DE10232384A1 - piston pump - Google Patents

Abstract

A piston pump having a housing that defines a compression chamber, a piston slidably received in the housing and exposed to the compression chamber at one end, a drive cam for reciprocating the piston, a discharge valve connected to the compression chamber , an intake valve connected to the compression chamber, and a low pressure accumulator for receiving fluid of a predetermined pressure or more connected to the compression chamber through the intake valve. Even when the intake valve is in a closed position, a small amount of the fluid is discharged from the compression chamber to the low pressure accumulator side through a slit formed on the intake valve. The small amount of fluid that is discharged through the slit is received in a receiving space at a small pressure.

Description

FIELD OF THE INVENTION

This invention relates to a piston pump. In particular, the invention relates to a piston pump directed, such as B. for a Hydraulic brake pressure control device of a vehicle suitable is.

BACKGROUND OF THE INVENTION

Youngest vehicles are equipped with devices to run various controls or regulations equipped, such as an anti-lock braking system, a traction control and one Longitudinal braking force distribution control. On Hydraulic pressure control device used for such controls used has a piston pump. The Japanese For example, laid-open publication No. H08-40234 a piston pump designed for a hydraulic brake pressure device a vehicle is provided. In connection with one Evacuation procedure used in this publication is disclosed in which air from a master cylinder memory is evacuated before brake fluid to the Hydraulic brake pressure device of the vehicle is guided a slot on a seat portion of an exhaust valve for evacuation as a device for solving a Problem formed that the brake fluid is not in a Pump chamber (compression chamber) of the piston pump filled can be. The evacuation slot can also be opened the seat portion of an intake valve corresponding to the Be trained for publication.

In such a known piston pump disclosed in the above publication, noise is generated, particularly in an output mode of the pump, and must be reduced accordingly. Fig. 28 to 30 show an operating state of the known piston pump for explaining a situation that the noise is generated. The pump has one-way valves for an inlet (inlet valve) IV and for an outlet (outlet valve) OV. These valves are generally provided with a spherical valve portion and a spring for biasing the spherical valve portion. A piston PR is reciprocated by a drive device having a drive cam DR that is driven by an electric motor (not shown). The volume of a compression chamber CP is reduced or expanded accordingly. The output side of the pump is connected to a damping chamber DP, the inlet side of the pump is connected to a normally closed electromagnetic valve NC, which acts like such an actuator in the hydraulic brake pressure device disclosed in the above publication, and is connected to a low-pressure accumulator RS. As explained below, the noise is generated especially when the inlet side of the pump is in a closed state. In Fig. 28 to 30 is, therefore, the electromagnetic valve NC in a closed position, wherein the low-pressure accumulator RS in a deflated state as it is without any fluid (brake fluid).

FIG. 28 shows a last output mode of the pump (dead center of the piston PR), in which the inlet valve IV is in the closed position and the volume of the compression chamber CP is reduced to a minimum volume Q. The outlet valve OV is in an open position, a gap being formed between the spherical valve section and the seat section. Therefore, the brake fluid is discharged from the compression chamber CP into the damping chamber DP through the gap formed on the exhaust valve OV. When the mode is changed from the top dead center to the bottom dead center of the piston PR by rotating the drive cam DR as shown by an arrow in Fig. 28, the volume of the compression chamber CP is expanded with the intake valve IV still in the closed position , If the exhaust valve OV is closed immediately at this stage, only the pressure in the compression chamber CP is reduced at the minimum volume Q of the brake fluid in the compression chamber CP. However, it takes time for the ball-like valve portion of the exhaust valve OV to sit on the seat portion, so that a volume ΔQ1 of the brake fluid flows from the damping chamber DP into the compression chamber CP. The brake fluid in the compression chamber CP in FIG. 29 is therefore increased to a volume Q + ΔQ1.

When the drive cam continues DR as shown in Fig. 29 by the arrow, the condition shown 29 is rotated by the in FIG., The drive cam DR to the top dead center of the piston proceeds PR above, as shown in Fig. 30 are shown. Under this condition, the brake fluid is compressed in the compression chamber CP (Q + ΔQ1). At this time, since the exhaust valve OV is in the closed position, the pressure in the compression chamber CP is increased to a pressure slightly exceeding a pressure Pd in the damping chamber DP, as shown by a broken two-dot chain line at point (c) in Fig . 31 is shown. The increased pressure is transmitted to the drive cam DR through the piston PR, which results in a reason for the noise at the engine section (not shown). Points (a) and (b) in Fig. 31 show the pressure in the compression chamber CP under the conditions of Figs. 28 and 29, respectively.

In this case, when the slit is formed on the seat portion of the intake valve for evacuation as applied in the pump disclosed in the above publication, a volume ΔQ2 (approximately equal to ΔQ1) of the brake fluid is discharged from the compression chamber CP through the slit. However, the inlet side of the pump is a closed hydraulic pressure channel, as mentioned above, wherein the pressure in the pressure chamber CP is increased until it approximates the pressure in the damping chamber DP. As shown in Fig. 28, a resin seal member SL is provided on the piston PR. Since the sealing element SL does not work as an ideal seal, a small gap is provided on it. In the same way as in the above slot, however, the inlet side of the pump is the closed hydraulic pressure passage, so that the pressure in the compression chamber CP cannot be increased. In addition, since the gap is made uneven or irregular, the sealing member SL cannot be used as a communicating hole for measures against the occurrence of the noise without a special arrangement.

SUMMARY OF THE INVENTION

It is an object of the present invention Piston pump with a simple structure, the one Can reduce noise caused by operation of a Exhaust valve is caused. It's another job the present invention to provide a piston pump in the one inlet side with a low pressure accumulator connected is. It is another object of the present Invention to provide a piston pump, not only for a hydraulic brake pressure device of a vehicle but also applicable to a wide range of hydraulic equipment is.

