JPS58106230A - Fluid clutch, temperature thereof is controlled - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature-controlled fluid clutch, for example for a fan of an internal combustion engine.

A temperature-controlled hydraulic clutch or hydraulic friction clutch for a fan of an internal combustion engine is known from German Patent Application No. 2814608.

A fluid clutch has a substantially disk-shaped rotor that is rotationally driven by an internal combustion engine, and a casing that surrounds the rotor and rotates relative to the rotor, and the casing supports the blades of a fan. ing.

The axial surface of the rotor, together with the adjacent surface of the casing working chamber surrounding the rotor, forms a substantially radially extending shear gap, which shear gap is filled with a shear fluid in operating conditions. The shear fluid transmits drive torque from the rotor to the casing. The shear fluid is a highly viscous liquid. Adjacent to the working chamber in the axial direction, a reservoir for fluid is provided in the housing, which reservoir is connected to the shear gap via a suction opening. The shear fluid enters the working chamber from the storage chamber via the suction opening. In the radially outer region of the shear gap, a pump device, for example formed by a displacement member, is provided, which pump device returns the shear fluid from the working chamber to the storage chamber. The suction opening has a temperature-controlled shut-off valve, which is opened when the temperature rises and closed when the temperature falls, for example by means of a two-metal strip. When the isolation valve is closed, the pump device pumps shear fluid out of the work chamber, thereby disengaging the fluid clutch and switching on the fan.

The torque transmitted by the shear fluid is related to the width of the shear gap. The larger the width, the smaller the transmitted torque under otherwise equal conditions. In order to obtain limited operating conditions of the fluid clutch, the width of the shear gap must be maintained relatively precisely. Such a requirement is subject to negligible manufacturing tolerances, but this increases the manufacturing cost of the fluid clutch. In the case of the above-mentioned known hydraulic clutches, the rotor is formed as an axially flexible disk, which disk is brought to the center of the working chamber by the pressure of the shearing fluid and is separated by a gap of approximately the same width. is taken into consideration.

In the case of known hydraulic clutches, a compromise has to be made between the degree of deflection of the rotor and the transmitted torque. Since the shear gap in the case of known hydraulic clutches has a constant width in the radial direction, the shear fluid is loaded with varying strengths in relation to the radius. The stress in the shear vehicle and therefore in the shear fluid is proportional to the local velocity difference between the casing and rotor and inversely proportional to the width of the shear gap at the point where the velocity difference occurs. As the radius increases, the differential velocity increases, so that for shear gaps of exactly the same width, the stress in the shear fluid increases radially outward. In the radially outer region of the shear gap, unacceptably high stresses and unacceptably high warm blood of the shear fluid occur, and these stresses and temperatures can inhibit torque transmission in the short term. In the long term, the shear fluid is destroyed.

Furthermore, the pumping device arranged in the radially outer extent of the shear gap does not allow the shear gap to be completely emptied due to the force exerted on the fluid by the centrifugal force of the shear fluid in the storage chamber, so that the shear gap cannot be completely emptied. % IJ song state is inconvenient. Known fluid clutches have a relatively high residual torque.

Another difficulty with known fluid clutches is that the fully filled shear gap can only be emptied relatively slowly after the closure of the isolation valve. In addition, the pumping action of the pump device is likewise small due to the relatively small rotational speed difference between the pump and the housing. This causes the shear gap to empty with a delay. Since the first radially inner region of the shear gap that is emptied contributes only a small amount to the transmitted torque in the case of conventional fluid clutches, the transmitted torque is initially reduced only slightly.

The object of the present invention is to eliminate the disadvantages of conventional hydraulic clutches, to be simple in construction and at the same time load the shear fluid uniformly, to shorten the delay in disconnection, and to reduce the transmission torque (idling torque) in the disconnected state. ) is reduced, and the other is to provide a fluid clutch for the internal combustion engine fan.

