GB2089945A - Temperature-responsive viscous coupling - Google Patents

Abstract

A temperature-sensitive viscous coupling such as used for controlling the rotation of the cooling fan of an internal combustion engine has a valve 5', 8 controlling the flow of fluid between a torque transmitting chamber 4 and an oil reservoir 6, the valve being operated by a link rod 9 between the valve member 8 and a temperature sensitive element such as a bimetallic plate 10. The link rod passes through and is releasably secured to either the valve member 8 or the temperature-sensitive element 10, whereby the effective length of the link rod 9 can be adjusted and hence the operating temperature can be adjusted. This avoids the need to provide a stock of link rods having different lengths. <IMAGE>

Description

SPECIFICATION Temperature-sensitive fluid coupler BACKGROUND OF THE INVENTION Field of the Invention: The present invention relates to a temperaturesensitive fluid coupler for controlling the rotation of a cooling fan attached thereto to cool an internal combustion engine as on an automobile, and more particularly to such a temperaturesensitive fluid coupler including a link rod engaging between a temperature sensitive element such as a bimetal and a valve member for adjustable interlinkage therebetween.

Prior Art: Fluid couplers of the type described are widely used to eliminate a waste of power of the engine, and suppress fan noise or reduce fuel consumption. The fluid coupler includes a temperature-sensitive element or bimetal which begins to warp when the ambient air passing through the radiator reaches a certain temperature (from about 500C to 800C dependent on the car in which the fluid coupler is installed), thereby allowing a link rod to be lifted under the resiliency of a valve member mounted in an oil reservoir. The valve member as it is released by the link rod thus lifted opens a flow adjusting port in a partition on which the valve member is supported to permit oil to flow through the port into a torque transmitting chamber, thus causing a cooling fan attached to the fluid coupler to rotate at a higher speed.

As illustrated in FIG. 3 of the accompanying drawings, a conventional fluid coupler comprises a link rod 1 9 having ends in abutting engagement with a bimetal 20 attached to a bracket 21 mounted on a front face of a cover and a valve member 1 8 having one end riveted to a partition 1 7 to open and close a flow adjusting port 17' therein, for thereby allowing the bimetal 20 and the partition 1 7 to move in unison through the link rod 1 9. Varying axial dimensions of these components and their mutual dimensional differences on assembly, or their different resilient properties tend to fail to open and close flow adjusting ports 17' uniformly. For example, a difference of 0.1 mm in the length of rods 19 will be converted into a temperature difference of about 80C.It has therefore been necessary for manufacturers to carry an inventory of link rods with lengths varying by an increment of 0.03 mm and assemble fluid couplers with link rods selected through repeated product performance tests. Such an adjusting procedure is troublesome and time-consuming, and hence leads to a reduced rate of production.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a temperature-sensitive fluid coupler which will eliminate the prior difficulty.

Another object of the present invention is to provide a temperature-sensitive fluid coupler which is relatively simple in construction.

According to the present invention, a link rod acting between a temperature-sensitive element mounted on a front face of a cover and a valve member secured to a partition to open and close a flow adjusting port therein has one end threaded through either the temperature-sensitive element or the valve member.

The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which some preferred embodiments are shown by way of illustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a temperature-sensitive fluid coupler according to an embodiment of the present invention; FIG. 2 is a fragmentary cross-sectional view of a temperature-sensitive fluid coupler according to another embodiment; and FIG. 3 is a view similar to FIG. 2, showing a conventional temperature-sensftive fluid coupler.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a drive shaft 1 having a joint flange 1' for connection to an automotive engine, for example, supports through a ball bearing B a driven sealed housing which comprises a casing 2 and a casing cover 3 mounted thereon. The interior of the sealing housing is divided into an oil reservoir 6 and a torque transmitting chamber 4 by a partition 5 disposed in the casing cover 3 adjacent to an end of the drive shaft 1 remote from the foint flange 1', the partition 5 having an off-center flow adjusting port 5' therethrough. The drive shaft 1 fixedly supports on its end a drive disc 7 disposed in the torque transmitting chamber 4 with a small clearance 4' defined between the drive disc 7 and a confronting surface of the casing 2 for transmitting a torque from the drive dis 7 to the housing.