According to one aspect of the present invention the piston pump has a housing, the one Compression chamber defines a piston that slides in the housing is received and to the compression chamber is exposed at one end, a drive device for Reciprocating the piston, an exhaust valve that with the compression chamber is connected, an inlet valve, connected to the compression chamber, and one Low pressure accumulator for holding fluid in one predetermined pressure or more with the damping chamber is connected through the inlet valve. The piston pump has and an issuing device for permitting a small amount of the fluid that it is from the Compression chamber in the low pressure storage side is issued even if the intake valve is in a closed position, and a receiving device, which has a recording room to hold the small amount of Fluids, the device permitting the issue is released, and for receiving the fluid at a small pressure that is less than the specified pressure.

In the piston pump mentioned above, this is Inlet valve provided with a valve seat, being a Valve section is always biased to on the Valve seat to sit. A slot is at least either formed on the valve portion or the valve seat to preferably to arrange the device permitting the dispensing. The facility allowing this issue will make the small one Amount of fluid from the compression chamber to the Low-pressure storage page output even if that Inlet valve is in the closed position.

The piston is slidable in the housing by a Sealing element to be added to the small amount of Allow fluids to be emitted from the compression chamber to become. The facility permitting the dispensing can by the sealing element may be formed.

The low pressure accumulator is preferably one Cylinder that connects with the compression chamber through the Inlet valve is connected to a piston which is slidable in the cylinder is received and a fluid chamber for Receiving the fluid in the cylinder forms, and one Biasing device for biasing the piston into a Direction in which the volume of the fluid chamber decreases is provided.

The piston in the present invention is made with a concave section formed by a Membrane element on a surface of the piston that leads to the Fluid chamber is exposed, is covered. The recording room the receiving device is preferably by a expanded space formed in the fluid chamber is formed when the membrane element within the concave portion is deformed. The membrane element can be formed integrally with the piston.

An annular groove can be on an outer circumference of the Be formed piston, an annular elastic element inserted into the annular groove can be converted into a given space in between Form the sliding direction of the piston. The recording room of the Reception facility can be through an expanded room be formed between the annular elastic Element and the annular groove is formed when that annular elastic element is deformed.

A reverse biasing device is provided around the Piston in an opposite direction to one Biasing force of the above biasing device pretension. The receiving space of the receiving device is through an expanded space in the fluid chamber formed by adjusting the biasing force of the Reverse biasing device relative to that of the Preload device is expanded. The Reverse biasing device in the present invention preferably an elastic element between the Piston and the cylinder is arranged. As the elastic Element is e.g. B. a conical disc spring, a Coil spring and an elastic resin ring available.

The receiving device can be equipped with a lower cylinder, the one on the piston for communicating with the fluid chamber is formed, a lower piston which is slidable in the Lower cylinder is received and a sub-fluid chamber for Receiving fluid in the sub-cylinder forms, and a sub-biasing device for biasing the Lower piston in a direction in which the volume of the Lower fluid chamber is reduced, may be provided.

The receiving device can with the lower cylinder, on the housing for communicating with the fluid chamber is formed, the lower piston, which is slidable in the Lower cylinder is received and the sub-fluid chamber for Receiving fluid in the sub-cylinder forms, and the sub-biasing device for biasing the Lower piston in the direction in which the volume of the Lower fluid chamber is reduced, may be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and Properties of the present invention will be better known in conjunction with the detailed description below taken with the accompanying drawings, in where the same reference numbers designate the same elements, and in which:

Fig. 1 is a cross-sectional view of a piston pump according to a first embodiment of the present invention;

Fig. 2 is a cross-sectional view of the piston pump according to a second embodiment of the present invention;

Fig. 3 is a part of the piston pump is an enlarged cross-sectional view according to another embodiment of the present invention;

Fig. 4 is a cross-sectional view of a first embodiment of a low-pressure accumulator is used in the present invention;

Figure 5 is a cross-sectional view showing a part of an operating state of the first embodiment of the low-pressure accumulator.

Figure 6 is a cross-sectional view of a second embodiment of the low-pressure accumulator, which is used in the present invention.

Fig. 7 is a cross-sectional view showing a part of an operating state of the second embodiment of the low-pressure accumulator;

Fig. 8 is a cross-sectional view of a third embodiment is of the low-pressure accumulator, which is used in the present invention;

Fig. 9 is a cross-sectional view showing a part of an operating state of the third embodiment of the low-pressure accumulator;

Fig. 10 is a partially enlarged cross-sectional view of Fig. 9;

11 is a cross-sectional view of a fourth embodiment Fig of the low-pressure accumulator, which is used in the present invention.

Fig. 12 is a cross sectional view showing part of an operating state of the fourth embodiment of the low pressure accumulator;

Fig. 13 is a partially enlarged cross-sectional view of Fig. 12;

Fig. 14 is a cross sectional view of a fifth embodiment of the low pressure accumulator used in the present invention;

Fig. 15 is a cross sectional view showing part of an operating state of the fifth embodiment of the low pressure accumulator;

FIG. 16 is a cross-sectional view of a sixth embodiment is of the low-pressure accumulator, which is used in the present invention;

Fig. 17 is a cross sectional view showing part of an operating state of the sixth embodiment of the low pressure accumulator;

FIG. 18 is a cross-sectional view of a seventh embodiment is the low-pressure accumulator, which is used in the present invention;

Figure 19 is a cross-sectional view showing a part of an operating state of the seventh embodiment of the low-pressure accumulator.

FIG. 20 is a cross-sectional view of an eighth embodiment is the low-pressure accumulator, which is used in the present invention;

Fig. 21 is a cross sectional view showing part of an operating state of the eighth embodiment of the low pressure accumulator;

Figure 22 is a cross-sectional view of a ninth embodiment of the low-pressure accumulator, which is used in the present invention.

FIG. 23 is a cross-sectional view showing a part of an operating state of the ninth embodiment of the low-pressure accumulator;

FIG. 24 is a cross-sectional view of a tenth embodiment is the low-pressure accumulator, which is used in the present invention;

Fig. 25 is a cross sectional view showing part of an operating state of the tenth embodiment of the low pressure accumulator;

Figure 26 is a diagram showing a relationship between a pressure in a fluid chamber of the low-pressure reservoir and a stroke is a plunger according to some embodiments of the low-pressure accumulator, which is used in the present invention.

