Technical field

The present application relates to the field of vehicle braking, in particular to an accumulator for a vehicle braking system, and a vehicle braking system comprising the accumulator.

Background art

A vehicle braking system is generally installed in a vehicle to provide safe braking for the vehicle. The vehicle braking system mainly comprises a master cylinder and a braking circuit. The master cylinder receives brake fluid from a brake fluid reservoir and supplies the brake fluid to the braking circuit, which generates braking pressure by receiving a braking force caused by operation of a brake pedal of the vehicle and amplified by a booster. The braking circuit contains hydraulic elements such as an electromagnetic control valve, an accumulator and a pump, to realize and control braking pressure transferred to hydraulic brakes at the front and rear wheels. An accumulator is an energy storage apparatus in the braking circuit, which fills with brake fluid to store energy in the system or discharges brake fluid to release energy, according to need.

An accumulator in a prior art solution comprises a cylinder, a piston that reciprocates axially in the cylinder, and a coil spring disposed between the piston and a cylinder end cap. Two guide rings which guide the axial motion of the piston are fixed to the piston in an embedded manner close to two ends of the piston, and a sealing member is provided between the two guide rings in such a way as to be fitted round the piston. When the piston moves axially in the cylinder and compresses the coil spring, the guide rings and the sealing member all slide in a reciprocating manner in abutment with an inner surface of the cylinder, wherein cylinder inner surface regions in sliding contact with the guide rings overlap a cylinder inner surface region in sliding contact with the sealing member. While reciprocating, the guide rings of a hard material might cause scratches or other friction defects in the regions of the inner surface of the cylinder in sliding contact therewith, or even cause metal of the inner surface of the cylinder to be exposed, and the exposed part will easily suffer electrochemical corrosion upon coming into contact with brake fluid; at the same time, the sealing member of an elastic material, when moving to and coming into contact with this scratched region, is easily damaged and can no longer effectively seal the outer surface of the piston to the inner surface of the cylinder, with the result that brake fluid at one end of the piston in the cylinder leaks to the other end of the piston, affecting the movement of the piston and in turn affecting the performance of the low-pressure accumulator.

Thus, there is a need to provide an improved technical solution to overcome the technical problems in the prior art.

Summary of the utility model

The object of the present utility model is to solve the problem of poor sealing between a sealing member of an accumulator and a cylinder inner surface scratched by a guide ring.

To this end, according to a first aspect of the present utility model, an accumulator for a vehicle braking system is provided, comprising: a cylinder, having an inner surface defining an internal space, a liquid inlet and a liquid outlet disposed at one end of the cylinder in an axial direction of the internal space, and an end cap disposed at another end of the cylinder; a piston, accommodated in the internal space of the cylinder in such a way as to be capable of reciprocating in the axial direction, the piston having an outer surface opposite the inner surface of the cylinder, a first end close to the liquid inlet and liquid outlet of the cylinder, and a second end opposite the first end and facing the end cap of the cylinder; a sealing member, disposed between the outer surface of the piston and the inner surface of the cylinder (10) in a radial direction of the piston, wherein the sealing member slides past a first axial region of the inner surface of the cylinder in the course of an entire axial stroke of the piston and is in sealing contact with the inner surface of the cylinder; a disc spring device, comprising at least one disc spring, disposed between the piston and the end cap; in the axial direction, one side of the disc spring device abuts the second end of the piston, and another side abuts the end cap, and an outer end edge of the disc spring device is in a clearance fit with the inner surface of the cylinder in the circumferential direction of the disc spring device.

The present application also provides another accumulator, which can be used in a vehicle braking system and comprises: a cylinder, having an inner surface defining an internal space, a liquid inlet and a liquid outlet disposed at one end of the cylinder in an axial direction of the internal space, and an end cap disposed at another end of the cylinder; a piston, accommodated in the internal space of the cylinder in such a way as to be capable of reciprocating in the axial direction, the piston having an outer surface opposite the inner surface of the cylinder, a first end close to the liquid inlet and liquid outlet of the cylinder, and a second end opposite the first end and facing the end cap of the cylinder, wherein a push- in space open toward the end cap is provided at the second end; a sealing member, disposed between the outer surface of the piston and the inner surface of the cylinder (10) in a radial direction of the piston, wherein the sealing member slides past a third axial region of the inner surface of the cylinder in the course of an entire axial stroke of the piston and is in sealing contact with the inner surface of the cylinder; at least one disc spring, disposed between the piston and the end cap, wherein in the axial direction, one side of the disc spring device abuts the end cap; a guiding means corresponding to the push-in space is provided in a protruding manner on a side face of the end cap that faces the piston; the disc spring device is fitted round a peripheral face of the guiding means in such a way as to be axially movable relative to the guiding means and is positioned by the guiding means in a radial direction; in a state in which the disc spring device is not compressed by the piston, the distance between an end of the guiding means that faces the piston and a closed inner end of the push-in space is greater than or equal to the length of the first axial region, and the minimum distance between that side of the disc spring device which faces the piston and the second end of the piston is less than the length of the third axial region.

