WO2000030911A1

WO2000030911A1 - Main cylinder

Info

Publication number: WO2000030911A1
Application number: PCT/EP1999/009000
Authority: WO
Inventors: Harald KÖNIG; Udo Jungmann; Andreas Bischoff
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 1998-11-24
Filing date: 1999-11-23
Publication date: 2000-06-02
Also published as: DE19854106A1

Abstract

The invention relates to a main cylinder, especially a tandem main brake cylinder for hydraulic dual circuit brake systems of motor vehicles. The basic design of said main cylinder comprises a housing (1) with a longitudinal bore (2) for at least one piston (3, 4) guided in said bore. Said piston (3, 4) acts on at least one pressure chamber (5, 6) in the housing (1). In the area of the pressure chamber (5), a valve (8) is arranged in a bore (7) of the housing (1). Said valve is opened when the piston (3) is relieved for the purpose of pressure compensation between the pressure chamber (5) and a container (9) which is preferably connected to the bore (7). To build up pressure in the pressure chamber (5) when the piston (3) is charged, said valve (8) is closed. An actuator element (10) is assigned to the piston (3). Said actuator element projects over the front face (3a) of the piston and opens and closes the valve (8).

Description

Master cylinder

The invention relates to a master cylinder, in particular a tandem master cylinder for hydraulic dual-circuit brake systems of motor vehicles, with a housing with a longitudinal bore for at least one piston guided therein, which works on at least one pressure chamber in the housing, and with at least one in a bore in the housing in the region of the pressure chamber Arranged valve which is opened to equalize pressure between the pressure chamber and a liquid container preferably connected to the bore when the piston is unloaded, and which is closed to build up pressure in the pressure chamber when the piston is loaded or acted upon.

Such a master cylinder is usually actuated by foot power and / or an auxiliary force, for example compressed air, vacuum, hydraulic pressure, etc. As is known, the entire braking process of a motor vehicle is initiated and controlled via the master cylinder. When the brake pedal is pressed, the piston of the master cylinder usually presses brake fluid, which is located in the brake system, into the associated disc brake or wheel cylinder.

The aforementioned bore, which is arranged in the region of the pressure chamber and which is also referred to as a compensating bore in connection with a primary sleeve possibly provided on the piston, must be open when the brake is released, that is to say when the piston is relieved, in order to and to ensure pressure equalization in the brake system. Such a balance between a liquid container usually connected to the bore and the pressure chamber is necessary because the (brake) liquid enclosed in the master cylinder, in the line network and in the actuating cylinders (disc brakes or wheel cylinders) is subject to influences which require a change in quantity and pressure .

A master cylinder of the structure described in the introduction has become known from the German designation 20 65 012. A comparable embodiment is the subject of German specification 21 64 590. Both of the above-described teachings have in common that the master cylinder has a relatively long construction, inter alia because the bore associated with a primary or push rod piston and the bore associated with a secondary or intermediate piston are far apart and consequently the or the liquid containers connected to it are constructed to extend. In any case, the known master cylinders cannot satisfy their size, also with a view of a vacuum brake booster that is usually connected upstream. - The invention as a whole wants to remedy this.

The invention is based on the technical problem of developing a master cylinder of the construction described at the outset in such a way that a significant reduction in the overall length is achieved, in particular in combination with a vacuum brake booster.

To achieve this object, the invention proposes in a generic master cylinder, in particular a tandem master cylinder for hydraulic dual-circuit brake systems of motor vehicles, that a piston-controllable and actuating element projecting over its end face is provided for the automatic opening and closing of the valve. This actuating element can be a cylinder sleeve which is guided in the housing and released by the piston in the course of its action. According to a further preferred embodiment, this actuating element has a front bevel for an actuating tappet that controls the valve and is generally supported on the housing with the interposition of a spring, the spring acting on the actuating element to close the valve when the piston is loaded. - In this way, the size of the housing of the master cylinder is first significantly reduced without changes to the dimensions of the push rod piston and intermediate piston are required. In essence, this can be attributed to the fact that the push rod piston can for the most part be arranged outside the housing and is no longer used directly to control the valve. Rather, a kind of indirect control is possible via the actuating element designed as a cylinder sleeve, because this protrudes over the end face of the piston.