Figure 27 is a diagram showing a relationship between the pressure in the fluid chamber of the low-pressure accumulator and the hub showing the piston according to the remaining embodiments of the low-pressure accumulator, which is used in the present invention.

FIG. 28 is an explanatory view of an operation state is a known piston pump, in particular, a state is shown, when a piston at a top dead center;

Figure 29 is an explanatory view of an operating state of a known piston pump, in particular, is shown the state when the piston from the upper dead center is moved to a bottom dead center.

. 30 is an explanatory view of an operating state of Fig known piston pump, in particular, is shown the state when the piston is moved to a next top dead center;

31 is Fig. A diagram illustrating a printing state in a compression chamber in accordance with the piston position in accordance with the general piston pump and the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to embodiments of the present invention with reference to the accompanying drawings, Fig. 1 shows a first embodiment of a piston pump of this invention. A damping chamber DP and a compression chamber CP are defined in a housing 1 , in which holes 1 a and 1 b, which are connected to the compression chamber CP, are formed. A piston 2 is slidably received in the hole 1 a, which is exposed to the compression chamber CP at one end.

The piston 2 of the present embodiment has a roller shape and has an annular groove 21 at a center in which a sealing element S1 is arranged. The piston 2 is slidably moved within the hole 1 a under the condition that a front and a back of the sealing portion S1 is hydraulically sealed. As a driving means for driving the piston 2, to move back and forth, a drive cam 4 is provided (not shown) by an electric motor relative to a shaft 3 which is perpendicular to an axis of the hole 1a, rotated becomes. By a coil spring 5 , which is arranged between a seat element 6 a, which will be mentioned later, and the piston 2 , the piston 2 is biased to be pressed into contact with a circumferential cam surface of the drive cam 4 . One end side of the piston 2 is in contact with the drive cam 4 at atmospheric pressure. Since the drive cam 4 is in relation to the shaft 3 which is disposed in an eccentric position to the center of the drive cam 4 is rotated accordingly, the piston 2 which is in contact with the cam peripheral surface in the hole 1 a back and moved here. In this exemplary embodiment of the present invention, the piston 2 is moved back and forth once per revolution of the drive cam 4 .

The compression chamber CP is connected to an exhaust valve 6 and an intake valve 7 through the hole 1 b. The discharge valve 6 of this embodiment, which forms a one way valve is connected to the seat member 6a, which is fitted to the compression chamber CP, a ball-like valve portion 6b, which is settable to a valve seat a of the seat member 6 a formed outlet hole 6 e is provided, a coil spring 6 c, which biases the ball-like valve section 6 b in a direction of the seat, and a holder 6 d is provided, which is coupled to the seat element 6 a for holding the coil spring 6 c. In the same way, the inlet valve 7 of this embodiment, which forms the one-way valve, with a seat element 7 a, which is passable to the hole 1 b, which is connected to the compression chamber CP, a spherical valve section 7 b, which can be placed on the valve seat around said, is fixed to the seat element 7 a formed inlet hole 7e provided a coil spring 7c that the ball-like valve portion 7 b in the direction of the seat biases, and a holder 7 provided d, of the seat member 7 a for holding the coil spring 7 c is coupled.

On the valve seat around the inlet hole 7 e, on which the spherical valve section 7 b is placed, a narrow slot 7 s is formed. Therefore, even when the intake valve 7 is in a closed position as the ball-like valve portion 7 b 7 e is set on the valve seat around the inlet hole, output a small amount of fluid from the compression chamber CP to one side of a low-pressure accumulator 10 degrees. Therefore, an output permitting device of the present invention is formed through the slit 7s according to the first embodiment.

The low pressure accumulator 10 is connected to the above-mentioned intake valve 7 and is therefore connected to the compression chamber CP through the intake valve 7 . The low-pressure accumulator 10 of this exemplary embodiment is designed in the same way as that of FIGS. 4, 5 and can absorb the fluid at a predetermined pressure or more. That is, a piston 11 is slidably received in a cylinder 10 a, which is connected to the compression chamber CP through at least the inlet valve 7 . A fluid chamber CF is formed between an upper surface of the piston 11 and an inner wall of the cylinder 10 a. The fluid chamber CF and the cylinder 10 a, which is provided on the other side with respect to the piston 11 , are hydraulically separated by a sealing element S2, which is provided on an outer circumference of the piston 11 . A coil spring 12 is provided as a biasing means for biasing the piston 11 in a direction in which the volume of the fluid chamber CF is reduced. Therefore, the fluid having the predetermined pressure or more that overcomes the biasing force of the coil spring 12 is received in the fluid chamber CF. A plate 13 with a hole 13 a in the middle is an element for holding the coil spring 12 . One side of the coil spring 12 of the plate 13 within the cylinder 10 a is connected to the environment (atmosphere) through the hole 13 a.

In the low pressure accumulator 10 of this embodiment, a stepped concave portion, which has concave portions 11 a and 11 b, is formed on the upper surface of the piston 11 , which is exposed to the fluid chamber CF. A membrane element 14 is provided on the stepped section, so that the concave section 11 b is covered, and is fastened by an annular element 15 . A bottom surface of the concave portion 11 is formed with a communicating hole c 11 b. Accordingly, a space is formed between the membrane element 14 and the concave portion 11 b. A receiving space of this invention is formed by an expanded space that is formed by the membrane member 14 that is deformed within the concave portion 11 b. At this time, since the space between the membrane member 14 and the concave portion 11b with the atmosphere through the communicating hole 11 c is connected to the membrane element 14 within the concave portion 11 b by the fluid in the fluid chamber CF with a small pressure, which is less than the predetermined pressure, flows connected. Therefore, in the expanded space formed on the upper surface of the membrane member 14 , the fluid is absorbed at the low pressure.

