JP2013203182A - Master cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a master cylinder having an idle stroke set to be longer than usual, to have a short idle stroke at low temperature.SOLUTION: In a master cylinder 100, a piston 21 slides on inner peripheries of cups 41, 42 held by a cylinder body 10 to pressurize brake liquid in a pressure chamber R1. The piston 21 is provided with a main port 21a and a sub port 21b which communicate the pressure chamber R1 to a reservoir 30 in a non-operation condition, at a distance of a predetermined length in a sliding direction, and when the piston 21 operates, the sub port 21b is disconnected from the reservoir 30 after the main port 21a is disconnected from the reservoir 30. The piston 21 is provided with an opening/closing member 81 which closes at least a part of the sub port 21b when a temperature of brake liquid is equal to or less than a set value and opens the sub port 21b when a temperature of the brake liquid exceeds the set value.

Description

  The present invention relates to a master cylinder that is applied to a vehicle brake device, and in particular, has a larger idle stroke than a normal master cylinder (used in a vehicle brake device that does not include a regenerative brake device). The present invention relates to a master cylinder that is most suitable as a master cylinder for regenerative coordination (used in a vehicle brake device equipped with a regenerative brake device).

  As one of vehicle brake devices, in a vehicle brake device that achieves a target braking force to be applied to a vehicle according to a brake operation state by a hydraulic braking force by a hydraulic brake device and a regenerative braking force by a regenerative braking device, Patent Document 1 listed below aims to achieve high regenerative efficiency, that is, low fuel consumption, by actively using regenerative braking force in a low depressing force region from the start of pedal depression to a predetermined state. It is described in.

JP 2010-202188 A

  The purpose mentioned above (that is, to achieve low fuel consumption by high regenerative efficiency) is to make the idle stroke longer than usual in the master cylinder that operates in response to depression of the brake pedal and generates hydraulic pressure, This can be achieved by setting so that the regenerative braking force can be obtained in the idle stroke operation region.

  By the way, in the master cylinder described above, the cup-shaped piston slides on the inner periphery of the cup held by the cylinder body, so that the brake fluid in the pressure chamber is pressurized. A main port and a sub port for communicating the pressure chamber with the reservoir when not operating are provided apart by a predetermined amount in the sliding direction (piston axial direction). When the piston is operated, the main port is connected to the reservoir. If the subport is set to block communication with the reservoir after the communication is cut off, the idle stroke is lengthened by increasing the separation amount (predetermined amount) between the main port and the subport. It is possible.

  However, when the regenerative braking device described above is configured to operate the regenerative pump that pressurizes the brake fluid during regenerative braking to obtain the regenerative braking force, the regenerative braking device is used at a low temperature (the brake fluid When the temperature is equal to or lower than the set value, the pressurization capacity of the regenerative pump may be reduced due to the increase in the viscosity of the brake fluid.

The present invention has been made to cope with the above-described problems (that is, in a master cylinder set so that the idle stroke becomes longer than usual, the idle stroke is substantially reduced at low temperatures. Stuff),
The cup-shaped piston slides on the inner periphery of the cup held by the cylinder body, so that the brake fluid in the pressure chamber is pressurized, and the piston is provided with the pressure chamber when not operating. A main port and a sub port communicating with the reservoir are provided apart from each other by a predetermined amount in the sliding direction, and when the piston is operated, the sub port communicates with the reservoir after the main port is disconnected from the reservoir. A master cylinder set to be shut off,
The piston is provided with an opening / closing member that closes at least a part of the subport when the temperature of the brake fluid is lower than a set value and opens the subport when the temperature of the brake fluid exceeds a set value. There is a feature.

  In the master cylinder according to the present invention, the opening / closing member is made of a single material (for example, a resin material) having a linear expansion coefficient larger than that of the material of the piston, and the single material includes the brake fluid. It is also possible to form a communication hole that opens the sub-port when the temperature exceeds the set value. In this case, the opening / closing member may be formed in a cylindrical shape accommodated in the piston, and the communication hole may be formed in an arc shape having the same width in the piston axial direction and extending in the circumferential direction. It is. Further, in the master cylinder according to the present invention, the opening / closing member is made of a bimetal, and the bimetal is set so that the subport is fully opened when the temperature of the brake fluid exceeds a set value. It is also possible.