A second aspect of the present application provides a vehicle braking system comprising either one of the accumulators described above.

According to the present application, the coil spring of the accumulator in the prior art is replaced by the disc spring device and the guide rings are omitted, thus solving the problem of guide rings being in sliding contact with the cylinder inner surface and damaging the inner surface in the prior art, and in turn solving the abovementioned sealing problem.

Brief description of the drawings

A better understanding of the abovementioned and other features of the present utility model will be gained from the following detailed description of embodiments with reference to the drawings. The drawings are not drawn to scale, and are intended only to explain the principles of the present utility model.

Fig. 1 shows a sectional view of part of an accumulator for a vehicle braking system in an embodiment of the present application.

Fig. 2 shows a sectional view of part of an accumulator for a vehicle braking system in another embodiment of the present application.

Fig. 3 shows a sectional view of a disc spring device arranged according to another embodiment of the present application.

Detailed description of the utility model

Fig. 1 shows a feasible embodiment of the present application; the principles of the present utility model are described below with reference to this embodiment. Fig. 1 shows a sectional view of part of an accumulator 100 for a vehicle braking system. Specifically, the figure shows a cylinder 10, having an inner surface defining an internal space, a liquid inlet 11 and a liquid outlet 12 disposed at one end of the cylinder 10 and an end cap 13 disposed at the other end of the cylinder 10 in an axial direction A of the internal space; a piston 20, accommodated in the internal space of the cylinder 10 in such a way as to be capable of reciprocating in the axial direction A, the piston 20 having an outer surface opposite the inner surface of the cylinder 10, a first end 201 close to the liquid inlet 11 and liquid outlet 12 of the cylinder 10, and a second end 202 opposite the first end 201 and facing the cylinder end cap 13; a sealing member 30, disposed between the outer surface of the piston 20 and the inner surface of the cylinder 10 in a radial direction of the piston 20, wherein the sealing member 30 slides past a first axial region of the inner surface of the cylinder 10 in the course of an entire axial stroke of the piston 20 and is in sealing contact with the inner surface of the cylinder 10; and a disc spring device 40, comprising at least one disc spring 41, disposed between the piston 20 and the end cap 13; in the axial direction A, one side of the disc spring device 40 abuts the second end of the piston 20, and another side abuts the end cap 13, and an outer end edge of the disc spring device 40 is in a clearance fit with the inner surface of the cylinder 10 in the circumferential direction of the disc spring device. The “one side” and “other side” of the disc spring device 40 referred to above mean that in the axial direction A, the disc spring device 40 is divided into one side facing the piston 20 and another side facing the end cap 13, according to orientation.

