JP4742091B2 - Master cylinder - Google Patents

Description

  The present invention relates to a master cylinder used in a vehicle brake device or the like.

  In the master cylinder, a piston is slidably fitted to a cylinder body into which hydraulic fluid is introduced from a reservoir, and a pressure chamber that pressurizes the hydraulic fluid in accordance with the operation of the piston is formed inside the cylinder main body. And a pressure chamber is connected to hydraulic equipment, such as a brake device, through piping, and operates hydraulic equipment according to operation of a piston. In addition, the cylinder body is provided with a supply passage for supplying hydraulic fluid from the reservoir to the pressure chamber in order to prevent the pressure in the pressure chamber from becoming negative when the piston returns.

  In recent years, vehicle dynamics control (VDC) for controlling the attitude of a vehicle has been developed. In such a system, a control pump that is a part of the hydraulic device at the time of VDC sucks the hydraulic fluid from the pressure chamber of the master cylinder and supplies the hydraulic fluid to the wheel braking unit. In this case, in the master cylinder, the hydraulic fluid corresponding to the amount sucked from the pressure chamber is replenished from the reservoir to the pressure chamber through the replenishment passage. However, when the suction amount of the control pump is large, the hydraulic fluid is insufficiently replenished It becomes easy to do.

Conventionally, as a master cylinder that copes with this, there is a known structure that opens another passage that connects a reservoir and a pressure chamber when hydraulic fluid is insufficient in the pressure chamber (for example, Patent Document 1). reference).
The master cylinder is provided with a bypass passage in the cylinder body that bypasses the replenishment passage and communicates the reservoir and the pressure chamber, and opens when the pressure in the pressure chamber becomes lower than the pressure in the reservoir. A check valve is provided.
JP-A-11-268629

  However, since this conventional master cylinder is provided with a check valve with a complicated structure and a large number of parts in the bypass passage that bypasses the replenishment passage, many man-hours such as processing and assembly are required during manufacture. In short, the problem is that the product cost is likely to rise.

  Therefore, the present invention aims to provide a master cylinder that can solve the shortage of hydraulic fluid in the pressure chamber with a simple structure and can obtain a smooth operation of the connected device without causing an increase in product cost. To do.

The invention according to claim 1, which solves the above problem, includes a cylinder body into which hydraulic fluid is introduced from a reservoir, and a piston that is slidably fitted to the cylinder body and defines a pressure chamber in the cylinder body. And a master cylinder having a supply passage formed in the cylinder body for supplying hydraulic fluid from the reservoir to the pressure chamber, a cylinder portion is connected to the pressure chamber in a system different from the supply passage. The cylinder portion is provided with a partition piston that slides within the cylinder portion to define a storage chamber connected to the pressure chamber and a back pressure chamber, and to separate the partition piston from the pressure chamber. An urging spring that urges the pressure chamber is provided, and when the pressure chamber becomes negative pressure, the hydraulic fluid in the storage chamber is replenished to the pressure chamber .

According to a second aspect of the present invention, in the master cylinder according to the first aspect, the storage chamber is always connected to the pressure chamber.

According to a third aspect of the present invention, in the master cylinder of the first or second aspect, the back pressure chamber is always connected to the reservoir.

According to a fourth aspect of the present invention, in the master cylinder according to the first or second aspect , the back pressure chamber is open to the atmosphere.

According to a fifth aspect of the present invention, there is provided a cylinder body into which hydraulic fluid is introduced from a reservoir, a piston slidably fitted in the cylinder body and defining a pressure chamber in the cylinder body, and the cylinder body. A master cylinder formed and provided with a supply passage for supplying hydraulic fluid from the reservoir to the pressure chamber, the bypass passage bypassing the supply passage and communicating the reservoir and the pressure chamber; A cylinder portion connected to the reservoir and the pressure chamber, a partition piston sliding the cylinder portion into a storage chamber and a back pressure chamber connected to the pressure chamber, and the partition Ri Na provided a biasing spring for biasing the piston into the reservoir direction, and wherein the hydraulic fluid of the reservoir chamber to replenish the pressure chamber when the pressure chamber is a negative pressure.