  In the master cylinder according to the present invention, the piston is provided with an opening / closing member that closes at least a part of the subport when the brake fluid temperature is equal to or lower than the set value and opens the subport when the brake fluid temperature exceeds the set value. . For this reason, when the temperature of the brake fluid exceeds the set value, the opening / closing member opens the subport, whereby the pressure chamber and the reservoir communicate with each other through the subport, and the desired idle stroke (the idle stroke longer than usual) ) Is obtained. Therefore, the desired high regenerative efficiency can be obtained in the regenerative brake device employed together with the master cylinder.

  By the way, when the temperature of the brake fluid is equal to or lower than a set value (low temperature), the opening / closing member closes at least a part of the subport, thereby suppressing or blocking communication between the pressure chamber and the reservoir via the subport. For this reason, the desired idle stroke cannot be obtained in the master cylinder, and the idle stroke is substantially shortened. Therefore, the hydraulic braking force by the hydraulic brake device that operates in accordance with the operation of the master cylinder increases, and the shortage of the regenerative braking force of the regenerative brake device due to the decrease in the pressurization capability of the regenerative pump can be compensated. It is possible to ensure the braking effectiveness of the.

  In implementing the present invention described above, the opening / closing member may be assembled to the piston using a spring retainer that engages with one end of a spring that urges the piston toward the return position. In this case, the existing member (spring retainer) in the master cylinder can be effectively used, and the opening / closing member can be assembled to the piston, which can be implemented at low cost.

It is the vertical side view which showed 1st Embodiment of the master cylinder by this invention. It is a perspective view of the opening-and-closing member shown in FIG. It is a principal part expanded sectional view which showed schematically the relationship between the primary piston shown in FIG. 1, and an opening-and-closing member, (a) shows the state at the time of high temperature, (b) shows the state at the time of normal temperature, (c ) Is a diagram showing a state at a low temperature (when the temperature of the brake fluid is equal to or lower than a set value). FIG. 3 is a perspective view of an opening / closing member that can be used in place of the opening / closing member shown in FIGS. 1 and 2. It is the vertical side view which showed 2nd Embodiment of the master cylinder by this invention. FIG. 6 is an enlarged cross-sectional view of a main part schematically illustrating a relationship (a relationship at normal temperature) between the primary piston and the opening / closing member illustrated in FIG. 5.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show a first embodiment of a master cylinder according to the present invention. In the master cylinder 100 of the first embodiment, a cup-shaped primary piston 21 and a cup-shaped secondary piston 22 are provided on a cylinder body 10. A first pressure chamber R1 and a second pressure chamber R2 are formed in the cylinder body 10 so as to be slidable in the piston axial direction, and a reservoir 30 for accommodating brake fluid is provided on the cylinder body 10. It is fixed in a liquid-tight manner.

  In the master cylinder 100 of the first embodiment, inside the cylinder body 10, a primary cup 41 that seals the outer periphery of the primary piston 21, a secondary cup 42 that blocks the cylinder and the atmosphere at the outer periphery of the primary piston 21, and a secondary A primary cup 43 that seals the outer periphery of the piston 22 and a pressure cup 44 that blocks between the first pressure chamber R1 and the liquid chamber R4 (communicating with the reservoir 30) on the outer periphery of the secondary piston 22 are arranged. Yes.

  Each of the cups 41 to 44 is incorporated in an annular cup storage groove provided on the inner periphery of the cylinder body 10 and is held by the cylinder body 10. Further, the liquid chamber R3 formed between the cups 41 and 42 and the liquid chamber R4 formed between the cups 43 and 44 communicate with the reservoir 30 through the passages formed in the cylinder body 10. ing.

  For this reason, in the first embodiment, the cup-shaped primary piston 21 is guided by the cylinder body 10 on the inner circumference of both cups 41 and 42 held by the cylinder body 10 and can slide in the piston axial direction. And it is comprised so that the brake fluid of 1st pressure chamber R1 may be pressurized by sliding toward 1st pressure chamber R1. The cup-shaped secondary piston 22 is slidable in the direction of the piston axis guided by the cylinder body 10 on the inner periphery of both cups 43 and 44 held by the cylinder body 10, and is provided in the second pressure chamber R2. Is configured such that the brake fluid in the second pressure chamber R2 is pressurized.

  The brake fluid pressure generated in the first pressure chamber R1 is output to the outside of the master cylinder 100 through the first output port 11 provided in the cylinder body 10, and the brake fluid generated in the second pressure chamber R2 is It is output to the outside of the master cylinder 100 through the second output port 12 provided in the body 10. The brake fluid output to the outside of the master cylinder 100 is configured to be supplied to a hydraulic brake device (not shown) that operates as the master cylinder 100 operates.