The operation of the piston pump of the present invention will be explained below. The piston 2 is moved back and forth in the hole 1 a by the drive cam 4 , which is rotated with respect to the shaft. The piston 2 is moved to the right in FIG. 1, the volume of the compression chamber CP then being expanded. When the inlet valve is opened (the outlet valve 6 is closed), the fluid (for example brake fluid) is fed from the fluid chamber CF of the low-pressure accumulator 10 to the compression chamber CP through the inlet hole 7 e of the inlet valve 7 . When the piston 2 is moved to the left of FIG. 1, the volume of the compression chamber CP is reduced, and the intake valve 7 is closed. At the same time, the exhaust valve 6 is opened, and the fluid in the compression chamber CP flows to the damper chamber DP.

In the above operation, when the piston 2 is moved from the top dead center (left end position) to the right, a small amount of the fluid (brake fluid) flows into the compression chamber CP until the spherical valve portion 6 b of the exhaust valve 6 is seated on the seat member 6 a , The excess fluid flows to the low pressure accumulator 10 side through the slit 7s formed in the intake valve 7 even when the intake valve 7 is in the closed position. The fluid that is discharged through the slit 7 s flows into the fluid chamber CF of the low-pressure accumulator 10 and is received in the expanded space formed on the upper surface of the diaphragm member 14 that is deformed within the concave portion 11 b. Accordingly, the pressure in the compression chamber CP is not excessively increased as shown by a solid line in FIG. 31, and the occurrence of the noise by the piston 2 can be prevented.

Fig. 2 shows the second embodiment of the piston pump. Instead of the piston 2 and the inlet valve 7 in FIG. 1, a piston 20 and an inlet valve 70 are used. The low pressure accumulator 10 is connected to the compression chamber CP through the piston 20 and the inlet valve 70 . In the second embodiment, a hole 1 c, which connects the compression chamber CP and the damper chamber DP, is provided. An exhaust valve 60 is fitted to the hole c. 1 The compression chamber CP is defined by a piston element 8 which is attached to the housing 1 , the inlet valve 70 being accommodated in the compression chamber CP.

As shown in FIG. 2, the piston 20 of the second embodiment is formed with an annular groove 21 , a hole 22 in the axial opening direction in the compression chamber CP, a communicating hole 23 connecting the annular groove 21 and the hole 22 . An annular sealing member S3 is provided on the compression chamber CP side, and an annular sealing member S4 is provided on the drive cam 4 side relative to the annular groove 21 . A fluid chamber CG formed by the annular groove 21 and the housing 1 are connected by the fluid chamber CF (not shown in FIG. 2) of the low-pressure accumulator 10 , as shown by a chain line in FIG. 2. The sealing member S4 on the drive cam 4 side acts as an ideal seal because it is made of rubber, but the sealing member S3 on the compression chamber CP side does not act as an ideal seal because it is made of a resin. Therefore, a small amount of fluid is discharged from the compression chamber CP through the sealing member S3. As shown in more detail in FIG. 3, the upper drawing shows a state of an initial position of the sealing member S3. In Fig. 3, the resin sealing member S3 is inserted into the annular groove 24 of the piston 20 , so that a small space is formed therebetween. The lower drawing in FIG. 3 shows a compressed state of the sealing element S3 in which a hydraulic channel is formed between the annular groove 24 and the sealing element S3 in order to allow the small amount of the fluid to flow out of the compression chamber CP. Accordingly, the output-permitting device of the present invention is formed by the sealing member S3 according to the second embodiment.

As the structure of the low pressure accumulator connected to the compression chamber CP through the intake valve 7 or the intake valve 70 and the piston 20 as shown in Figs. 1, 2, not only the low pressure accumulator 10 shown in Fig. 1 can be but also various types of low pressure accumulators, as explained below, can be used. Fig. 4, 5 show the low-pressure accumulator is used in the invention of the first embodiment. The low-pressure accumulators in FIGS. 4, 5 are the same as those in FIG. 1, so that their explanation is not repeated here. FIG. 4 shows the state before the low-pressure accumulator is operated as a receiving device, and FIG. 5 shows the state when the low-pressure accumulator acts as a receiving device. When the fluid flows into the fluid chamber CF, the membrane element 14 is deformed within the concave portion 11 b. The fluid is received in the expanded space formed on the membrane element 14 as shown in FIG. 5. The accommodating space in the present invention is constructed by the expanded space that is thus formed.

The fluid in the expanded space, which is formed on the concave portion 11 b in the membrane element 14 , is absorbed under the small pressure by an elastic deformation of the membrane element 14 . The relationship between the stroke of the piston 11 and the pressure in the fluid chamber CF of the low-pressure accumulator 10 is shown in FIG. 26 by a solid line, which shows that the stroke of the piston 10 cannot be achieved until the pressure of the low-pressure accumulator reaches a predetermined pressure (Pb) or more reached. In the first embodiment of the low pressure accumulator, however, as shown by a chain line in Fig. 26, the small stroke (Da) of the piston 11 is achieved by a small pressure (Pa) that is less than the predetermined pressure (Pb). The fluid with the low pressure (Pa) is absorbed by the action of the receiving device (membrane element 14 and concave section 11 b) on the pressure in the fluid chamber CF. When the pressure on the side of the fluid chamber CF is reduced, the fluid returns to the expanded space of the concave portion 11 b in the membrane element 14 to the fluid chamber CF by the elastic force of the membrane element 14 back.

Fig. 6, 7 show the second embodiment of the low-pressure accumulator, which is used in the present invention. FIG. 6 shows the state before the low-pressure accumulator is operated as a receiving device, and FIG. 7 shows the state when the low-pressure accumulator works as a receiving device. In the second exemplary embodiment, the membrane element 14 is formed integrally with the piston 11 . For example, when the piston 11 is molded from a resin, the membrane member 14 is molded from the elastic resin material integrally with the piston 11 . Therefore, the annular member 15 of the first embodiment in Figs. 4, 5 is not required, so that the number of parts is reduced and the manufacturing process is shortened. Since the rest of the structure of the second embodiment of the low pressure accumulator used in the present invention is substantially the same as that of the embodiment in Figs. 4, 5, the substantially same parts or components shown in Fig. 4, 5, the same numbers are shown in the second embodiment.