According to the present invention, since a shortage of hydraulic fluid in the pressure chamber is replenished from the storage chamber of the cylinder part different from the replenishment passage, smooth operation of the connected device can be obtained without causing an increase in product cost. Can do.

Further , according to the present invention, the inside of the cylinder portion is separated by the partition piston, and the partition piston is biased to the opposite side of the pressure chamber by the biasing spring. Can make up for the lack of. In particular, in the present invention, since the pressure chamber and the reservoir do not directly communicate with each other, the seal structure in the cylinder portion can be simplified.

Embodiments of the present invention will be described below with reference to the drawings. First, the first embodiment shown in FIGS. 1 to 3 will be described.
In the drawings, 1 is a master cylinder according to the present invention, and 2 is a reservoir attached to the upper part of the master cylinder 1. The master cylinder 1 of this embodiment is used in a vehicle brake device, and supplies hydraulic fluid to a brake circuit in conjunction with a brake operation at a driver's seat. In addition, a control pump (hydraulic device) for vehicle dynamics control (not shown) is provided in the brake circuit, and hydraulic fluid is supplied from the master cylinder 1 to the control pump separately from the driver's brake operation according to the driving situation of the vehicle. Is to be sucked.

  The master cylinder 1 is a tandem master cylinder in which a primary piston 4 and a secondary piston 5 are arranged in series in a bottomed cylindrical cylinder body 3, and is defined by both pistons 4, 5 in the cylinder body 3. The two pressure chambers 6 (only one pressure chamber 6 is shown in FIG. 1) are connected to different brake piping systems (for example, the brake piping system on the front wheel side and the rear wheel side) through the supply / discharge holes 10, respectively. Connected to the brake piping system).

  The primary piston 4 is slidably fitted to the opening side (the right side in FIG. 1) of the cylinder body 3, and the end of the opening side is connected to the operation rod of the brake pedal via a booster (not shown). . The secondary piston 5 is slidably fitted to the bottom of the cylinder body 3 and forms a pressure chamber 6 between the primary piston 4 and another pressure chamber (not shown) between the bottom of the cylinder body 3. Forming. In each pressure chamber 6, there is provided a return spring 8 that applies a reaction force in the return direction to the primary piston 4 and the secondary piston 5. Each return spring 8 is integrally assembled with a spring retainer 9 and is disposed in each pressure chamber 6 as a spring unit. Further, the primary piston 4 and the secondary piston 5 can be interlocked via a return spring 8 between them.

  Boss portions 11a and 11b for attaching the reservoir 2 are provided on the upper surface of the cylinder body 3, and cylindrical supply / discharge ports 12a and 12b (supply of hydraulic fluid) of the reservoir 2 are provided in the boss portions 11a and 11b. Part) is connected. The bosses 11a and 11b are recessed at substantially right angles toward the axis of the cylinder body 3, and are formed with connection recesses 20a and 20a for receiving the supply / discharge ports 12a and 12b of the reservoir 2. .

  On the other hand, annular grooves 14 (only one annular groove 14 is shown in FIG. 1) are formed at two positions spaced apart in the axial direction on the inner peripheral surface of the cylinder body 3, and each annular groove 14 and the connection are connected to each other. The recesses 20a and 20b are connected by the communication holes 13a and 13b. Each annular groove 14 is formed at a position facing the outer peripheral surfaces of the primary piston 4 and the secondary piston 5 and is connected to the corresponding pressure chamber 6 through a return hole 17 and a conduction groove 18 described later. Further, seal rings 15 and 16 are attached to the front and rear positions of the annular grooves 14 on the inner peripheral surface of the cylinder body 3 in the axial direction. The seal rings 15 and 16 allow the cylinder body 3 and the pistons 4 and 5 to slide. The moving gap is sealed fluid-tight.

  On the front side (left side in FIG. 1) of the annular groove 14 on the inner peripheral surface of the cylinder body 3, a conduction groove 18 that connects the annular groove 14 and the pressure chamber 6 is formed. Each conduction groove 18 is formed along the axial direction of the cylinder body 3, and the one seal ring 15 is interposed in the middle of the extension direction of each conduction groove 18. The seal ring 15 is formed in an E-shaped cross section, and is installed in the cylinder body 3 such that the opening side of the cross section faces forward (left side in FIG. 1), and the inner peripheral wall is slidable on the outer peripheral surface of each piston 4, 5. To come close. Further, when the pressure in the pressure chamber 6 on the front side becomes lower than the pressure in the annular groove 14 on the rear side, the seal ring 15 opens the conduction groove 18 by bending and deforming the outer peripheral wall, and the annular groove 14 ( The supply of the hydraulic fluid from the reservoir 2) to the corresponding pressure chamber 6 is allowed.

