Housing unit for a separating clutch

Abstract

The invention relates to a housing unit (1) for a separating clutch (30), having a slave cylinder housing (10) and a transmission housing (20), wherein the slave cylinder housing (10) and the transmission housing (20) are arranged concentrically with respect to each other about a common longitudinal axis L, and the slave cylinder housing (10) is at least partly received in the transmission housing (20), wherein the transmission housing (20) has an outer wall opening (21a), wherein the slave cylinder housing (10) has an inner wall (11), an outer wall (12) and a bottom wall (13) which connects the inner wall (11) and the outer wall (12) to each other, wherein the inner wall (11), the outer wall (12) and the bottom wall (13) together bound a pressure chamber (14), and wherein the outer wall (12) of the slave cylinder housing (10) has at least one inlet opening (12a, 12b, 12c). Each of the one or more inlet openings (12a, 12b, 12c) is positioned below a central plane M which divides the transmission housing (20) into a first and a second half cylinder (H1, H2), wherein the outer wall opening (21a) of the transmission housing (20) lies centrally in the first half cylinder (H1) above the central line M in the circumferential direction of the transmission housing (20).

Description

[0001] Housing unit for a separating clutch

[0002] The invention relates to a housing unit for a clutch, in particular for a separating clutch of an electric motor vehicle or a motor vehicle with a hybrid drive.

[0003] As is known, separating clutches, also called KO clutches, are used to separate an electric motor from a combustion engine in a vehicle with a hybrid drive or to change gears in a vehicle with an electric motor.

[0004] A slave cylinder, also known by the abbreviation "CSC" (Concentric Slave Cylinder), is used to open and close such a separating clutch. The proper functionality of a slave cylinder is particularly important from a safety perspective, especially with separating clutches.

[0005] A slave cylinder typically comprises a housing, for example, made of a polymer with GF or aluminum, a piston housed in the housing, for example, made of a polymer with GF, a release bearing on which the piston acts, and a grooved seal, for example, made of EPDM or HNBR, depending on the fluid that actuates the slave cylinder. The grooved seal may be seated on a grooved seal carrier. The slave cylinder housing is typically mounted in a designated location in a transmission housing.

[0006] The transmission housing also features a fluid supply channel. The slave cylinder housing has an opening through which hydraulic fluid can flow into the slave cylinder housing and move the piston axially relative to a housing axis. A high-pressure connection between the transmission housing and the slave cylinder housing is conventionally sealed with O-rings.

[0007] However, it has been found that the combination of increased speed (> 6,000 rpm) and a misaligned clutch can lead to very high pressure fluctuations. These pressure fluctuations are introduced into the slave cylinder housing via the piston and then passed through the grooved seals into the hydraulic fluid. The fluid flows from an internal pressure chamber into an external pressure chamber and then into the high-pressure port in the transmission housing. If a pressure-controlled valve at an outlet of the pump injecting the hydraulic fluid detects excessive pressure, it opens to relieve the excess pressure. This behavior makes the vehicle unable to reach higher speeds when the combustion engine and electric motor are operating in parallel.

[0008] Furthermore, from the as yet unpublished DE 10 2022 133 994, a slave cylinder housing with three inlet openings is known, wherein the first inlet opening and the second inlet opening are diametrically opposed to each other and a third inlet opening is arranged at an angle of 90° to each of the first and second inlet openings, relative to a longitudinal axis L of the slave cylinder housing.

[0009] It is therefore an object of the invention to provide a housing unit with a slave cylinder housing for a separating clutch, with which pressure oscillations in a hydraulic system can be reduced.

[0010] This object is achieved according to the invention by a housing unit for a separating clutch according to claim 1 and a clutch unit according to claim 10. Preferred embodiments are specified in the subclaims.

[0011] For use in a separating clutch unit, the slave cylinder housing is installed in a transmission housing that at least partially encloses the slave cylinder housing. This creates an outer pressure chamber between the slave cylinder housing and the transmission housing. Hydraulic fluid supplied to the pressure chamber of the slave cylinder housing can flow outward and into the outer pressure chamber via the inlet openings of the slave cylinder housing.