Fig. 8, 9 show the third embodiment of the low-pressure accumulator, which is used in the present invention. FIG. 8 shows the state before the low-pressure accumulator is operated as a receiving device, and FIG. 9 shows the state when the low-pressure accumulator works as the receiving device. Fig. 10 is an enlarged view of part of Fig. 9, in which the hatching of a sealing member S5 is omitted for easy understanding. In the third embodiment, the sealing member S5, which is inserted into an annular groove 16 formed on an outer periphery of the piston 11 , is formed in a shape different from the sealing member S2 of the above first embodiment. A predetermined space is formed between the sealing element S5 and the annular groove 16 . The sealing element S5, which is the annular elastic element of the present invention, has an approximately X-shaped cross section and is designed to form the predetermined space between the annular groove 16 , which has an almost rectangular cross section, when inserted therein , Since the remaining structure of the third embodiment of the low pressure accumulator used in the present invention is substantially the same as that of the embodiment in FIGS. 4, 5, parts or components substantially the same as those in FIGS. 4, 5 are shown, the same numbers in the third embodiment, the explanation is not repeated here.

As shown in FIG. 9, when the fluid flows into the fluid chamber CF, the sealing member S5 is pushed to one side of the annular groove 16 (lower side in FIG. 9) by the small pressure of the fluid. At the same time, a portion of the sealing member S5 in contact with the annular groove 16 is deformed so that it closely contacts an inner surface of the annular groove 16 .

Accordingly, an expanded space CL is formed as shown in FIG. 10, and the accommodating space of this invention is thereby formed. The fluid flows into the space formed within the annular groove 16 , which includes the expanded space CL, and is absorbed under the small pressure by the elastic deformation of the sealing member S5. That is, as shown by the broken line in Fig. 26, that the small stroke (Da) of the piston 11 is achieved by the small pressure (Pa) which is less than the predetermined pressure (Pb). The fluid under the low pressure (Pa) is absorbed by the action of the receiving device (sealing element S5 and annular groove 16 ) on the pressure in the fluid chamber CF. When the pressure on the fluid chamber CF side is reduced, the fluid returns to the fluid chamber CF in the expanded space CL by the elastic force of the sealing member S5. In the third embodiment of the low pressure accumulator used in the present invention, since its structure is the same as that of the first and second embodiment of the low pressure accumulator and only the sealing member S5 needs to be provided, the manufacture is easy.

Fig. 11, 12 show the fourth embodiment of the low-pressure accumulator, which is used in the present invention. FIG. 11 shows the state before the low-pressure accumulator is operated as the receiving device, and FIG. 12 shows the state when the low-pressure accumulator works as the receiving device. Fig. 13 is an enlarged view of a part of Fig. 12, in which the hatching of a sealing member S7 is omitted for easy understanding. In the fourth embodiment, the accommodating space of the present invention is formed by the expanded space (shown as CL in FIG. 13) formed between the sealing member S6 and the annular groove 16 in the same manner as in the embodiment in FIGS. 8, 9 , educated. However, the expanded space CL is designed in a different form from the sealing element S5 of the exemplary embodiment in FIGS. 8, 9. The sealing member S6, which constitutes the elastic member of this invention, has an approximately U-shaped cross section and is designed to form a predetermined space between the annular groove 16 , which has an approximately rectangular cross section, when inserted thereon.

As shown in FIG. 12, when the fluid flows into the fluid chamber CF, the sealing member S6 is pressed to one side of the annular groove 16 (lower side in FIG. 12) by the small pressure of the fluid. At the same time, a portion of the sealing member S6 in contact with the annular groove 16 is deformed so that it closely contacts the inner surface of the annular groove 16 . The fluid in the annular groove 16 , which has the expanded space CL, which is formed by the above-mentioned manner, is received under the small pressure by the elastic deformation of the sealing member S6. As shown by the chain line in Fig. 26, the small stroke (Da) of the piston 11 is achieved by the small pressure (Pa), whereby the fluid is absorbed at the small pressure (Pa). Since the rest of the structure of the fourth embodiment of the low pressure accumulator used in the present invention is substantially the same as that of the embodiment in Figs. 8, 9, the substantially same parts or components shown in Fig. 8, 9, the same numbers in the third embodiment, the explanation not being repeated here. In the fourth exemplary embodiment as well, since only the sealing element S6 has to be provided, production is simple.

Fig. 14, 15 show the fifth embodiment of the low-pressure accumulator, which is used in the present invention. FIG. 14 shows the state before the low-pressure accumulator is operated as a receiving device, FIG. 15 shows the state when the low-pressure accumulator works as a receiving device. In the fifth embodiment, an elastic member is arranged as a reverse biasing device between the piston 11 and the cylinder 10 a for biasing the piston 11 in a reverse direction to a biasing direction of the coil spring 12 . Furthermore, in the fifth embodiment, a conical disc spring 17 is used as the elastic member. The receiving space of the present invention is formed by an expanded space that is formed when the volume of the fluid chamber CF is expanded by adjusting the biasing force of the conical disc spring 17 with respect to that of the coil spring 12 .

In a non-working state of the receiving device, as shown in Fig. 14, a space, which is formed between the inner surface of the piston 11 and that of the cylinder 10 a, by the biasing force of the conical disc spring 17 relative to that of the coil spring 12 D1 set. When the small pressure of the fluid flowing into the fluid chamber CF is added, the volume of the fluid chamber CF is expanded, changing the clearance to D2 as shown in FIG. 15. Then the fluid is absorbed under the small pressure by the biasing force of the conical disc springs 17 relative to that of the coil spring 12 . A relationship between the stroke of the piston 11 and the pressure in the fluid chamber CF of the low pressure accumulator 10 is as shown in FIG. 27, which shows that a small stroke (Db) of the piston 11 is achieved by the small pressure (Pa) that is less than the predetermined pressure (Pb), the fluid being absorbed at the low pressure (Pa). In the fifth embodiment, since the structure of the piston 11 is the same as that of the above-mentioned embodiments of the low pressure accumulator, with only one space for accommodating the conical disc spring 17 , the manufacture is simple. The remaining structure of the fifth embodiment of the low pressure accumulator used in the present invention is substantially the same as that of the embodiment in FIGS. 4, 5, so that substantially the same parts or components as in FIGS. 4, 5 are shown bearing the same numbers in the fifth embodiment, the explanation not being repeated here.