  Each of the primary and secondary pistons 4 and 5 is provided with a cylindrical wall 7 (only the cylindrical wall 7 on the piston 4 side is shown in FIG. 1) facing the pressure chamber 6 on the front side (left side in FIG. 1). Each cylindrical wall 7 is formed with a return hole 17 penetrating in the radial direction. The return holes 17 connect the pressure chambers 6 and the corresponding annular grooves 14 to each other when the pistons 4 and 5 are in the initial positions where the pistons 4 and 5 are retracted to the maximum. Set to atmospheric pressure.

  Therefore, when the pistons 4 and 5 are in the initial positions, the reservoir 2 and the pressure chambers 6 are electrically connected through the communication holes 13a and 13b, the annular grooves 14a and 14b, and the return holes 17 of the pistons 4 and 5, respectively. The hydraulic fluid is replenished from the reservoir 2 when the amount of hydraulic fluid in the pressure chamber 6 becomes insufficient due to the operation of dynamics control or the like. When the pistons 4 and 5 are moved forward from the initial position and the return hole 17 is shifted forward from the position facing the annular groove 14, the return hole 17 is closed, and the reservoir 2 and each pressure chamber 6 are closed. Is interrupted. At this time, the pressure in each pressure chamber 6 increases in accordance with the forward operation of each piston 4, 5, and the hydraulic fluid is supplied to the brake circuit through the supply / discharge hole 10. At the time of supplying the hydraulic fluid, the pressure in each pressure chamber 6 increases, and the force with which the seal ring 15 closes the conduction groove 18 increases.

Further, when the pistons 4 and 5 are retracted from the state by receiving the force of the return spring 8, the hydraulic fluid of the brake circuit is returned into the pressure chambers 6 through the supply / discharge holes 10. At this time, when the pressure in each pressure chamber 6 temporarily becomes lower than the internal pressure in the reservoir 2, the outer peripheral wall of the seal ring 15 bends and passes through the conduction groove 18 as described above. Insufficient hydraulic fluid is replenished from the reservoir 2.
In the case of this embodiment, the communication hole 13a, the annular groove 14, the return hole 17 and the conduction groove 18 constitute the supply passage 21 in the present invention.

  Meanwhile, an auxiliary reservoir block 30 that protrudes downward from one side surface is integrally formed at a substantially central position in the axial direction of the cylinder body 3. A concave portion 31 is formed on the end surface of the auxiliary reservoir block 30 (the lower end surface in FIGS. 2 and 3), and the opening end of the concave portion 31 is closed by a lid member 32, and a cylinder portion 33 (pressure accumulating chamber) is interposed therebetween. ) Is formed. The cylinder portion 33 is disposed with the inner substantially cylindrical space facing the vertical direction when the master cylinder 1 is attached to the vehicle body.

  The upper part of the cylinder part 33 is connected to the connection recess 20 a by the first communication path 34, and the lower part of the cylinder part 33 is connected to the pressure chamber 6 on the primary piston 4 side by the second communication path 35. The first communication path 34 and the second communication path 35 constitute a bypass path 36 that bypasses the supply path 21 and connects the reservoir 2 and the pressure chamber 6. 2 and 3, reference numerals 33a and 33b denote connection ports on the first communication path 34 side and the second communication path 35 side of the cylinder portion 33, respectively. The cylinder 33 is slidably accommodated therein with a partition piston 39 that defines a back pressure chamber 37 on the first communication path 34 side and a storage chamber 38 on the second communication path 35 side. The storage chamber 38 accommodates a coil spring 40 (biasing spring) that biases the partition piston 39 toward the back pressure chamber 37 (reservoir 2 direction). An annular seal member 41 is mounted on the outer peripheral surface of the partition piston 39, and the seal member 41 maintains liquid tightness between the inner wall of the cylinder portion 33 and the partition piston 39.