In order to solve these problems, (a) two clutch parts that are rotatable relative to each other around a common rotational axis; and ←) a first clutch part that surrounds the second clutch part. (c) at least one shear gap extending at different radii and/or a plurality of shear gaps extending at different radii between mutually adjacent surfaces of the working chamber and the second clutch portion; , in) The first
a storage chamber for shear fluid located within the clutch portion of the;

(e) at least one suction opening for shear fluid leading from the storage chamber to the shear gap or gaps; in particular for a fan of an internal combustion engine, having a pumping device on the outside and (g) a temperature-related controlled valve for controlling the shear flow wake through the suction opening or the pumping device. Starting from a temperature-controlled hydraulic clutch, the invention provides that the width of the shear gap(s) is designed in relation to the radial spacing between the shear gap(s) and the axis of rotation; It is characterized in that the width increases as the distance increases. Owing to the shear gap width increasing with increasing distance from the axis of rotation, a uniform differential velocity within the shear gap is obtained, which results in a uniform shear stress of the shear fluid.

Furthermore, the radially inner shear gap or the shear gap width can make a significant contribution for the transmitted torque, so that the pumping action upon disengagement of the fluid clutch can be initiated quickly.

Rapidly initiated pumping action is particularly important for cold start conditions of fluid clutches for cooling fans. In the case of cold-start internal combustion engines, the shear gap is significantly filled with shear fluid due to the preceding stoppage time, and therefore the engine. must be emptied as quickly as possible to avoid further cooling.

In addition to fluid-specific values, such as the viscosity of the shear fluid, the locally transmitted special torque is related to the fourth power of the radius and inversely proportional to the local shear gap width. The gap width is increased in the radially outer region of the shear gap, which reduces the residual torque transmitted by the disconnected hydraulic clutch (and thus the eye of the hydraulic clutch).
The engine speed is reduced by +11. The uniform shear stress of the shear fluid in the shear gap avoids overstressing of the shear fluid, especially in the radially outer region. This increases the service life of the shear fluid.

Further, on the negative side, the fluid clutch has a compact configuration. This is because the shear fluid is not exposed to local peak stresses, which would otherwise limit the maximum transmitted torque.

In a further advantageous embodiment, the width of the shear gap increases essentially directly in proportion to the radial distance from the axis of rotation. This increase is advantageously limited to the radial width of the shear gap between the suction opening and the pump device. Such a configuration provides a uniform shear stress across the shear fluid. The radially extending interstitial space is continuously and linearly widened.

Such a shear gap is particularly simple to manufacture.

For example, in hydraulic clutches, a considerable tilting play occurs between the two clutch parts, which tilting play has a significant influence on the shear gap width and thus on the transmitted torque. These disadvantages arise especially in the case of hydraulic clutches in which the shear gap extends approximately in the radial direction. The width of the radially outer region of such a fluid clutch can be varied relatively largely due to the tilting play. The outer region of the dust gap contributes significantly to the transmitted torque and is sensitive to changes in the parting width.

Such effects are also reduced by the present invention. This is because the inner region of the shear gap, which has a smaller width variation in the radial direction than the outer region due to the smaller shear gap width, is mostly used for torque transmission. In an advantageous embodiment, the average width of the shear gap region located radially inside the shear gap radius with the maximum width change caused by the tilting play is smaller than the average width of the shear gap radius. Advantageously, the average width of the shear gap at the radius with the maximum width change is set back equal to or slightly greater than the maximum width change, so that the fluid clutch is designed for as large a transmission torque as possible. .

In the case of a fluid clutch with a rotor in the form of a flat disc, the rotor has a constant thickness in the area of the surface forming the gap, whereas the gap in the working chamber has a constant thickness. The forming surfaces are suitably designed to obtain a radially outwardly expanding shear gap. In this way, the rotor is formed as a simple stamped part, whereas the shape of the surface forming the gap between the working chamber and the storage chamber is obtained by casting.