  In the first embodiment, a return spring 51 and spring retainers 61 and 71 for returning the primary piston 21 to the return position (the non-operation position shown in FIG. 1) are assembled between the primary piston 21 and the secondary piston 22. It is attached. Further, a return spring 52 and spring retainers 62 and 72 for returning the secondary piston 22 to a return position (non-operation position) are assembled between the secondary piston 22 and the cylinder body 10. Each of the spring retainers 61 and 62 is fixed to the center of each of the dish-shaped members 61a and 62a and is fixed to each of the pistons 21 and 22, and the spring retainers 71 and 72 are fixed to the center of the dish-shaped members 61a and 62a. It is comprised by the rod-shaped members 61b and 62b which can be engaged / disengaged.

  Further, in the first embodiment, as shown in FIGS. 1 and 3, the primary piston 21 is provided with a main port 21a and a sub port 21b (both are piston ports). The main port 21a and the sub port 21b communicate the first pressure chamber R1 with the reservoir 30 when the primary piston 21 is not in operation, and are provided a predetermined amount apart in the sliding direction (piston axial direction). Further, as shown in FIG. 1, the secondary piston 22 is provided with a piston port 22a. The piston port 22a allows the second pressure chamber R2 to communicate with the reservoir 30 when the secondary piston 22 is not operated.

  By the way, in the first embodiment, the opening area (opening diameter) of the main port 21a is set larger than the opening area of the subport 21b, and the main port 21a is connected to the reservoir 30 when the primary piston 21 is operated. The subport 21b is set so that the communication with the reservoir 30 is blocked after the communication with the reservoir 30 is blocked.

  In the first embodiment, the primary piston 21 is provided with an opening / closing member 81. The opening / closing member 81 is made of a single material (for example, a resin material) having a larger linear expansion coefficient than that of the material (for example, aluminum alloy) of the primary piston 21, and as shown in FIG. It is formed in a cylindrical shape having an arc-shaped communication hole 81 a that has the same width in the direction and extends in the circumferential direction, and is accommodated in the accommodation hole of the primary piston 21. The opening / closing member 81 is positioned and fixed by engaging with an annular protrusion provided on the dish-like member 61a of the spring retainer 61 at an annular flange portion 81b provided at the base end (right end in FIG. 1) (FIG. 1). FIG. 2).

  By the way, in the opening / closing member 81, when the temperature of the brake fluid is equal to or lower than a set value (for example, at the low temperature shown in FIG. 3C), the communication hole 81a is displaced in the piston axial direction with respect to the subport 21b. When the sub-port 21b is closed as a whole, the communication between the first pressure chamber R1 and the reservoir 30 is blocked, and the temperature of the brake fluid exceeds a set value (for example, (b) in FIG. 3). When the normal temperature shown in FIG. 3 and the high temperature shown in FIG. 3A), the communication hole 81a is deformed so as to overlap with the sub port 21b in the piston axial direction, thereby opening all of the sub port 21b. Thus, the first pressure chamber R1 and the reservoir 30 are set to communicate with each other.

  The master cylinder 100 of the first embodiment described above is used by being assembled to the housing 201 (front shell) of the brake booster 200 as shown in FIG. The primary piston 21 is pushed by 202 against the urging force of the return spring 52. The master cylinder 100 of the first embodiment described above is a regenerative brake device (not shown) (this regenerative brake device is driven by an electric motor as described in, for example, JP 2010-202188 A). And a regenerative pump that generates brake fluid pressure).

  In the master cylinder 100 of the first embodiment configured as described above, the subport 21b is closed when the brake fluid temperature is equal to or lower than the set value, and the subport 21b is opened when the brake fluid temperature exceeds the set value. An opening / closing member 81 is provided on the primary piston 21. For this reason, when the temperature of the brake fluid exceeds the set value, the opening / closing member 81 opens the subport 21b, whereby the first pressure chamber R1 and the reservoir 30 are communicated with each other via the subport 21b. Longer idle stroke). Therefore, in the regenerative braking device (not shown) employed together with the master cylinder 100, the desired high regenerative efficiency can be obtained.