Fig. 16, 17 show the sixth embodiment of the low-pressure accumulator, which is used in the present invention. FIG. 16 shows the state before the low-pressure accumulator is operated as the receiving device, and FIG. 17 shows the state when the low-pressure accumulator works as the receiving device. Also, in the sixth embodiment, the elastic member when the reverse biasing means between the piston 11 and the cylinder 10 is disposed for biasing the piston in a reverse direction to the biasing direction of the coil spring 12th Furthermore, in the sixth embodiment, a coil spring 18 is used as the elastic member. The receiving space of the present invention is formed by an expanded space that is formed when the volume of the fluid chamber CF is expanded by adjusting the biasing force of the coil spring 18 relative to that of the coil spring 12 .

In the non-working state of the receiving device, as shown in Fig. 16, a space, which is formed between the inner surface of the piston 11 and that of the cylinder 10 a, is set to D3 by the biasing force of the coil spring 18 relative to that of the coil spring 12 , When the small pressure of the fluid flowing into the fluid chamber CF is added, the volume of the fluid chamber CF is expanded, changing the clearance to D4 as shown in FIG. 17. Then, the fluid is taken up under the small pressure by the biasing force of the coil spring 18 relative to that of the coil spring 12 . In the sixth embodiment, in the same way, the relationship between the stroke of the piston 11 and the pressure in the fluid chamber CF of the low-pressure accumulator 10 is shown, as shown in FIG. 27, that the fluid with the low pressure (Pa) is taken up. Furthermore, in the sixth embodiment, the structure of the piston 11 is the same as that of the above-mentioned embodiments of the low pressure accumulator, so that the coil spring 18 can be used, the biasing force of which is easily adjustable as the reverse biasing device. However, an enlarged diameter portion 1d must be formed in a position opposite to the piston 11 and connected to the fluid chamber CF to receive the coil spring 18 . Since the rest of the arrangement of the sixth embodiment of the low pressure accumulator used in the present invention is substantially the same as that of the embodiment in Figs. 4, 5, the substantially same parts or components as in Figs. 5, the same numbers in the sixth embodiment, the explanation is not repeated here.

Fig. 18, 19 show the seventh embodiment of the low-pressure accumulator, which is used in the present invention. FIG. 18 shows the state before the low-pressure accumulator is operated as the receiving device, and FIG. 19 shows the state when the low-pressure accumulator operates as the receiving device. Further, in the seventh embodiment, the elastic member when the reverse biasing means between the piston 11 and the cylinder 10 a arranged for biasing the piston 11 in the opposite direction to the biasing direction of the coil spring 12th Furthermore, in the sixth embodiment, an elastic resin ring is used as the elastic member. The receiving space of the present invention is formed by an expanded space that is formed when the volume of the fluid chamber CF is expanded by adjusting the biasing force of the elastic resin ring relative to that of the coil spring 12 .

In the non-working state of the receiving device, as shown in Fig. 18, a space which is formed between the inner surface of the piston 11 and that of the cylinder 10 a, by the biasing force of the elastic resin ring 19 relative to that of the coil spring 12 D5 set. When the small pressure of the fluid flowing into the fluid chamber CF is added, the volume of the fluid chamber CF is expanded, changing the clearance to D6 as shown in FIG. 19. Then, the fluid is absorbed under the small pressure by the biasing force of the elastic resin ring 19 relative to that of the coil spring 12 . In the seventh embodiment, in the same way, the relationship between the stroke of the piston 11 and the pressure in the fluid chamber CF of the low-pressure accumulator 10 is shown in FIG. 27, which shows that the fluid is absorbed at the low pressure (Pa) becomes. Furthermore, in the seventh embodiment, since the structure of the piston 11 is the same as that of the aforementioned embodiments of the low pressure accumulator and only a space for accommodating the elastic resin ring 19 is required, the manufacture is easy. The rest of the structure of the seventh embodiment of the low pressure accumulator used in the present invention is substantially the same as that of the embodiment in FIGS. 4, 5, so that the substantially same parts or components shown in FIG. 5 shown with the same numbers in the seventh embodiment, the explanation is not repeated here.

Fig. 20, 21 show the eighth embodiment of the low-pressure accumulator, which is used in the present invention. FIG. 20 shows the state before the low-pressure accumulator is operated as the receiving device, and FIG. 21 shows the state when the low-pressure accumulator works as the receiving device. In the eighth embodiment, a lower cylinder 111 , which is connected to the fluid chamber CF, is formed on the piston 110 . A lower piston 112 is slidably received in the lower cylinder 111 . Therefore, a sub-fluid chamber CS, which forms the receiving space of the present invention for receiving the fluid, is formed inside the sub-cylinder 111 . In addition, the sub-cylinder 111, as a sub-biasing means, receives a coil spring 113 therein by which the sub-cylinder 112 is biased in a direction in which the volume of the sub-fluid chamber CS is reduced.