The invention will be explained below with reference to the exemplary embodiments shown.

The hydraulic clutch for a cooling fan according to FIG. 1 consists of a rotor 3 fixedly mounted on a shaft 1 and formed as an approximately flat disk, which rotor together with the shaft 1 extends along an axis of rotation 5. Rotate around the center. A clutch casing 7 is mounted on the shaft l in a manner not shown so that it can rotate freely relative to the rotor 3. Moreover, the shaft l is sealed relative to the clutch housing 7. The casings 7 are offset from each other in the circumferential direction and are arranged in the radial direction.
supports a plurality of fan blades 9 that separate from each other. A partition divides the interior of the casing 7 into a working chamber 13 surrounding the rotor 3 and a storage chamber 15 for a reservoir of viscous shear fluid, which is arranged axially adjacent to the working chamber 13. .

The rotor 3 has an approximately axially extending side surface 17.19, which side surface 17.19 corresponds to an oppositely located wall surface 21 of the working chamber 13.
Alternatively, together with 23, an approximately radially extending shear gap 25 or 27 is formed. During rotor operation, the shear gaps 25, 27 are filled with shear fluid, so that the rotor 3 exerts a torque on the casing 7 via the shear force transmitted by the shear fluid.

The fluid clutch can be engaged and disengaged in relation to temperature. In addition, the partition wall 11 is provided with a suction opening 33 with a radius of ≧ the filling level indicated by the reference numeral 31 of the disconnected clutch, which suction opening is provided with a shut-off valve, for example a shut-off in the form of a leaf spring 35. Closed by a valve.

A control member 37 opens the suction opening 33 of the shear fluid canister when a predetermined temperature increase is exceeded and closes the suction opening when the temperature increase is below. The control member 37 is
- Can be constructed as a metal strip or as an electrically controlled drive. The suction opening 33 opens into the working chamber and, as the case may be, in the area located radially inside the shear gaps 25 , 27 connected by the passage 38 in the rotor 3 . A return opening 39 is provided in the partition wall 11 near the outer periphery of the rotor 3 in an area located radially outside the working chamber 13;
The return opening together with the displacement member 41 forms a pumping device for returning the shear fluid from the working chamber 13 to the storage chamber 15 . In the case of a 3° connected hydraulic clutch, the shutoff valve of the suction opening 33 is opened;
This causes the shear fluid in the reservoir 15 to flow into the shear gap 25,27. The suction opening 33 is designed in such a way that a greater amount of shear fluid can flow into the working chamber 13 than the amount that is flowed back through the return opening 39 . The shear gaps 25 , 27 are filled with shear fluid and transmit the operating torque from the rotor 3 to the casing 7 .

After closing the suction opening 33, the displacement member 41 pumps the shear fluid from the working chamber 13 back into the storage chamber 15 until the clutch is released.

The shear gap 25,27 increases linearly as the radius increases starting from the inner radius r to the outer radius. The inner radius r 2 is equal to the distance between the axis 5 and the center line of the suction opening 33 . The outer radius ra approximately reaches the outer peripheral surface of the rotor 3. The shear stress of the local shear wheel and thus of the shear fluid is related to the coefficient of the differential velocity of the rotor 3 and the casing 7 for the width of the shear gap at the same radius. As mentioned earlier, when the width t of the shear gap -25, 27 increases in direct proportion to the radius r, a ratio r:t occurs and this causes the new shear vehicle to be within the limits of radii r1 and ra. is constant, and the ratio r, : t,
=ra: The value specified by ta. In this case, tl is the gap width at radius r, and the box is radius! This is the gap width at a. The shear fluid is therefore uniformly loaded at each radius within the shear gap 25,27.