Accordingly, the two bores for the primary and secondary circuit can be arranged in the immediate vicinity of one another, so that the liquid container generally connected to it can also be made compact. The result of this is that the housing can have a relatively long insertion or installation area for a receiving bore of an upstream vacuum brake booster. In any case, the overall size or overall length is significantly reduced, which not only brings advantages when installing and assembling with existing units, but also in terms of weight Terms is important. This is where the essential advantages of the invention can be seen.

According to a further advantageous embodiment, it is provided that the actuating element, when the piston is relieved, rests with a bottom inner ring collar on a stop ring of the piston which overlaps the inner ring collar. When the piston is relieved, the stop ring moves away from the inner ring collar, releasing the actuating element. The stop ring limits the stroke exerted by the spring supported on the housing on the actuating element. This is necessary so that the actuating element or the cylinder sleeve is at a defined distance from another piston guided in the longitudinal bore. It should be emphasized that the configuration according to the invention can relate both to the primary or push rod piston and to the secondary or intermediate piston. Of course, cumulative configurations are also conceivable in which both the secondary and the primary piston have the described actuating element and associated valves are provided.

The spring already mentioned between the housing and the cylinder sleeve or the inner ring collar on the bottom side ensures a sensitive and tilt-free response of the valve tappet and thus the valve. This is necessary because the linear movement of the cylinder sleeve in the axial direction of the longitudinal bore is generally converted into a vertical lifting and lowering movement of the valve lifter. This preferably has a cross-shaped cross section with a foot-side overrun pin, a tappet plate connected to it and a head-side guide pin. The aforementioned run-up pin works with the one already described Sloping ramp for converting the linear movement in question into the vertical movement together.

The sealing of the bore and thus of the valve takes place according to a further preferred embodiment in such a way that the valve has a valve housing with a bottom bore for the valve tappet guided therein, and that the valve has a sealing ring on the inside of the housing with a guide bore for the valve tappet and circumferential seal for the tappet plate which can be attached to it owns. In other words, the tappet plate which can be sealingly applied to the peripheral seal ensures reliable closure of the valve and thus of the bore. For this purpose, the valve tappet plate can be hat-shaped and have a hat head that can be placed on the peripheral seal and a hat ring that is supported on the valve housing. This hat ring may have additional circumferential holes to ensure a rapid flow in the course of the pressure equalization when the valve is open.

So that the valve tappet can be aligned sensitively (in the vertical direction) compared to the run-up slope, the invention provides, according to a further preferred embodiment, that the valve housing is designed as a screw-in housing with an external thread. In this way, it is not only possible to achieve a problem-free assembly of the valve housing, but also a vertical alignment of the valve housing is possible. Depending on the screwing depth of the valve housing into the housing of the master cylinder, the protrusion of the overrun pin into the housing can be varied and thus also the stroke of the valve tappet. The invention is explained in more detail below on the basis of two exemplary embodiments, which are illustrated in the drawing. Show it:

FIG. 1 shows a longitudinal section through a master cylinder according to the invention,

FIG. 2 shows an enlarged detail from FIG. 1 in the region of the valve,

FIG. 3 shows a second exemplary embodiment of the invention in longitudinal section and in the unactuated state,

Figure 4 shows the second embodiment in longitudinal section and with a different cut, and

Figure 5 master cylinder of Figure 4 in the actuated state.