[0012] A housing unit for a separating clutch according to the invention comprises a slave cylinder housing and a transmission housing, wherein the slave cylinder housing and the transmission housing are formed concentrically with each other around a common longitudinal axis L, and the slave cylinder housing is at least partially received in the transmission housing. The transmission housing comprises an outer wall opening on a cylindrical transmission housing outer wall.The slave cylinder housing has an inner wall, an outer wall and a bottom wall which connects the inner wall and the outer wall to one another, wherein the inner wall, the outer wall and the bottom wall together delimit a pressure chamber, and wherein the outer wall has at least one inlet opening, wherein each of the at least one inlet opening is positioned below a center plane M which divides the transmission housing into a first and a second half-cylinder H1, H2, wherein the outer wall opening of the transmission housing is located centrally in the first half-cylinder H1 in a circumferential direction of the transmission housing.

[0013] The inner wall, the outer wall and the bottom wall of the slave cylinder housing form a pressure chamber which is open to a side opposite the bottom wall to accommodate a piston which can slide in the pressure chamber under the action of a hydraulic fluid in the axial direction with respect to the longitudinal axis L in order to displace a release bearing which is connected to the separating clutch in the axial direction.

[0014] The at least one inlet port serves to allow the inflow and outflow of hydraulic fluid into and from the pressure chamber defined by the slave cylinder housing. When the slave cylinder housing is in use, wobbling movements of a piston housed in the slave cylinder occur due to a rotating, misaligned clutch in the motor vehicle's drivetrain. This generates pressure oscillations in the hydraulic fluid and leads to very rapid fluid movement within the slave cylinder housing. Hydraulic fluid is forced through the inlet ports from the pressure chamber of the slave cylinder housing into the outer pressure chamber between the slave cylinder housing and the transmission housing.

[0015] For this reason, according to the invention, the inlet opening or each of the inlet openings in the outer wall of the hydraulic cylinder is arranged below a center plane M of the housing unit. The center plane M of the housing unit is defined such that it divides the transmission housing and thus also the slave cylinder housing into two half-cylinders, so that the longitudinal axis L lies in the center plane M. The first half-cylinder is the one in which the outer wall opening of the transmission housing outer wall is located such that, in the circumferential direction with respect to the longitudinal axis L, it lies in the center of the transmission housing outer wall above the center plane M. In other words, in a cross-sectional view perpendicular to the longitudinal axis L, the outer wall opening divides the first half-cylinder H1 into two equal halves, which are approximately quarter cylinders. Each of the inlet openings of the slave cylinder housing is therefore located within the second half-cylinder H2, i.e.within the space spanned by the second half-cylinder H2 and the median plane.

[0016] Within the scope of the invention, the feature according to which the inlet openings are located below the center plane M is to be designed such that a center axis MÖ of each of the inlet openings running parallel to the longitudinal axis L is located below the center plane M of the housing unit.

[0017] This arrangement means that there is no inlet opening in the outer wall of the slave cylinder above the center plane M, and therefore no vent opening either. Thus, a certain amount of air is always trapped in the pressure chamber of the slave cylinder housing. This air acts as a kind of cushion and dampens the pressure oscillations in the housing unit. In particular, when a slave cylinder housed in the slave cylinder housing is actuated using a so-called "Smart Hydraulic" (SHA), the trapped air does not negatively impact the function of the slave cylinder. The target pressure and release travel specified for the slave cylinder are achieved despite the lack of a vent opening.

[0018] The flow openings for the hydraulic fluid required to actuate the slave cylinder are provided by the at least one inlet opening below the center plane M. As already mentioned, each of the inlet openings must be located below the center plane of the housing unit so that a minimum amount of air is trapped. The number and respective areas of the inlet openings are not mandatory and can be selected depending on requirements. For reasons of symmetry, however, it can be advantageous if the outer wall opening of the transmission housing is aligned with a first inlet opening in the outer wall of the slave cylinder housing. According to this embodiment, the first inlet opening of the slave cylinder housing is diametrically opposite the outer wall opening in the transmission housing outer wall across the center plane M.In this design, the hydraulic fluid flows from the outer wall opening of the transmission housing outer wall in the outer pressure chamber in equal parts on both sides of the slave cylinder housing to the first inlet opening.