In the case of conventional fluid clutches, the inner width of the shear gap is the same as the outer width, so that the shear force in each shear gap is larger at the outer circumferential surface than at the inner circumferential surface. Due to the constant width of the shear gap, in the case of conventional hydraulic clutches, the shear fluid is designed to increase the shear stress at the outer circumferential surface. The shear gap width ta of the fluid clutch according to the invention is designed from this point of view, i.e. the width of the shear gap decreases towards the axis of rotation 5, which provides significant advantages. It will be done.

In the radially inner region of the shear gap, a greater torque is transmitted than in the case of conventional hydraulic clutches with a constant gap width. Therefore, a high overall torque is transmitted by the fluid clutch according to the invention, and the fluid clutch can be designed in a continuous manner, provided that the i-lux is constant.

Furthermore, the delay in disengaging the fluid clutch is reduced. By tapering the shear gap in the radially inner range,
The shear gap volume is reduced and the pumping time is shortened. During pumping, first the radially inner region of the shear gap begins to be emptied. Because the portion of the torque transmission in the radially inner region of the shear gap is greater than in conventional hydraulic clutches, the torque initially decreases faster than in conventional hydraulic clutches upon disengagement of the hydraulic clutch.

Due to the narrowing of the shear gap width in the radially inner region, the radial width Δr of the shear fluid volume ΔV pumped from the shear gap per hour is determined in the case of the fluid clutch according to the invention by is much larger than that of a conventional fluid clutch. Furthermore, the storage volume of the shear fluid is
Due to the small volume of the shear gap, it can be designed to be small, so that in the case of the fluid clutch according to the invention, the shear generated by the shear fluid in the storage chamber 15 and which reacts on the fluid flow through the return opening 39 is reduced. The centrifugal pressure of the fluid becomes small.

The housing 7 can be supported with a slight tilting play relative to the shaft 1 or the rotor 3. In this case, the width ta of the rotor 3 at its outer circumferential surface is such that even if the rotor 3 is in an unfavorable tilted position relative to the casing 7, the shear fluid is not subjected to unacceptable stresses.

The width variation of the shear gap caused by the tilting play decreases as the axis of rotation 5 is approached. Shear gap 25.2
Even though 7 is tapered towards the axis of rotation 5, the relative width changes caused by the tilting play are constant at each location of the shear gap.

In a variant embodiment of the above-mentioned embodiment of a fluid clutch, the width ta of the shear gap 25.27 can also be designed wider than in the case of a conventional fluid clutch, in which case the associated radius A reduction in torque transmission in the outer range in direction is compensated by an increase in torque transmission in the inner range in radial direction. Moreover, due to the enlargement of the shear gap in the outer region, the idling torque and thus the idling torque of the hydraulic clutch is reduced. This provides advantages regarding noise generation and idling losses.

In the embodiment according to FIG. 1, the shear gap 25,27 is enlarged over its entire radial extent between the suction opening 33 and the return opening 39.

Moreover, the enlargement of the shear gap is limited in the radially inner range, whereas the radially outer range can be designed in another respect, in particular to improve the idling losses of the fluid clutch. You can also For example, in the radially outer region the shear gap can be designed to be constant, or it can have a different width change rate than in the radially inner region.

In the case of the hydraulic clutch according to FIG. 1, the side surfaces 21, 23 of the working chamber 13 extend parallel to each other and at right angles to the axis of rotation 5. The side surfaces 17, 19 of the rotor 3 are conically inclined towards each other. FIG. 2 shows a further embodiment which differs from the embodiment according to FIG. 1 only by the shape of the side surfaces. For a detailed explanation of the hydraulic clutch according to FIG. 2, reference is therefore made to the description according to FIG.

Elements having the same function in this case are numbered with an addition of 100. The fluid clutch according to FIG. 2 has a rotor 103 designed as a flat, substantially smooth disk, which rotor is arranged in a working chamber 113 of a casing 107. - side of the rotor in the axial direction 11
7 and the axial side surface 121 of the working chamber 113, and on the other hand between the axial rotor side surface 119 and the axial side surface 123 of the working chamber 113, a working gap extending approximately radially. 125 or 127 respectively, and the working gap widens radially from the inside to the outside.