The figures show a master cylinder, a tandem master cylinder for a hydraulic dual-circuit brake system of a motor vehicle according to the exemplary embodiment. In its basic structure, this master cylinder has a housing 1 with a longitudinal bore 2 for at least one piston 3, 4 guided therein. According to the illustration shown, the pistons 3, 4 are a primary or push rod piston 3 as well as a secondary or intermediate piston 4. Each of the two pistons 3, 4 works on an associated pressure chamber 5, 6. The pressure chamber 5 belongs to the primary one Piston 3, while the secondary piston 4 acts on the pressure chamber 6. Both pressure chambers 5, 6 are located in the housing 1, and are defined between a chamber bottom and the associated housing wall. Furthermore, there is a valve 8 arranged in a bore 7 of the housing 1 in the region of the pressure chamber 5. This valve 8 is opened for pressure equalization between the pressure chamber 5 and a liquid container 9 connected to the bore 7, specifically when the piston 3 is unloaded in the pressure chamber 5 when the piston 3 is loaded, the aforementioned valve 8 is closed. The opening and closing movement of the valve 8 takes place via an actuating element 10, which projects beyond an end face 3a of the piston 3 and accordingly opens and closes the valve 8, specifically controlled by the piston 3.

For this purpose, the actuating element 10 is designed in detail as a cylindrical sleeve 10 which is guided in the housing 1 and supported on the housing 1. The actuating element or the cylinder sleeve 10 has a front bevel 11 for a valve tappet 12 controlling the valve 8. Accordingly, a movement of the cylinder sleeve 10 in the axial direction H of the longitudinal bore 2 is converted into a corresponding vertical adjustment in the vertical direction V of the valve lifter 12. Of course, the angle of the run-up slope 11 with respect to the axial or horizontal direction H influences the "transmission ratio" into the vertical movement in the vertical direction V.

The actuating element or the cylinder sleeve 10 is supported on the housing 1 with the interposition of a spring 13. This spring 13 is, according to the exemplary embodiment, two disc springs resting against one another, which rest on a disk 14. Of course, conventional helical springs (comparable to FIGS. 3 to 5) or corrugated washers or helical springs made of corrugated flat steel can also be used here Come into play. This disc 14 is in turn a head-side component of a ring insert 15 of the housing 1, in which the piston 3 is guided in a sealing manner. When the piston 3 is loaded, ie moving to the left in FIG. 1, the spring 13 acts on the actuating element 10 to close the valve 8, because then a corresponding movement of the actuating element or the cylinder sleeve 10 (also to the left) is released.

In detail, this is done constructively so that the actuating element 10 rests with a bottom inner ring collar 16 on a stop ring 17 of the piston 3, namely when the piston 3 is relieved. This stop ring 17 engages over the aforementioned inner ring collar 16. When the piston 3 is relieved, the actuating element 10 consequently shifted to the right in FIG. 1 until it abuts an associated stop 18 of the housing 1. This stop 18 defines the rest or relief position of the piston 3, as it were, in this position the spring 13 is compressed. When loaded, the stop ring 17 of the piston 3 moves away from the inner ring collar 16, which - spring-loaded by the spring 13 - moves like the piston 3 to the left in FIG. 1. The actuating element 10 is now released. At the same time, the actuating plunger 12 of the valve 8 in FIG. 1 is adjusted upward, namely by its running up on the front run-up slope 11 of the actuating element 10.

With reference to FIG. 2, it can be seen that the valve tappet 12 has a cross-shaped cross section with a foot-side run-up pin 12a, a tappet plate 12b connected to it and a head-side guide pin 12c. In addition, the Valve 8 is a valve housing 19 with a bottom bore 20 for the valve tappet 12 or run-up pin 12a guided therein.

The sealing function of the valve 8 is performed by a sealing ring 21 on the inside of the housing, which is held in the valve housing 19 by means of a support body 22. This support body

22 or the sealing ring 21 has a guide bore 22 'for the valve lifter 12 or its guide pin 12c. The support body 22 serves to receive a peripheral seal

23 for the tappet plate 12b that can be attached to it. This tappet plate 12b is hat-shaped and has a hat head 24 which can be attached to the peripheral seal 23 and a brim-like hat ring 25 which is supported on the valve housing 19. In order to ensure the fastest possible pressure equalization through the bore 7 or the valve 8, openings 26 on the circumference are provided in the cap ring 25. The valve housing 17 has a stop 27 adapted to the hat shape of the tappet plate 12b, on which a valve housing spring 28 stands and is supported with respect to the hat ring 25.

