereinbefore, although the interior clutch space 1 7 and interior space 16, with the housing are substantially separated or isolated by the release bearing 11 and the rotating diaphragm spring 12, only cold outside air alone is induced directly into the central portion of the interior of the clutch inside space 1 7. One end of the space or clearance 5 formed between the sleeve retainer 4 and the output shaft 6 opens wide in the interior clutch space 17, and the other end part of the clearance 5, outside the clutch assembly proper, is directly connected to the atmosphere outside the clutch housing 1. As a result, the friction facings 1 6 which are likeiy to overheat, and parts surrounding the friction facing 1 6 are efficiently cooled.As a result, the frictional characteristic of the friction facing 16 is maintained in a stable condition, thereby causing stable transmission of torque by the clutch. In addition to the above advantages, the diaphragm spring 12 and its supporting members are maintained at a low temperature and therefore they are guarded against the effect of heat. Wear of the friction facing 1 6 is decreased and long clutch life is obtained. The air intake pipe 18, as well as its supporting members will not become broken even when subjected to severe vibrations, e.g. in the running operation of the machine, in that the lower end of the air intake pipe 1 8 is supported by the sleeve retainer 4, and upper end portion of the pipe 18 is supported by the clutch housing 1, thereby assuring its long life.If the heated air exhaust pipe 23 is connected to the air intake pipe 25, asbestine wear powder (which is produced from the friction facing 16) is prevented from spreading into the atmosphere thereby minimising air pollution. Heated air introduced into the engine 2 promotes and/or improves fuel combustion by the engine. If the pipe 23 is connected to the exhaust manifold common exit pipe 26, the heated air also ensures burning or oxidation of unburned components contained in the exhaust gas so that air pollution is effectively prevented.

The present invention is also applicable to different type of clutches, in which coil springs and release levers are used instead of the diaphragm spring.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form may be changed in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as defined by the following claims.

Claims

1. A clutch comprising an output shaft extending through a tubular sleeve retainer with an annular clearance around the shaft, the sleeve retainer being disposed inside a clutch housing, a release bearing facing the central periphery of a diaphragm spring or the centrally-disposed end portion(s) of one or more release levers, said release bearing being located on a sleeve slidable on the sleeve retainer; characterised in that, to provide a cooling mechanism for the clutch, one end of the sleeve retainer opens inside the clutch, and the other end of the sleeve retainer, outside the clutch, is connected to atmosphere outside a housing of the clutch through an air intake pipe, heated air exit holes or recesses being provided in a peripheral portion of the clutch, and a heated air exhaust hole aligned with the heated air exit holes being connected to a vacuum port of an engine so that hot air from the clutch is positively aspirated into the engine.

2. A clutch as claimed in claim 1 wherein the vacuum port is formed in an air intake passage of the engine.

3. A clutch as claimed in claim 1 wherein the vacuum port is formed in an exhaust gas passage of the engine.

4. A clutch as claimed in claim 1,2 or 3 wherein one end of the air intake pipe is supported by the sleeve retainer and the other end thereof is supported by the housing of the clutch.

5. A clutch substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.