As will be understood, in an embodiment that is not shown, the other side of the disc spring device 40 may also abut a backing plate fixed between the piston 20 and the end cap 13; the backing plate can be regarded as part of the end cap 13, and is still within the scope of protection of the present application. It will also be understood that in the axial direction A, the disc spring device 40 has two end edges, which at the same time may also be an inner end edge and an outer end edge of the disc spring device 40 in a radial direction thereof. In one possible scenario, the disc spring device 40 has an end edge at one side which faces the piston 20 and is closest to an end face of the piston 20, and an end edge at another side which faces the end cap 13 and is closest to the end cap 13, thus the disc spring device 40 is in abutment between end faces of the piston 20 and end cap 13 via the end edges at two sides mentioned above respectively. Alternatively, in another possible scenario, according to the particular design of the piston 20 and/or end cap 13, the disc spring device 40 is in abutment with the piston 20 or end cap 13 via a site (i.e. an abutment site) that is located between two end edges of the disc spring device and close to one of the end edges; in this case, it will further be understood that the abutment site of the disc spring device 40 can be designed according to the shape of an abutment site of the piston 20 or end cap 13 in a corresponding manner, in order to achieve abutment through surface contact as far as possible and avoid the problem of stress concentration at the abutment site. The disc spring device 40 is in a clearance fit with the inner surface of the cylinder 10, and the inner surface of the cylinder 10 can subject the disc spring device 40 to radial positioning and deformation guiding in the axial direction A; deformation of the disc spring device 40 is substantially restricted to the axial direction A, such that the stroke of the piston 20 in the cylinder 10 is also substantially restricted to the axial direction A, and the effect of guiding the piston 20 is thereby achieved. Since there is no need for guide rings to be additionally provided, scratching of the inner surface of the cylinder 10 by guide rings is avoided and the probability of the sealing member 30 being damaged is reduced; at the same time, the number of components in the accumulator is reduced, the process is simplified and the cost is lowered. The disc spring has the characteristics of high rigidity and high capacity for cushioning and vibration absorption, being able to sustain a high load with a small degree of deformation, and compared with the coil spring in a conventional accumulator, can reduce the length of the axial stroke of the piston 20 and sealing member 30, thereby further reducing the probability of the sealing member 30 passing the inner surface of the cylinder 10 that might have been scratched by the outer end edge of the disc spring device 40.

A single-plate disc spring takes the form of a conical disc; according to one embodiment of the present application, the disc spring device 40 comprises multiple disc springs 41 arranged substantially coaxially, with two adjacent said disc springs 41 being arranged parallel to each other and/or symmetrically with respect to each other in the axial direction A. It is thereby possible to adjust a generated spring hardness or spring characteristic curve, and thus possible to further control the length of the entire axial stroke of the piston 20 by adjusting the extent of axial deformation of the disc spring device 40. Fig. 1 shows a scenario in which two adjacent said disc springs 41 are arranged symmetrically with respect to each other in the axial direction A; Fig. 3 shows a scenario in which two adjacent said disc springs 41 are arranged parallel to each other in the axial direction A. As will be understood, when the disc spring device 40 comprises three or more disc springs 41, each pair of adjacent disc springs 41 may be arranged symmetrically or parallel to each other, in a mixed fashion.

In the course of an entire axial stroke of the piston 20, the sealing member 30 slides past a first axial region of the inner surface of the cylinder 10, and the disc spring device 40 slides past a second axial region of the inner surface of the cylinder 10, wherein the minimum value of the distance by which the first axial region and the second axial region are spaced apart in the axial direction is zero. In the first place, due to the fact that the two regions are spaced apart in the axial direction A, the sealing member 30 will not come into contact with the inner surface of the cylinder 10 that might be scratched by the disc spring device 40, so damage to the sealing member 30 is avoided; when the distance by which the first axial region and the second axial region are spaced apart in the axial direction is zero, the required length of the piston 20 is smallest, thus reducing to a certain extent the possibility of the piston 20 becoming jammed in the course of the axial stroke, and also saving material.

As shown in Fig. 1, the piston 20 may comprise a liquid bearing part 21, a connecting part 22 and a pushing part 23 which are arranged sequentially in the axial direction A. Two ends of the connecting part 22 are connected to the liquid bearing part 21 and the pushing part 24 respectively, such that a gap exists between two end faces of the liquid bearing part 21 and the pushing part 23, said two end faces being opposite each other in the axial direction A. An end edge at one side of the disc spring device 40 abuts an end face of the pushing part 23 that faces the end cap 13, and the sealing member 30 is disposed between an outer surface of the liquid bearing part 21 and the inner surface of the cylinder 10 in a radial direction of the piston 20. The connecting part 22 and the pushing part 23 do not necessarily come into contact with the inner surface of the cylinder 10; guiding of the piston 20 can be accomplished by merely guiding the liquid bearing part 21. Thus, it is possible to further rationally reduce the length of the liquid bearing part 21 in the axial direction, thus reducing the possibility of the liquid bearing part 21 becoming jammed in the course of the axial stroke, and at the same time, the precision requirements for the dimensions of the connecting part 22 and the pushing part 23 are reduced, thus reducing process difficulty. Moreover, the gap between the two opposite end faces of the liquid bearing part 21 and the pushing part 23 further opens up the distance between the sealing member 30 and the disc spring device 40, objectively increasing the gap between the first axial region of the inner surface of the cylinder 10 that the sealing member 30 slides past and the second axial region of the inner surface of the cylinder 10 that the disc spring device 40 slides past, and thus avoiding damage to the sealing member 30.