The valve housing 19 is a screw-in housing with an external thread 29. In this way, the valve housing 19 can be installed in a particularly simple manner. Such an external thread 29 also allows an adjustment in the vertical direction V in order to match the run-up pin 12 a and run-up slope 11 for a proper function of the valve 8. The valve housing 19 is made of steel according to the exemplary embodiment, while the housing 1 of the master cylinder can be predominantly made of aluminum in order to achieve the greatest possible weight savings. Finally, it can be seen from FIG. 1 that, due to the actuating element 10 used according to the invention, a large part of the master cylinder or its housing 1 can be inserted or inserted into a vacuum brake booster, not shown. For example, the master cylinder shown can be inserted into such a brake booster up to an installation stop 30. This significantly reduces the overall size and provides a compact brake actuation module.

Figures 3 to 5 show a second embodiment of the invention. Corresponding components have the same reference numerals, and modified components are identified by the same reference numerals and '. 3 shows a sectional view to illustrate a valve 8 'assigned to the primary pressure chamber 5, while FIGS. 4 and 5 show a valve 8' 'assigned to the secondary pressure chamber 6.

Accordingly, the housing 1 'has a bore 7' for a valve 8 'and is arranged parallel to a longitudinal bore 2' for guiding the piston 4. The piston 3, which is decisive for the actuation of the valve 8 ', can be moved axially within a cylindrical guide of a cartridge-shaped housing part 1 a' provided concentrically with the bore 2 '. The guide for the piston 3 has a smaller diameter than the bore 2 '. Basically, the cartridge la 'is preferably made of sheet metal, which was formed in a deep-drawing process and punched to size, so that essentially only the housing part 1' is preferably made from a light metal material in a casting process. The housing 1 'has the longitudinal tion 2 'and the bore 7' in contrast to FIGS. 1 and 2 via a plurality of parallel longitudinal bores arranged at a distance from one another, which can be carried out inexpensively in one working and clamping process, for example with a multi-spindle boring machine. Even if the drawing shows that the (blind) bores 2 ', 7' are open on different sides, a further simplification of manufacture and assembly can be achieved by providing a uniform opening side (in particular in the direction of the cartridge 1 a ') is, so that the assembly of the pistons and their sealant, as well as the assembly of the valve 8 'together with accessories can be done from a single side within a single housing clamping. This also eliminates the need for any of the (blind) bores 2 ', 7' to be closed with a lid or stopper. In other words, the above measure saves considerable costs. With regard to the overall length of the master brake cylinder, it is also relevant that the valve 8, 8 ', 8''responsible for the respective brake circuit or parts thereof are aligned with a hydraulic connection 35 for a line or a (brake) fluid container and aligned with at least part the piston 4 is arranged. Fig. 5 shows that even part of the piston 3 is aligned with part of the valve. It is therefore advisable that not only the valve 8 'for the pressure chamber 5 acted upon by the piston 3 (primary or pressure rod circuit), but also a valve 8''for the pressure chamber 6 acted on by the piston 4 (secondary circuit) with the mentioned components are aligned, which saves considerable length.

An actuating element 10 'ensures that each valve 8', 8 '' is in the open position in the open position. remains, although the body of the valve 8, 8 ', 8''is under the pretensioning force of an elastic means, in particular a helical spring 36, and consequently fundamentally seeks to get into the closed position by contacting a valve seat 44. For this purpose, the actuating means 10 'in the unactuated state of the master cylinder under tension is arranged between the piston 3 and the valve 8' in such a way that it exerts a preloading force on the valve stem 12 'of the valve 8' and retains it in the open position. The retraction force is applied by return springs 46, 47, which basically serve to hold the pistons 3, 4 in an unactuated end position. The effect of the actuating means 10 'takes place in that its connection to the piston 3 (and thus to the retraction force) is released, because the piston is pressed to the left in the figure as part of the normal brake actuation, so that the actuating element is released by the piston , and can also move to the left in the actuating direction under the biasing force of a spring 13 'resting on the housing 1'. This movement in turn cancels the retraction function on the valve lifter 12 ', so that the elastic means 36 takes effect and forces the valve body to close. In this context, it would be easily conceivable to combine the action of elastic means 36 and spring 13 'in a single resilient component.