In the non-working state of the receiving device, as shown in FIG. 20, the lower piston 112 is held in an initial position thereof in FIG. 20 by the biasing force of the coil spring 113 . Therefore, there is a space between the inner surface of the lower piston 112 and that of the cylinder 10 a D7. When the fluid flows into the sub-fluid chamber CS, the sub-piston 112 is driven by overcoming the biasing force of the coil spring 113 , and then the volume of the sub-fluid chamber CS is expanded. Accordingly, as shown in FIG. 21, the clearance is changed to D8 in which the fluid is absorbed under the small pressure by the biasing force of the coil spring 113 . A relationship between a stroke of the lower piston 112 and the pressure in the fluid chamber CF of the low pressure accumulator is as shown by a solid line in FIG. 26, which illustrates that the stroke of the piston 110 cannot be achieved until the pressure in the low pressure accumulator predetermined pressure (Pb) or more. However, as shown by the broken line in Fig. 26, the small stroke (Da) of the lower piston 112 can be achieved by the small pressure (Pa) which is less than the predetermined pressure (Pb), so that the fluid with the small Pressure (Pa) is received in the sub-fluid chamber CS. When the pressure in the fluid chamber CF or the sub-fluid chamber CS is reduced, the sub-piston 112 is returned in the direction of its initial position by the biasing force of the coil spring 113 . Then the fluid is returned to the sub-fluid chamber CS to the fluid chamber CF.

In the eighth embodiment, the piston 110 is not designed in the same way as the piston of the above-mentioned embodiments of the low-pressure accumulator, although z. B. the cylinder 10 a, is carried out in the same way as the cylinder of the aforementioned embodiments of the low pressure accumulator. However, since the coil spring 113 is used, the biasing force of which is set slightly, the property of the low-pressure accumulator is easily achieved. Since the remaining structure of the eighth embodiment of the low pressure accumulator used in the present invention is substantially the same as that of the embodiment in Figs. 4, 5, the substantially same parts or components shown in Figs. 5, the same numbers in the eighth embodiment, the explanation not being repeated here.

Fig. 22, 23 show the ninth embodiment of the low-pressure accumulator, which is used in the present invention. FIG. 22 shows the state before the low-pressure accumulator is operated as the receiving device, and FIG. 23 shows the state when the low-pressure accumulator operates as the receiving device. In the ninth embodiment, in addition to the embodiment shown in FIGS. 20, 21, a coil spring 114 is provided for biasing the lower piston 112 in a direction opposite to the biasing force of the coil spring 113 . The small pressure of the fluid in the sub-fluid chamber CS can be easily adjusted by the coil springs 113 , 114 .

In the non-working state of the receiving device, which is shown in FIG. 22 of the ninth exemplary embodiment, the lower piston 112 is held in its initial position, so that there is a free space between the inner surface of the lower piston 112 and that of the cylinder 10 a D9. When the fluid flows into the sub-fluid chamber CS, the sub-piston 112 is driven, in which case the volume of the sub-fluid chamber CS is expanded. Then, as shown in FIG. 23, the clearance is changed to D10 at which the fluid is taken up under the small pressure by a balance of the biasing forces between the coil spring 113 and the coil spring 114 . Further, in the ninth embodiment, as shown by the broken line in Fig. 26, the small stroke (Da) of the lower piston 112 can be achieved by the small pressure (Pa) which is less than the predetermined pressure (Pb), which Fluid under the low pressure (Pa) is received in the sub-fluid chamber CS. Since the rest of the structure of the ninth embodiment of the low pressure accumulator used in the present invention is substantially the same as that of the embodiment in Figs. 20, 21, the substantially same parts or components as those in Figs. 21, the same numbers in the ninth embodiment, and the explanation is not repeated here. In the ninth embodiment, the biasing force that biases the lower piston 112 can be easily adjusted by the coil springs 113 , 114 , so that the property of the low-pressure accumulator is achieved more easily than that of the embodiment in FIGS. 20, 21.

Fig. 24, 25 show the tenth embodiment of the low-pressure accumulator, which is used in the present invention. FIG. 24 shows the state before the low-pressure accumulator is operated as the receiving device, and FIG. 25 shows the state when the low-pressure accumulator operates as the receiving device. The lower cylinder 111 is accommodated in the piston 110 in the exemplary embodiment in FIGS. 20, 21, but the lower cylinder 111 is accommodated in the housing 1 in the tenth exemplary embodiment. In the tenth embodiment shown in FIGS . 24, 25, the sub-cylinder 111 connected to the fluid chamber CF is formed on the case 1 . The lower piston 112 is slidably received in the lower cylinder 111 . Therefore, the sub-fluid chamber CS, which forms the receiving space of the present invention, is formed in the sub-cylinder 111 for receiving the fluid.

As the sub-biasing means, the sub-cylinder 111 receives the coil spring 113 therein, thereby biasing the sub-piston 112 in the direction in which the volume of the sub-fluid chamber CS is reduced. Such a construction as that of the piston 11 is substantially the same as that of the embodiment in Figs. 4, 5, so that the substantially same parts and components shown in Figs. 4, 5 have the same numbers in the wear tenth embodiment, the explanation is not repeated here. Further, in the tenth embodiment, as shown by the broken line in Fig. 26, the small stroke (Da) of the lower piston 112 can be achieved by the small pressure (Pa) which is less than the predetermined pressure (Pb), which Fluid with the low pressure (Pa) is received in the sub-fluid chamber CS. In this exemplary embodiment, the construction of the piston 11 is the same as that of the aforementioned exemplary embodiments of the low-pressure accumulator, the receiving device of the present invention therefore being formed separately on the housing 1 . However, the property of the receiving device is easily achieved.

According to each of the above embodiments, the excess fluid in the compression chamber CP flows to the low pressure accumulator 10 side through each dispensing device even when the intake valve 7 is in the closed position. The excess fluid is then taken up in each receiver at the low pressure. Therefore, the pressure in the compression chamber CP cannot be increased at the next top dead center of the piston as shown by the solid line in Fig. 31, so that the occurrence of the noise can be prevented. With respect to the pressure increase in the compression chamber CP at this moment, the larger the volume ΔQ2 of the fluid flowing to the low-pressure accumulator 10 side becomes the volume ΔQ1 of the fluid flowing into the compression chamber CP through the outlet 6 , the more the pressure in the compression chamber CP increases at the next top dead center of the piston. However, pump efficiency is reduced when ΔQ2 is extremely large, so that ΔQ1 and ΔQ2 are preferably set approximately the same.