[0019] Depending on requirements, several inlet openings can also be provided in the outer wall of the slave cylinder housing, evenly spaced from each other along the circumference. This also achieves the aforementioned symmetry.

[0020] According to a further embodiment of the invention, a diameter D of the outer wall opening of the transmission housing in a cross section perpendicular to the longitudinal axis L is smaller than a diameter d of each of the at least one inlet opening of the slave cylinder housing in a cross section perpendicular to the longitudinal axis L.

[0021] Furthermore, the at least one inlet opening and the outer wall opening of the transmission housing can be located at the same axial length relative to the longitudinal axis L. This allows for the supply of hydraulic fluid to the pressure chamber in the slave cylinder housing to be effected in a fluidically favorable manner.

[0022] According to a further advantageous embodiment, the inlet openings in the outer wall can be formed adjacent to the bottom wall. This design has proven particularly advantageous from a flow perspective.

[0023] The transmission housing can, in particular, have an inner transmission wall and a transmission housing base wall connecting the outer transmission wall to the inner transmission wall, with the base wall of the slave cylinder housing abutting the base wall of the transmission housing. Preferably, the inner wall of the slave cylinder housing also abuts the inner transmission wall. The slave cylinder housing is thus firmly inserted into the transmission housing. According to a further embodiment, the inlet opening(s) in the outer wall can each be formed adjacent to the base wall of the slave cylinder housing. In this way, a stroke path for the slave cylinder piston can be optimized.

[0024] The housing unit according to the invention has at least two O-rings placed between the outer wall of the transmission housing and the outer wall of the slave cylinder housing, each of which extends concentrically to the slave cylinder housing around the longitudinal axis L, wherein the at least one inlet opening or each of the inlet openings is positioned in the axial direction relative to the longitudinal axis L between two of the O-rings.

[0025] In summary, it should be noted that in the housing unit according to the invention, the transmission housing together with the outer wall of the slave cylinder housing or a part thereof form an outer pressure chamber which is connected, i.e. in fluid-conducting communication, to the pressure chamber of the slave cylinder housing via the inlet openings. Preferably, both the slave cylinder housing and the transmission housing are cylindrical and are at least partially open towards one end. The outer wall of the slave cylinder housing can be sealed off from the transmission housing by means of ring seals. The two housings can in particular have a common longitudinal axis L which coincides with a longitudinal axis of an electric motor for the motor vehicle.

[0026] A clutch unit according to one embodiment of the invention can comprise a separating clutch and a housing unit according to one of the preceding embodiments. In particular, the separating clutch and the slave cylinder housing are connected to each other via a release bearing, which is acted upon by a piston accommodated in the pressure chamber of the slave cylinder housing when the hydraulic fluid is pumped into the pressure chamber.

[0027] The invention is explained in more detail below using a non-limiting embodiment with reference to the drawing. The drawing shows:

[0028] Fig. 1 is a schematic view of a hybrid drive for a motor vehicle in which the invention can be used;

[0029] Fig. 2a; 2b a longitudinal sectional and a cross-sectional view through a housing unit of the prior art;

[0030] Fig. 2c, 2d diagrams showing the behavior of a hydraulic pressure in a straight and oblique separating clutch according to the prior art;

[0031] Fig. 3 shows a first embodiment of a housing unit according to the invention;

[0032] Fig. 4 shows a second embodiment of a housing unit according to the invention; and

[0033] Fig. 5 shows a third embodiment of a housing unit according to the invention.