As the figure also shows, the actuating element 10 'comprises two relatively displaceable and socket-like components 37, 38 which are spaced apart from one another and are telescopic such that with increasing actuation there is an increasing shortening of the total length of the actuating element 10', and vice versa. The maximum reduced overall length can be seen in FIG. 5. The actuating element 10 'is pushed into one another such that the remaining overall length is determined to a certain extent by the overall length of the longest bush 37, 38. Each of the socket-shaped components 37, 38 has at least one positively acting driver element in the manner of a radial flange 40. To further optimize the manufacturing properties, the (retraction) force transmission between piston 3 and valve lifter 12 'takes place via the individual, functionally adjacent components with the aid of uniform, form-fitting driver elements, namely radial flanges 41, 42, 43 which act on the relevant functionally adjacent component . At least one of the flanges in the figure, the flange 43 engaging the plunger 12 ', also serves to support the spring 13' which is applied to the housing 1 a 'under pretensioning force. Finally, at least one of the two sleeve-shaped components 37, 38 is preferably, as shown in the figure, guided in the region of the radial flange 42 on a wall 39 of the housing 1 a '.

Each valve 8 'also includes a valve seat 44 which is fixedly supported in the bore 7' and is stationary with respect to the housing. To simplify assembly, it may be advisable to arrange the valve seat 44 firmly on a holding body 45 which can be screwed into the bore 7 ' or can be pressed in a pressure-tight manner.

Even if a snap ring 48 has been provided as a piston-side driver element according to FIGS. 3-5, which is inserted into a groove in the wall of the piston 3, so that the snap ring points radially inward, it is entirely conceivable for the driver element to be of the same type radially to be provided on the outside of the piston 3, as is basically shown in FIG. 1. This has the advantage that the tubular piston front part only has to take up a return spring, which is particularly effective with small piston diameters.

In the foregoing, the function and structure of the master brake cylinder have been described essentially only with regard to one brake circuit, namely the pressure rod brake circuit acted upon by the piston 3, using the pressure chamber 5. It goes without saying that in the case of double-circuit cylinders, a valve 8 ″ for the secondary circuit is also to be provided, which is illustrated in FIG. 4 by using the same reference numbers and an identification by ″. However, an actuating element 10 ″ assigned centrally to the piston 3 is responsible for actuating the two valves 8 ′ and 8 ″.

In addition, the above invention is not only limited to the advantages already described, but also intervenes advantageously in other areas. For example, the above construction enables an improved suction of brake fluid from the brake fluid reservoir through the master brake cylinder, because the channel guide enables particularly low hydraulic resistances.

It applies to all embodiments that the function of the secondary or intermediate piston 4 shown essentially corresponds to well-known configurations. In this regard, reference is made to the relevant prior art, for example DE-AS 20 62 540. Of course, it is within the scope of the invention, the described Assign the configuration instead of the push rod piston 3 to the secondary piston 4 without leaving the invention.

Claims

Patent claims

1. Master cylinder, in particular tandem master brake cylinder for hydraulic dual-circuit brake systems of motor vehicles, with a housing (1,1 ', 1a') with a longitudinal bore (2,2') for at least one piston (3,4) guided therein, which is on at least one Pressure chamber (5,6) in the housing (1,1 ', 1a') works, and with at least one in a bore (7,7', 7'') of the housing (1,1', 1a') in the area of Valve (8, 8 ', 8'') arranged in the pressure chamber (5, 6), which is used to equalize the pressure between a pressure chamber (5, 6) and a liquid container (9) which is preferably connected to the bore (7, 7', 7''). ) is opened when the piston (3) is relieved, and which is closed to build up pressure in the pressure chamber (5,6) when the piston (3) is loaded, characterized in that a cantilever which can be controlled by the piston (3) and protrudes over its end face (3a). Actuating element (10,10') is provided for opening and closing the valve (8,8',8'').