As will be understood, in the embodiment shown in Fig. 1, the size of the pushing part 23 should be sufficient to support and push the disc spring device 40, e.g. the end face of the pushing part 23 that faces the end cap 13 can be round, with a diameter greater than the diameter of an inner end edge (or hollow part) of the disc spring device 40.

Referring to Fig. 1 again, a receiving space 211 facing the end cap 13 is provided at an end of the liquid bearing part 21 that faces the end cap 13, and one end of the connecting part 22 is received in the receiving space 211 in such a way as to be movable relative to an inner surface of the receiving space 211. Optionally, the end of the connecting part 22 that is received in the receiving space 211 has a spherical end face, and the receiving space 211 has a conical inner surface having an opening facing the end cap 13; the spherical end face of the connecting part 22 is in line contact with the conical inner surface of the receiving space 211. Within the axial stroke of the piston 20, when the liquid bearing part 21 is jammed by the inner surface of the cylinder 10, then due to the fact that the connecting part 22 can move relative to the inner surface of the receiving space 211, self-adjustment of the push-in direction of the liquid bearing part 21 can be accomplished by adjusting the pushing direction of the connecting part 22, to eliminate jamming and avoid failure.

As shown in Fig. 1, the receiving space 211 may also be configured to have a conical inner surface having an opening facing the end cap 13, and a straight tubular inner surface that extends toward the end cap 13 from an edge at the opening of the conical inner surface; the spherical end face of the connecting part 22 is in line contact with the conical inner surface of the receiving space 211, and a portion of the connecting part 22 is received in the receiving space. A space defined by the straight tubular inner surface of the receiving space 211 has a certain diameter, objectively causing the pushing direction of the connecting part 22 to deviate from the axial direction A as little as possible, and avoiding excessive adjustment in the process of self-adjustment.

The accumulator 100 also has a venting means for venting the internal space of the cylinder 10. The venting means has a vent hole 51 constructed in the end cap 13 in a penetrating fashion, and a pressure balancing element 52. A receiving means 131, which takes the form of a hollow body and is open toward the piston 20, is provided on a side face of the end cap 14 that faces the piston 20. The pressure balancing element 52 is received in the receiving means 131, and the vent hole 51 is provided at the bottom of the receiving means 131, with the pressure balancing element 52 covering a through-hole cross section of the vent hole 51, and a gaseous and/or liquid medium can pass through the pressure balancing element 52 in the axial direction A. The distance between an end of the receiving means 131 that faces the piston 20 and the end face of the pushing part 23 that faces the end cap 13 is greater than or equal to the length of the first axial region; the disc spring device 40 is fitted round a periphery of the receiving means 131 in such a way as to be axially movable relative to the receiving means 131, and is supported on the end cap 13. The venting means enables bidirectional venting between the internal space of the cylinder 10 and the environment outside the cylinder 10, such that the internal space of the cylinder 10 maintains a sensible pressure, thereby eliminating pressure fluctuation in the cylinder internal space between the piston 20 and the end cap 13, and at the same time also improving and enhancing the sealing effect of the sealing member 30. At the same time, the fact that the distance between the end of the receiving means 131 and the pushing part 23 is greater than or equal to the first axial region ensures that the axial stroke of the piston 20 will not suffer interference from the receiving means 131.

The pressure balancing element 52 may be a porous filter body, preferably made of a foamed and/or a sintered material; for example, it may be made of a plastic material, a metal material and/or a ceramic material at a low cost. Optionally, the vent hole 51 is provided at the bottom of the receiving means 131, with a gap being formed between the vent hole 51 and the pressure balancing element 52 in the axial direction A. The receiving means 141 and/or gap provide a buffer space, and this buffer volume prevents a gaseous and/or a liquid medium that has seeped into the vent hole 51 from loading the pressure balancing element 52 directly; a gaseous and/or a liquid medium located in the buffer space can gradually flow back to the outside of the cylinder through the vent hole 51, such that there is no pressure medium in the buffer space as far as possible.