[0034] Figure 1 shows a schematic view of part of a hybrid drive for a motor vehicle, which is designated in its entirety by the reference numeral 1000. The hybrid drive 1000 comprises a clutch unit 100 with a separating clutch 30 and a slave cylinder housing 10, which is received in a transmission housing 20. An outer wall opening 21a is formed in an outer wall 21 of the transmission housing, which opening serves to supply hydraulic fluid 200 from a reservoir 300 to the slave cylinder housing 10. In the embodiment shown, a so-called sump area 201 can also be seen, which has formed on the surface of the hydraulic fluid 200 in the reservoir 300.

[0035] The slave cylinder housing 10 is connected via a release bearing 60 to a spring means, which can be designed as a disc spring 50, as shown here, which in turn acts on the separating clutch 30. Thus, when hydraulic fluid 200 is conveyed from the reservoir 300, for example via a pump 90, to the transmission housing 20, wherein a check valve 80 can be placed between the pump 90 and the transmission housing 20 to prevent backflow, as can be seen here, the hydraulic fluid 200 can be pumped via the outer wall opening 21a of the transmission housing outer wall 21 to the slave cylinder housing 10 in order to actuate the separating clutch 30.

[0036] Both the slave cylinder housing 10 and the transmission housing 20 are cylindrical and arranged around a common longitudinal axis L of the slave cylinder housing 10. As can be seen, the electric motor 40 and the separating clutch 30 can also be positioned concentrically around the longitudinal axis L. In the embodiment shown, the transmission housing 20 and the slave cylinder housing 10 are axially offset from the electric motor 40 and the separating clutch 30 with respect to the longitudinal axis L. A further valve 70, which can be a pressure-controlled valve 70, is connected here in parallel to the pump 90 and the check valve 80 and also opens into the reservoir 300 for the hydraulic fluid 200.

[0037] This arrangement of the elements of the hybrid drive 1000 may correspond to the prior art. With reference now to Figures 2a and 2b, a housing unit T according to the prior art will be described in more detail, wherein the illustration in Figure 2a shows a longitudinal sectional view along the longitudinal axis L, and the illustration in Figure 2b shows a sectional view perpendicular thereto along the plane AA of Figure 2a.

[0038] The housing unit T comprises the slave cylinder housing 10 and the transmission housing 20, which are arranged concentrically to one another, wherein a pressure chamber 14 is formed on the slave cylinder housing 10, which is delimited here to the right by a bottom wall 13. The outer wall opening 21a can be seen in the transmission housing 20, which here extends perpendicular to the longitudinal axis L. An outer pressure chamber 24 is formed between an inner transmission housing wall 22 and the slave cylinder housing 10, which is sealed by a transmission housing bottom wall 23 and O-rings 25. A piston 15 is received in the pressure chamber 14 of the slave cylinder housing 10, which piston can slide parallel to the longitudinal axis L when hydraulic fluid 200 is supplied through the outer wall opening 21a of the transmission housing 20 within the pressure chamber 14. The piston 15, as can be seen here, can be sealed against the pressure chamber 14 with a grooved sealing ring 26, which may be seated on a sealing ring carrier.

[0039] Inlet openings 12a', 12b', 12c' are provided in an outer wall 12 of the slave cylinder housing 10 in order to fluidly connect the inner pressure chamber 14 with the outer pressure chamber 24.

[0040] With reference to Figures 2c and 2d, a disadvantage of the prior art housing unit 1' of Figure 2c will now be explained. If the separating clutch 30 is straight, as is the case in the diagram of Figure 2c, the pressure fluctuations of the hydraulic fluid 200 in the clutch unit 100 are limited. The diagram shows a hydraulic pressure over an angle in the transmission housing. If, on the other hand, the separating clutch 30 is oblique, as in the case of the diagram of Figure 2d, high pressure fluctuations can be seen in the transmission housing. In this case, the valve 70 (see Figure 1), which is a pressure-controlled valve, opens and thus releases pressure from the housing.