2. Master cylinder according to claim 1, characterized in that the actuating element (10, 10 ') is a cylinder sleeve (37, 38) which is guided in the housing (1, 1 ', 1a') and can be released by the piston (3) in the course of its action ) is trained.

3. Master cylinder according to claim 1 or 2, characterized in that the actuating element (10) has a front ramp (11) for a valve tappet (12) controlling the valve (8).

. Master cylinder according to one of claims 1 to 3, characterized in that the actuating element (10, 10') is supported on the housing (1, 1a') with the interposition of a spring (13, 13'), the spring (13, 13' ) when the piston (3) is loaded, the actuating element (10,10') is acted upon to close the valve (8,8',8'').

5. Master cylinder according to one of claims 1 to 4, characterized in that the actuating element (10) when the piston (3) is relieved with a bottom-side inner ring collar (16) on a stop ring (17) of the piston (3) which overlaps the inner ring collar (16). rests, whereby the stop ring (17) moves away from the inner ring collar (16) when the piston (3) is loaded, releasing the actuating element (10).

6. Master cylinder according to one of claims 1 to 5, characterized in that the valve (8) has a valve housing (19) with a bottom bore (20) for the valve tappet (12) guided therein.

7. Master cylinder according to one of claims 1 to 6, characterized in that the valve (8) has a sealing ring (21) on the inside of the housing with a guide bore (22 ') for the valve tappet (12) and a peripheral seal (23) for a tappet plate that can be placed thereon (12b).

8. Master cylinder according to one of claims 1 to 7, characterized in that the tappet plate (12b) is hat-shaped and has a hat head (24) which can be placed on the circumferential seal (23) and a has a hat ring (25) which is supported on the valve housing (19).

9. Master cylinder according to one of claims 1 to 8, characterized in that the valve housing (19) is designed as a screw-in housing with an external thread (29).

10. Master cylinder according to one of claims 1 to 9, characterized in that the valve tappet (12) has a cross-like cross section with a base-side run-on pin (12a), a tappet plate (12b) connected thereto and a head-side guide pin (12c).

11. Master cylinder according to one or more of claims 1 to 10, characterized in that the bore (7 ', 7'') for the valve (8 ', 8'') is parallel to the longitudinal bore (2 ') for the piston ( 4) is arranged, and that at least parts of the valve (8 ', 8'') are arranged in alignment with a hydraulic connection (35) for a hydraulic line or a container and in alignment with at least part of the piston (4).

12. Master cylinder according to claim 11, characterized in that the valve (8 ', 8'') can be moved into the closed position with an elastic means (36) under a prestressing force, and the actuating element (10') in the unactuated state between Piston (3) and the valve (8') is arranged so that it exerts a retraction force on the valve (8', 8'') that overcomes the preload force and holds it in an open position.

3. Master cylinder according to claim 12, characterized in that the actuating element (10 ') comprises at least two relatively displaceable and socket-like components (37, 38), which are arranged telescopically at a distance from one another in such a way that with increasing actuation there is an increasing shortening of the overall length of the actuating element (10') occurs, and vice versa.

14. Master cylinder according to claim 13, characterized in that at least one of the two components (37,38) is arranged to be slidably guided on a wall (39) of the housing (l ¹ ).

15. Master cylinder according to at least one of the preceding claims 13 or 14, characterized in that each of the socket-shaped components (37,38) has at least one radial flange (39,40,41,42) which is used for power transmission to an adjacent component, namely the adjacent socket element (37, 38), the piston (3) or a valve component, in particular a valve tappet (12 ').

16. Master cylinder according to claim 15, characterized in that at least one flange (43) is provided for contact with an adjacent component (12 ') and for contact with a spring (13').

17. Master cylinder according to one or more of the preceding claims 1 to 16, characterized in that the valve (8 ') has a valve seat (44) which is stationary with respect to the housing (l ¹ ) and which is firmly supported in the bore (7'). . Master cylinder according to claim 17, characterized in that the valve seat (44) is firmly provided on a holding body (45) which can be arranged firmly and pressure-tight in the bore (7'), in particular can be screwed in or pressed in.