  Here, the pressure (atmospheric pressure) in the reservoir 2 acts on the partition piston 39 on the back pressure chamber 37 side in the cylinder portion 33, and the pressure in the pressure chamber 6 of the cylinder body 3 and the coil spring on the storage chamber 38 side. A spring force of 40 acts on the partition piston 39. Therefore, until the pressure in the pressure chamber 6 is reduced by the set pressure corresponding to the set load of the coil spring 40 with respect to the atmospheric pressure, the partition piston 39 is maintained at the initial highest position as shown in FIG. The maximum amount of hydraulic fluid is stored in the storage chamber 38. When the pressure in the pressure chamber 6 falls below the set pressure from this state, the partition piston 39 descends against the spring force of the coil spring 40 and is stored in the storage chamber 38 as shown in FIG. The working fluid is supplied to the pressure chamber 6 through the second communication passage 35.

  In the above configuration, the vehicle dynamics control is activated while the vehicle is running, and the control pump in the brake circuit sucks up the hydraulic fluid from the master cylinder 1 side. Accordingly, the pressure in the pressure chamber 6 is higher than the pressure in the reservoir 2. When the pressure drops below the set pressure, the partition piston 39 in the auxiliary reservoir block 30 is lowered as described above, and the hydraulic fluid in the storage chamber 38 is replenished into the pressure chamber 6. Accordingly, a sufficient amount of hydraulic fluid can be quickly supplied from the pressure chamber 6 to the control pump, so that desired vehicle dynamics control can be stably obtained and negative pressure in the master cylinder 1 can be obtained. Generation of pressure is also suppressed. Thus, for example, when the vehicle dynamics control is activated in a state where the driver applies a brake during cornering, the primary piston 4 is replenished from the storage chamber 38 into the pressure chamber 6 even during the forward stroke. The liquid can make up for the shortage of intake by the control pump.

  In the master cylinder 1, when the pressure chamber 6 is reduced by a set pressure or more when the vehicle dynamics control is operated as described above, the pressure chamber 6 is moved from the storage chamber 38 having a simple structure separate from the normal supply passage 21 to the pressure chamber 6. Therefore, the brake system can be smoothly operated while suppressing an increase in product cost.

  In particular, in the master cylinder 1, the inside of the cylinder portion 33 is defined by a partition piston 39 into a storage chamber 38 and a back pressure chamber 37, and the partition piston 39 is attached to the back pressure chamber 37 side by a coil spring 40. Since the structure is energized, the hydraulic fluid having an appropriate flow rate corresponding to the shortage in the pressure chamber 6 can be quickly supplemented with a very simple configuration. Further, in the case of the master cylinder 1, the storage chamber 38 and the reservoir 2 are not in direct communication with each other, so that the seal structure of the partition piston 39 can be simplified and the product cost can be reduced more advantageously. it can.

  Further, the master cylinder 1 has a structure in which a bypass passage 36 that bypasses the supply passage 21 and communicates the reservoir 2 and the pressure chamber 6 is provided, and a cylinder portion 33 that forms a pressure accumulating chamber is disposed in the middle of the bypass passage 36. Therefore, there is an advantage that the cylinder part 33 can be arranged at an arbitrary position in the bypass passage 36 and the degree of freedom in layout is high.

  Next, a second embodiment of the present invention shown in FIGS. 4 to 6 will be described. In the following description of each embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

The basic configuration of the master cylinder 101 of this embodiment is substantially the same as that of the first embodiment, but only the arrangement of the auxiliary reservoir block 130 that forms the cylinder portion 33 is different from that of the first embodiment.
In other words, in the case of the master cylinder 101, the auxiliary reservoir block 130 is integrally formed so as to protrude outward from the base position of the reservoir connecting boss portion 11a protruding upward from the cylinder body 3. . As shown in FIGS. 5 and 6, the cylinder portion 33 is directed in a substantially horizontal direction when the master cylinder 101 is attached to the vehicle body, and the back pressure chamber 37 is directed through the first communication passage 34 that is substantially horizontal. The storage chamber 38 is connected to the pressure chamber 6 via a second communication passage 35 that is inclined obliquely downward.