However, for the fluid clutch according to FIG.
The side surfaces 11'7 and 119 of 03 are parallel to each other,
In contrast, the side surfaces 121, 123 are widened in the radial direction. In such embodiments, the rotor 103 is inexpensively stamped and formed from a thin sheet of constant thickness. Side 1
23 is a working chamber 113 and a storage chamber 11 for shear fluid;
5 is simply manufactured by casting the partition wall 111, which is also designed as a sheet-metal molded part.

FIG. 3 shows another embodiment of a fluid clutch for a fan of an internal combustion engine. The fluid clutch shown in FIG. 3 differs from the fluid clutch shown in FIG. 1 in the shape of the rotor and the arrangement of the shear gap.

In order to explain the hydraulic clutch according to FIG. 3, reference is made to the hydraulic clutch according to FIG. 1, in which identically acting elements are designated with the addition of 200.

The fluid clutch of FIG. 3 has a rotor 203 fixed to a shaft 201 and surrounded by a casing/207 supporting fan blades 209. A partition wall 211 divides the interior of the casing 207 into a working chamber 213 in which the rotor 203 is maintained and a storage chamber 215. A suction opening is indicated at 233 which allows the shear fluid to flow from the storage chamber 215 into the working chamber 213 .

The suction opening 233 is temperature-dependently controlled by a valve 235. The shear fluid is displaced by the displacement member 241.
The working chamber 21 is accessed through a return opening 239 formed in the partition wall.
3 and returned to the storage chamber 215.

The cup-shaped rotor 203 has a bottom part 251 extending perpendicularly to the axis of rotation 205, from which a hollow cylindrical wall part 253 projects in the axial direction. The radially outer circumferential surface 255 of the wall portion 2530 together with the radially opposite inner circumferential surfaces 257 of the casing 207 forms a shear gap 259 located radially outwardly of the rotor 203 . The partition wall 211 has a circumferential wall surface 261 that follows the inner contour of the rotor 203 in a conical manner and faces outward in the radial direction, and the circumferential wall surface radially faces the inner wall 263 of the wall portion 253. A second shear gap 265 is formed which is located inwardly and located inwardly. The shear gap 259,265 extends in the axial direction. Each of the shear gaps 259,265 is 1. It has a constant radial width over its axial length. The shear gap 265, which extends at a small radius, has a smaller radial width than the shear gap 259, which extends at a large radius. The radial width of both shear gaps is designed to have approximately the same shear width.

The axial side surface 251 of the bottom portion 251 is the casing 207
Alternatively, since the partition wall 211 has a large distance from adjacent side surfaces, the side surface 251 does not contribute to torque transmission. Moreover, the spacings can be reduced enough to produce a radially extending shear plan, as shown by the lines 267, 269 in FIG.

Such a shearing plan is advantageously designed in accordance with the embodiments of FIG. 1 or 2 and is expanded radially outwards.

In FIG. 3, wall portion 253 extends at right angles to bottom portion 251. In FIG. However, the wall portion 253 can extend at other angles to the bottom portion and can be curved continuously from the bottom portion.

In the case of the embodiment described above, the shear gap always increases linearly with increasing distance from the axis of rotation.

The width of the shear gap increases dramatically with increasing radius;
Alternatively, an embodiment in which the width change rate changes dramatically as the radius increases is also possible.