[0041] Figure 3 shows a housing unit 1 according to an embodiment of the invention in cross-section perpendicular to the longitudinal axis L (see Figure 1). The housing unit 1, like the housing unit 1 of the prior art, comprises the slave cylinder housing 10 and the transmission housing 20, wherein the transmission housing 20 comprises a transmission housing outer wall 21 with an outer wall opening 21a, a transmission housing inner wall 22 and a transmission housing bottom wall 23. Here, too, the slave cylinder housing 10 comprises the inner wall 11, the outer wall 12, between which the pressure chamber 14 is formed. Between the outer wall 12 of the slave cylinder housing 10 and the transmission housing inner wall 22, the outer pressure chamber 24 is formed, which is connected to the pressure chamber 14 via a first inlet opening 12a and a second inlet opening 12b in the outer wall 12 of the slave cylinder housing 10.

[0042] As can be seen in the figure, the transmission housing 20 and thus also the slave cylinder housing 10 are divided by a center plane M into two equally sized half-cylinders H1, H2. In this illustration, the center plane M runs perpendicular to the image plane and contains the longitudinal axis L. The outer wall opening 21a of the transmission housing 20 is located in the circumferential direction relative to the longitudinal axis L centrally in the first half-cylinder H1, i.e. centrally in the transmission housing outer wall 21 above the center plane M.

[0043] Unlike the prior art, in the embodiment of the invention the first inlet opening 12a and the second inlet opening 12b are located below the center plane M, i.e. in an area spanned by the second half-cylinder H2 and the center plane M. In other words, the outer wall opening 21a and the first and second inlet openings 12a, 12b are located on opposite sides with respect to the center plane M. The fact that the inlet openings are located below the center plane M means that a center axis MÖ of each of the inlet openings, running parallel to the longitudinal axis L, is located below the center plane M of the housing unit, as can be seen in the figure. The center axis MÖ of each of the inlet openings 12a, 12b therefore runs perpendicular to the image plane, i.e. perpendicular to the cross-sectional plane.Since there are no inlet openings 12a, 12b in the area of ​​the first half-cylinder H1, air bubbles B form there, which dampen the pressure oscillations of the hydraulic fluid 200 that arise when the housing unit 10 is used in a coupling unit 100 (see Figure 1).

[0044] This configuration allows pressure oscillations of the hydraulic fluid 200 in the pressure chamber 14 to be significantly reduced. As can also be seen, a diameter d of the two inlet openings 12a, 12b is larger than a diameter D of the outer wall opening 21a, in each case viewed in the sectional plane shown here perpendicular to the longitudinal axis L of the housing unit 1. With reference to Figures 4 and 5, a second and a third embodiment of a housing unit 10 according to the invention are shown. In these embodiments, too, in the respective cross-sectional view shown, the center plane M, which contains the longitudinal axis L, divides the housing unit 10 into two halves, with the outer wall opening 21a of the transmission housing outer wall 21 being located in a first half (the upper half in the illustration) and the respective inlet openings 12a, 12b, 12c each being completely in the other half (the lower half in the illustration).Figure 4 shows three inlet openings 12a, 12b, 12c, which are equally spaced from one another and identical. In contrast, the embodiment of Figure 5 has only a first inlet opening 12a, which is diametrically opposite the outer wall opening 21a across the center plane M.

[0045] In none of the embodiments is there an inlet opening in the first half of the space defined by the center plane M, neither an inlet opening for the passage of a hydraulic fluid nor a so-called vent opening. As a result, some trapped air always remains in the upper half, which dampens pressure oscillations occurring there when the housing unit 1 according to the invention is used in a clutch unit.