A resilient valve member 8 is mounted in the oil reservoir 6 and has one end riveted to the partition 4 and the other end located to open and close the flow adjusting port 5'. A temperature-sensitive element or bimetal 10 in the form of a plate is secured at opposite ends to a bracket 11 fixed to a front face of the casing cover 3. A link road 9 extends axially through the casing cover 3 and has one end held in abutment with the bimetal 10 and the other end threaded at 14 through the valve member 8. Therefore, the link road 9 permits the bimetal 10 and the valve member 8 to move axially in unison. The housing has therein a dam 1 2 disposed at a region where oil will be collected under centrifugal forces generated when the drive disc 7 is rotated.The oil as collected will be pumped by the dam 12 through a circulation passage 1 3 extending in communication with the torque transmitting chamber 4 and the oil reservoir 6. The casing 2 has a plurality of threaded holes 1 5 receptive of screws to attach fan blades (not shown) to the casing 2.

According to another embodiment shown in FIG. 2, one end of the rod 9 is threaded at 14 through the bimetal 10 with the other end held in abutting engagement with the valve member 8.

The threaded end of the link rod 9 and the interengaging threaded part of the bimetal 10 or the valve member 8 are fastened together by an adhesive for instantaneous bonding after the link rod 9 has been adjusted for the actuation of the valve member 8 at a desired ambient temperature.

During an adjusting operation, the link rod 9 is rotated about its own axis to adjust its axial dimension between the bimetal 10 and the valve member 8 until the valve member 8 is about to open the flow adjusting port 5' under its own resiliency while the bimetal 10 is maintained at a desired ambient temperature selected for the operation of the valve member 8. Accordingly, it is not necessary to keep a variety of link rods of different lengths to choose from, and to repeat performance tests on link rods before a desired link rod is picked out. Only a sinqle link rod suffices for each fluid coupler during adjustment.

Fluid couplers of the present invention can be assembled in a shorter period of time than prior fluid couplers, and are of uniform operation characteristics.

Although certain preferred embodiments have been shown and described in detail, it should be understood that many changes and modifications may be made therein without departing from the scope of the appended claims.

Claims (5)

1. A temperature-sensitive fluid coupler comprising: a torque transmitting chamber, and an oil reservoir; a valve member for opening and closing a flow adjusting port communicating between an oil reservoir and a torque transmitting chamber and movable by a link rod in response to a temperature sensitive actuator or element, wherein one end of the link rod passes through and is releasably secured to one of said valve member and said temperature-sensitive element and the other end held in abutment with the other of said valve member and said temperaturesensitive element for adjusting the effective length of the link rod.

2. A fluid coupler according to claim 1, wherein the said one end of the link rod is threaded through the valve member or the temperaturesensitive element.

3. A temperature-sensitive fluid coupler comprising: a housing including a casing, a casing cover mounted thereon, and a partition secured to said casing cover, said casing and said partition jointly defining a torque transmitting chamber, said casing cover and said partition jointly defining an oil reservoir; a drive disc disposed in said torque transmitting chamber with a small clearance between the drive disc and a surface of said casing which defines said torque transmitting chamber, a flow adjusting port defined through said partition for providing communication between said oil reservoir and said torque transmitting chamber; a valve member mounted on said partition for opening and closing said flow adjusting port; a temperature-sensitive element mounted on said casing cover; and a link rod having one end threaded through one of said valve member and said temperature-sensitive element and the other end held in abutment with the other of said valve member and said temperaturesensitive element for adjustable interlinkage therebetween.

4. A fluid coupler according to any one of claims 1 to 3, wherein the temperature-sensitive element comprises a bimetallic plate.

5. A fluid coupler according to any one of claims 1 to 4, comprising a dam disposed in the torque transmitting chamber and a circulation passage communicating between the oil reservoir and the torque transmitting chamber for delivering oil from the torque transmitting chamber to said oil reservoir 6; A temperature-sensitive fluid coupler constructed and arranged substantially as hereinbefore described and as illustrated in Figures 1 and 2 of the accompanying drawings.