[Brief explanation of drawings]

FIG. 1 is a schematic partial vertical cross-sectional view of a fluid clutch according to the present invention, FIG. 2 is a partial vertical cross-sectional view showing another embodiment of the fluid clutch of the present invention, and FIG. 3 is a partial vertical cross-sectional view showing still another embodiment. FIG. 1... shaft, 3... rotor, 5... rotation axis, 7...
...Clutch casing, 9...Fan blade, 11.
...Partition wall, 13...Working room, 15...Storage room, 1
7,19...Side surface, 21.23...Wall surface, 25.2
7... Shear gap, 31... Filling rail, 33.
... Suction opening, 35... Leaf spring, 37... Control member, 38... Passage, 39... Return opening, 41...
Displacement member, 103... Mouth, 107... Casing, 113... Working chamber, 117, 119... Rotor side, 121.123... Working chamber side, 125,
127... Working gap, 201... Shaft, 203...
Rotor, 205...Rotation axis, 207...Casing, 209...Fan blade, 211...Partition wall, 2
13...Working room, '215...Storage room, 233...
・Suction opening, 235...Valve, 239...Return opening, 241...Pushing member, 251...Bottom part, 2
53...Wall portion, 255...Surrounding surface, 257...Surrounding surface, 259...Shear gap, 261...Surrounding wall surface, 26
3...Inner wall, 265...Shear gap, 267.2
69...broken line

Claims (1)

[Claims] 1. A temperature-controlled fluid clutch for a fan, comprising: (a) two clutch parts rotatable relative to each other about a common axis of rotation (5; 205); 3,7;
103, 107; 203, 207) and @) a working chamber (13; 113; 213) in the first clutch part (7; 107; 207) surrounding the second clutch part (3; 103; 203) and J (c) at least one shear gap (25, 27; 125, 127) extending at different radii between the mutually adjacent surfaces of the working chamber and the second clutch part and/or extending at different radii. Multiple shear gaps (259
, 265) and in) a storage chamber (15;
5; 215); (e) at least one suction opening (33; 233) for shear fluid leading from the storage chamber to the shear gap(s); a pump device (39, 41; 239, 241) extending into the storage chamber and radially outside the suction opening; (g) temperature-related controls for controlling the shear fluid flow through the suction opening or the pump device; valve (35
; 235),
The width of the shear gap(s) is designed in relation to the radial spacing between the shear gap(s) and the axis of rotation and increases in width as the spacing increases. A temperature controlled fluid clutch characterized by: 2. The second clutch part (3; 103) is formed as a disk, and both sides (17, 19; 11) of the disk
7,119), and the side surface (21,23; 121.123) adjacent to the disk side surface of the working chamber (13; 113).
) with one shear gap (25°27; 1
25, 127), and the shear gap expands radially outward. 3. Single or multiple shear gaps (25, 27; 1
25, 127) increases radially outwards in the radial region between the suction opening (33) and the pump device (39, 41). fluid clutch. 4. The disk (103) 73t has an approximately constant thickness, and the mutual distance between the surfaces (121, 123) of the working chamber (-113) forming both shear gaps (125, 127) is 3. A fluid clutch as claimed in claim 2 which increases radially outwardly. 5. The second clutch portion (203) has a tipped shape, and at least the outer peripheral surface (255) of the clutch portion
and an inner shear gap (265) and an outer shear gap (259) together with the adjacent surfaces (257; 261) of the working chamber (213) in the area between and the inner circumferential surface (263).
) and wherein the inner shear gap (265) has a narrower gap width than the outer shear gap (259). 6. Single or multiple shear gaps (25, 27; 12
5,127;259,265) is the width of the rotation axis (5;
6. A fluid clutch as claimed in any one of claims 1 to 5, in which the radial spacing from 205) increases substantially linearly. 7. Single or condensate shear gap (25, 27; 1
7. A hydraulic clutch according to claim 6, wherein the width of the diaphragm 25, 127) increases continuously with increasing distance from the axis of rotation (5). 8. One clutch part (7; 107) has limited tilting play and the other clutch part (1, 3; 103)
The shear gap or gaps (25, 27; 125, 127) extend between different radii and have a maximum width change caused by the tilting play. 2. A fluid clutch according to claim 1, wherein the average width of the shear gap range located radially inward of the radius (ra) is smaller than the average width of the shear gap radius (ra).