[0046] List of reference symbols

[0047] 1 ' housing unit (state of the art)

[0048] I Housing unit

[0049] 10 Slave cylinder housing

[0050] II Interior wall

[0051] 12 exterior wall

[0052] 12a first inlet opening

[0053] 12b second inlet opening

[0054] 12c third inlet opening

[0055] 13 Floor wall

[0056] 14 Printing room

[0057] 15 pistons

[0058] 20 gearbox housing

[0059] 21 Gearbox housing outer wall

[0060] 21a Exterior wall opening

[0061] 22 Gearbox housing inner wall

[0062] 23 Gearbox housing base wall

[0063] 24 outer pressure chamber

[0064] 25 O-ring

[0065] 26 Groove seal

[0066] 30 Separating coupling

[0067] 40 electric motor

[0068] 50 disc springs

[0069] 60 release bearings

[0070] 70 valve

[0071] 80 check valve

[0072] 90 pump

[0073] 100 coupling unit

[0074] 200 Hydraulic fluid 201 Swamp area

[0075] 300 reservoirs

[0076] 1000 hybrid drive

[0077] L common longitudinal axis

[0078] M Mid-level housing unit

[0079] MÖ central axis opening

[0080] B Air bubble

Claims

Patent claims 1 . Housing unit (1) for a separating clutch (30), comprising a slave cylinder housing (10) and a transmission housing (20), wherein the slave cylinder housing (10) and the transmission housing (20) are arranged concentrically to one another around a common longitudinal axis L and the slave cylinder housing (10) is at least partially received in the transmission housing (20), wherein the transmission housing (20) has an outer wall opening (21a) on a cylindrical transmission housing outer wall (21), wherein the slave cylinder housing (10) has an inner wall (11), an outer wall (12) and a bottom wall (13) which connects the inner wall (11) and the outer wall (12) to one another, wherein the inner wall (11), the outer wall (12) and the bottom wall (13) together delimit a pressure chamber (14), and wherein the outer wall (12) of the slave cylinder housing (10) has at least one inlet opening (12a, 12b, 12c), characterized in that each of the at least one inlet opening (12a, 12b,12c) is positioned below a center plane M which divides the transmission housing (20) into a first and a second half-cylinder (H1, H2), wherein the outer wall opening (21a) of the transmission housing (20) is located centrally in the first half-cylinder (H1) above the center line M in a circumferential direction of the transmission housing (20).

2. Housing unit (1) according to claim 1, characterized in that the outer wall opening (21 a) of the transmission housing (20) is aligned with a first inlet opening (12 a) of the outer wall (12) of the slave cylinder housing (10).

3. Housing unit (1) according to claim 1 or 2, characterized in that a plurality of inlet openings (12a, 12b, 12c) are provided, which are circumferentially evenly spaced from one another.

4. Housing unit (1) according to one of the preceding claims, characterized in that a diameter D of the outer wall opening (21a) of the gear housing (20) in cross section perpendicular to the longitudinal axis L is smaller than a Diameter d of each of the at least one inlet opening (12a, 12b, 12c) of the slave cylinder housing (20) is perpendicular to the longitudinal axis L in cross section.

5. Housing unit (1) according to one of the preceding claims, characterized in that the at least one inlet opening (12a, 12b, 12c) and the outer wall opening of the gear housing (20) are located on the same axial length with respect to the longitudinal axis L.

6. Housing unit (1) according to one of the preceding claims, characterized in that the transmission housing (20) has a transmission housing inner wall (22) and a transmission housing bottom wall (23) connecting the transmission housing outer wall (21) thereto, wherein the bottom wall (13) of the slave cylinder housing (10) bears against the transmission housing bottom wall (23).

7. Housing unit (1) according to claim 6, characterized in that the inner wall (11) of the slave cylinder housing (10) rests against the transmission housing inner wall (22).

8. Housing unit (1) according to one of the preceding claims, characterized in that the inlet openings (12a, 12b, 12c) are formed in the outer wall (12) adjacent to the bottom wall (13).

9. Housing unit (1) according to one of the preceding claims, characterized in that at least two O-rings (25) are placed between the transmission housing outer wall (21) and the outer wall (12) of the slave cylinder housing (10), which O-rings each extend concentrically to the slave cylinder housing (10) about the longitudinal axis L, wherein each of the at least one inlet opening (12a, 12b, 12c) is positioned in the axial direction relative to the longitudinal axis L between two of the O-rings (25).

10. Coupling unit (100) comprising a separating clutch (30) and a housing unit (1) according to one of the preceding claims.

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