The piston pump according to any of the above The embodiment is as a control device (e.g. a Actuator used for the anti-lock braking system is) in a hydraulic pressure brake device of a vehicle suitable. However, the present invention is not based on this particular control device is limited, and can at Use in different flow devices Reduce pump drive.

The present embodiment of the invention having the above structure has the following effects:
The piston pump of the present invention is provided with the discharge permitting means to allow the small amount of the fluid to be discharged from the compression chamber to the low pressure accumulator side even when the intake valve is in a closed position, and the receptacle which accommodates the accommodating space has to receive the small amount of fluid that is dispensed from the dispenser and to receive the fluid at the small pressure that is less than the predetermined pressure. The piston pump of this invention with the simple structure can easily and surely reduce the noise of the pump resulting particularly from the operation of the exhaust valve.

In the piston pump as explained above, because the facility allowing the output by adding a small modification of the existing device can be the noise without enlarging the device to be reduced.

Furthermore, the one explained above Piston pump because the pick-up device is simply constructed can be the noise without enlarging the device to be reduced.

The principles, the preferred embodiment and the operating mode of the present invention are in the above specification has been described. The Invention to be protected, however, is not based on the disclosed specific embodiments are limited. Furthermore, those described herein Embodiments rather than illustrative rather than restrictive view. Variations and changes could be done by others and equivalents be used without departing from the gist of the invention departing. Accordingly, it is explicit intends all such variations, changes and equivalents that are within the essence of the present Invention fall as defined in the claims, are covered by this.

A piston pump with a housing, the one Compression chamber forms a piston that slides in the housing is received and to the compression chamber is exposed at one end, a drive cam for and moving the plunger, a dispensing valve, with the the compression chamber is connected, an inlet valve, connected to the compression chamber, and one Low pressure accumulator for holding fluid with a predetermined pressure or more with the compression chamber is connected through the inlet valve. Even if that Intake valve is in a closed position a small amount of the fluid from the compression chamber too the low-pressure storage side discharged through a slot, which is formed on the inlet valve. The small amount of the fluid that is dispensed through the slot is in a recording room recorded at a small pressure.

Claims (17)

1. Piston pump with:
a housing defining a compression chamber;
a piston slidably received in the housing and exposed to the compression chamber at one end;
drive means for reciprocating the piston;
an exhaust valve connected to the compression chamber;
an inlet valve connected to the compression chamber;
a low pressure accumulator for receiving fluid with a predetermined pressure or more, which is connected to the compression chamber through the inlet valve;
dispensing means for allowing a small amount of the fluid to be dispensed from the compression chamber to the low pressure accumulator side even when the intake valve is in a closed position; and
a receiving device having a receiving space for receiving the small amount of the fluid that is discharged from the dispensing device and for receiving the fluid under a pressure less than the predetermined pressure. 2. Piston pump according to claim 1, wherein the Inlet valve a valve seat and a valve section has always biased to sit on the valve seat is, with a slot on at least either that Valve section or the valve seat is designed to the Train the issuing facility. 3. Piston pump according to claim 1, wherein the piston slidably received in the housing by a sealing element is to allow the small amount of fluid from which Compression chamber to be output, the output allowing device formed by the sealing element is. 4. Piston pump according to claim 1, wherein the Low pressure accumulator a cylinder that with the Compression chamber is connected through the inlet valve a piston slidably received in the cylinder and forms a fluid chamber to hold the fluid in the cylinder record, and has a pretensioner to the Preload pistons in a direction where the volume the fluid chamber is reduced. 5. Piston pump according to claim 4, wherein the piston with a concave section is formed by a Membrane element is covered on a surface of the piston, which is exposed to the fluid chamber. 6. Piston pump according to claim 5, wherein the receiving space the recording facility through an expanded space is formed which is formed in the fluid chamber when the membrane element within the concave section is deformed. 7. Piston pump according to claim 5, wherein the Membrane element is formed integrally with the piston. 8. Piston pump according to claim 4, wherein an annular Groove is formed on an outer circumference of the piston, with an annular elastic element in the annular groove is inserted to a given space to form therebetween in a sliding direction of the piston. 9. Piston pump according to claim 8, wherein the receiving space the recording facility through an expanded space is formed between the annular elastic Element and the annular groove is formed if that annular element is deformed. 10. Piston pump according to claim 4, wherein a Reverse biasing device is provided to push the piston in an opposite direction to a biasing force of the Pretensioning device. 11. Piston pump according to claim 10, wherein the Recording space of the recording device by one extended space is formed in the fluid chamber, the by adjusting the preload of the Reverse biasing device relative to that of the Biasing device is set. 12. Piston pump according to claim 10, wherein the Reverse pretensioner is an elastic member that is arranged between the piston and the cylinder. 13. Piston pump according to claim 1, wherein the Pickup device a lower cylinder attached to the piston is designed to communicate with the fluid chamber, a lower piston sliding in the lower cylinder is received and a sub-fluid chamber for receiving the Forms fluids in the lower cylinder, and one Bottom biasing device has to turn the lower cylinder into a To bias direction in which the volume of the Under fluid chamber is reduced. 14. Piston pump according to claim 1, wherein the Pick-up device a lower cylinder attached to the housing is designed to communicate the fluid chamber, a Lower piston slidably received in the lower cylinder and a sub-fluid chamber for receiving the fluid in the lower cylinder, and one Has sub-biasing device to the lower piston in the To bias direction in which the volume of the Under fluid chamber is reduced. 15. Piston pump according to claim 3, wherein the Sealing element between a first annular groove and the Compression chamber is provided and in a second annular groove is inserted, leaving a small space is formed in between to accommodate the small amount of fluid allow it to be output to the compression chamber becomes. 16. Piston pump according to claim 15, wherein a Hydraulic channel between the sealing element and the second annular groove is formed to the small amount of Fluids to allow it from the compression chamber is output under a compressed state. 17. Piston pump according to claim 15, wherein a Sealing element between the drive cam and the first annular groove is provided.