As shown in Fig. 2, the present application further provides a sectional view of part of another accumulator 200 for a vehicle braking system. Specifically, the figure shows a cylinder 1, having an inner surface defining an internal space, a liquid inlet 101 and a liquid outlet 102 disposed at one end of the cylinder 1 and an end cap 103 disposed at the other end of the cylinder 1 in an axial direction A’ of the internal space; a piston 2, accommodated in the internal space of the cylinder 1 in such a way as to be capable of reciprocating in the axial direction A’, the piston 2 having an outer surface opposite the inner surface of the cylinder 1, a first end 25 close to the liquid inlet 101 and liquid outlet 102 of the cylinder, and a second end 26 opposite the first end 25 and facing the cylinder end cap 103, wherein a push-in space 27 open toward the end cap 103 is provided at the second end 26; a sealing member 3, disposed between the outer surface of the piston 2 and the inner surface of the cylinder 1 in a radial direction of the piston 2, wherein the sealing member 3 slides past a third axial region of the inner surface of the cylinder 1 in the course of an entire axial stroke of the piston 2 and is in sealing contact with the inner surface of the cylinder 1; and a disc spring device 4, comprising at least one disc spring 401, disposed between the piston 2 and the end cap 103, wherein in the axial direction A’, one side of the disc spring device 4 abuts the end cap 103. A guiding means 104 corresponding to the push-in space 27 is provided in a protruding manner on a side face of the end cap 103 that faces the piston 2; the disc spring device 4 is fitted round a periphery of the guiding means 104 in such a way as to be axially movable relative to the guiding means 104, and an inner end edge of the disc spring device 4 is in a clearance fit with a peripheral face of the guiding means 104 in the circumferential direction of the disc spring device, such that the disc spring device 4 can be positioned radially by the guiding means 104 while being compressed axially.

In a state in which the disc spring device 4 is not compressed by the piston 2, the distance between an end of the guiding means 104 that faces the piston 2 and a closed inner end of the push-in space 27 is greater than or equal to the length of the third axial region, thus ensuring that the axial stroke of the piston 2 will not suffer interference from the guiding means 27. The minimum distance between that side of the disc spring device 4 which faces the piston 2 and the second end 26 of the piston 2 is less than the length of the third axial region, thus ensuring that the piston 2 can effectively compress the disc spring device 4, to realize the function of the accumulator.

In the same manner as described above, in the embodiment shown in Fig. 2, the disc spring device 4 may abut the end cap 103 via an end edge at one side thereof that faces the end cap 103; alternatively, depending on the particular design, it is also possible for the disc spring device 4 to abut the end cap 103 via a site (an abutment site) close to the end edge, wherein the structure of the abutment site can be designed adaptively so as to abut the end cap 103 by surface contact. Similarly, in the process of the disc spring device 4 being compressed, that side of the disc spring device 4 which faces the piston 2 might also be in abutment in a manner similar to that described above, which will not be described again.

In contrast to the “external guiding” of the disc spring device through the clearance fit between the inner surface of the cylinder and an outside edge of the disc spring device in the embodiment of the accumulator shown in Fig. 1, in the embodiment of the accumulator 200 shown in Fig. 2 the disc spring device 4 is “internally guided” by passing the guiding means 104 through a hollow region of the disc spring device 4, in which case the outside edge of the disc spring device 4 does not necessarily come into contact with the inner surface of the cylinder 1. This not only prevents the inner surface of the cylinder 1 from being scratched and possibly damaging the sealing member 3, but also enables the use of a disc spring of smaller size, thus lowering costs. Furthermore, in this embodiment, a peripheral surface of the guiding means 104 may also be subjected to a smoothing treatment, so that the disc spring device 4 fitted round the periphery of the guiding means 104 has a smoother stroke in the axial direction.

As will be understood, the end cap 103 of the accumulator 200 in the embodiment shown in Fig. 2 is also provided with a vent hole, for the purpose of realizing the function of balancing pressure by venting. Optionally, the guiding means 104 can be fixed to the end cap 103 by means of a partition plate that is separated from the bottom of the end cap 103 by an axial distance, with vent holes being provided in the bottom of the end cap 103 and the partition plate to achieve venting; or optionally, the guiding means 104 is fixed directly to the bottom of the end cap 103, and a venting channel runs through the bottom of the end cap 103 and the guiding means 104, to achieve venting between the spaces inside and outside the cylinder 1 so as to balance pressure.

The present application also provides a vehicle braking system, comprising the accumulator described above.

Multiple embodiments of the present utility model have been described above with reference to the drawings. Those skilled in the art will understand that the scope of protection of the present application is not limited to the embodiments described above and shown in the drawings; on the contrary, features disclosed in different embodiments may be recombined to form new embodiments, without deviating from the basic principles of the present application. The scope of protection of the present application is defined by the claims alone.