  The master cylinder 101 can obtain the same basic operations and effects as those of the first embodiment, but the boss portion 11a protruding from the cylinder body 3 and the auxiliary reservoir block 130 are integrated in one place. Since it is arranged, there is an advantage that the whole is compact and advantageous for mounting on a vehicle.

FIG. 7 shows a third embodiment of the present invention.
As in the first and second embodiments, the master cylinder 201 of this embodiment is provided with a cylinder portion 33 that is connected to the pressure chamber 6 via the communication path 35, and the cylinder portion 33 stores the inside. The partition piston 39 defined in the chamber 38 and the back pressure chamber 37 is slidably received, and the partition piston 39 is biased toward the back pressure chamber 37 by the coil spring 40. The back pressure chamber 37 is not connected to the reservoir, but communicates with the atmosphere through the open hole 50.

  The master cylinder 201 can obtain the same basic operations and effects as those of the first and second embodiments, but the back pressure chamber 37 communicates with the atmosphere through the open hole 50, so that the passage There is an advantage that the structure can be simplified and the manufacturing cost can be reduced and the entire apparatus can be made compact.

  In addition, this invention is not limited to said embodiment, A various design change is possible in the range which does not deviate from the summary. For example, each of the above embodiments has been described with respect to a tandem master cylinder, but may be a single master cylinder having a single piston.

1 is a longitudinal sectional view of a master cylinder of a first embodiment of the present invention. Sectional drawing at the time of the hydraulic fluid storage corresponding to the AA cross section of FIG. 1 which shows the same embodiment. Sectional drawing at the time of the hydraulic fluid supply corresponding to the AA cross section of FIG. 1 which shows the same embodiment. The longitudinal cross-sectional view of the master cylinder of 2nd Embodiment of this invention. Sectional drawing at the time of the hydraulic fluid storage corresponding to the BB cross section of FIG. 4 which shows the same embodiment. Sectional drawing at the time of hydraulic fluid supply corresponding to the BB cross section of FIG. 4 which shows the same embodiment. Sectional drawing at the time of hydraulic fluid supply which shows the 3rd Embodiment of this invention.

Explanation of symbols

1, 101, 201 ... master cylinder 2 ... reservoir 3 ... cylinder body 4 ... primary piston (piston)
6 ... Pressure chamber 21 ... Supply passage 33 ... Cylinder part (accumulation chamber)
33b ... Connection port 36 ... Bypass passage 39 ... Bulkhead piston 40 ... Coil spring (biasing spring)

Claims (5)

A cylinder body into which hydraulic fluid is introduced from a reservoir; a piston slidably fitted in the cylinder body to define a pressure chamber in the cylinder body; and the pressure chamber formed in the cylinder body from the reservoir. A master cylinder having a supply passage for supplying hydraulic fluid to
A cylinder portion is connected to the pressure chamber in a separate system from the supply passage ,
The cylinder part is provided with a partition piston that defines and slides in the cylinder part into a storage chamber and a back pressure chamber connected to the pressure chamber,
An urging spring for urging the partition piston in a direction away from the pressure chamber is provided, and the hydraulic fluid in the storage chamber is replenished to the pressure chamber when the pressure chamber becomes negative pressure. Master cylinder to be used. The master cylinder according to claim 1, wherein the storage chamber is always connected to the pressure chamber. The master cylinder according to claim 1 or 2, wherein the back pressure chamber is always connected to the reservoir . The master cylinder according to claim 1, wherein the back pressure chamber is open to the atmosphere . A cylinder body into which hydraulic fluid is introduced from a reservoir; a piston slidably fitted in the cylinder body to define a pressure chamber in the cylinder body; and the pressure chamber formed in the cylinder body from the reservoir. A master cylinder having a supply passage for supplying hydraulic fluid to
A bypass passage that bypasses the replenishment passage and communicates the reservoir and the pressure chamber; a cylinder portion connected to the reservoir and the pressure chamber; and the cylinder portion connected to the pressure chamber a partition wall piston sliding defining the the storage chamber and the back pressure chamber to be connected to, Ri Na provided a biasing spring for biasing the septum piston into the reservoir direction, the pressure chamber is a negative pressure The master cylinder is characterized in that the hydraulic fluid in the storage chamber is replenished to the pressure chamber when the pressure reaches the value.

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