  By the way, when the temperature of the brake fluid is equal to or lower than the set value (during low temperature), the open / close member 81 closes all of the subport 21b, thereby blocking communication between the first pressure chamber R1 and the reservoir 30 via the subport 21b. Is done. For this reason, the desired idle stroke cannot be obtained in the master cylinder 100, and the idle stroke is shortened. Therefore, the hydraulic braking force by the hydraulic brake device that operates in accordance with the operation of the master cylinder 100 can be increased to compensate for the insufficient regenerative braking force of the regenerative brake device that accompanies a decrease in the pressurization capability of the regenerative pump. It is possible to ensure the braking effect of the period.

  Further, in the master cylinder 100 of the first embodiment described above, the opening / closing member 81 includes the plate-like member 61a of the spring retainer 61 that engages with one end of the return spring 51 that biases the primary piston 21 toward the return position. Used to be assembled to the primary piston 21. For this reason, the opening / closing member 81 can be assembled to the primary piston 21 by effectively utilizing the existing member (spring retainer 61) in the master cylinder 100, which can be implemented at low cost.

  Further, in the master cylinder 100 of the first embodiment described above, the opening / closing member 81 is formed in a cylindrical shape that is accommodated in the primary piston 21, and the communication hole 81 a has the same width in the piston axial direction and the circumference. It is formed in an arc shape extending in the direction. For this reason, the positioning in the circumferential direction when the opening / closing member 81 is assembled to the primary piston 21 is easy, and the assembling property of the opening / closing member 81 with respect to the primary piston 21 can be improved.

  In the first embodiment described above, as shown in FIG. 2, the opening / closing member 81 is formed in a cylindrical shape having an arc-shaped communication hole 81a having the same width in the piston axial direction and extending in the circumferential direction. However, as in the modified embodiment shown in FIG. 4, the opening / closing member 81A is implemented as a shape having a tongue piece portion having a circular communication hole 81a and an annular mounting portion having an annular flange portion 81b. It is also possible to do. When the opening / closing member 81A is employed, it is necessary to accurately perform alignment in the circumferential direction when the opening / closing member 81A is assembled to the primary piston 21 (alignment of the sub-port 21b and the circular communication hole 81a). is there.

  Further, in the first embodiment described above, the opening / closing member 81 (81A) is configured with a single material (for example, a resin material), but as in the second embodiment shown in FIGS. 5 and 6, The opening / closing member 81B may be formed of bimetal. The opening / closing member 81 (81A) of the first embodiment described above is not limited to a resin material as long as the material has a larger linear expansion coefficient than the material of the primary piston 21.

  In the opening / closing member 81B of the second embodiment, when the temperature of the brake fluid exceeds the set value, as shown in FIGS. 5 and 6, the subport 21b provided in the primary piston 21 is deformed to open, The first pressure chamber R1 and the reservoir 30 are communicated with each other via the subport 21b, and at least a part of the subport 21b provided in the primary piston 21 is closed when the temperature of the brake fluid is equal to or lower than a set value. The communication between the first pressure chamber R1 and the reservoir 30 via the subport 21b is suppressed or blocked.

  The other configurations of the second embodiment shown in FIGS. 5 and 6 are substantially the same as the corresponding configurations of the first embodiment shown in FIGS. For this reason, also in this 2nd Embodiment, it is possible to obtain the same effect as the above-mentioned 1st Embodiment. In the second embodiment, the opening / closing member 81B can be formed in the shape shown in FIG.

  The set value (brake fluid temperature) employed in each of the above embodiments takes into consideration the viscosity characteristics of the brake fluid employed in the master cylinder, the performance of the regenerative pump employed in the regenerative brake device, and the like. The temperature of the brake fluid is adopted as the set value so that the viscosity of the brake fluid increases due to a decrease in the temperature of the brake fluid, and the performance of the regenerative pump is significantly decreased.

  In each of the embodiments described above, the present invention is applied to the primary piston 21 in the tandem master cylinder 100. However, the present invention is not limited to the secondary piston 22 of the master cylinder 100, for example, in a single master cylinder. The piston can also be carried out in the same manner as in the above-described embodiments or with appropriate modifications, and is not limited to the above-described embodiment.

DESCRIPTION OF SYMBOLS 10 ... Cylinder body, 11, 12 ... Output port, 21 ... Primary piston, 21a ... Main port, 21b ... Sub port, 22 ... Secondary piston, 22a ... Piston port, 30 ... Reservoir, 41 ... Primary cup, 42 ... Secondary cup, 43 ... Primary cup, 44 ... Pressure cup, 51, 52 ... Return spring, 61, 62, 71, 72 ... Spring retainer, 61a, 62a ... Dish-shaped member, 61b, 62b ... Rod-shaped member, 81, 81A, 81B ... Opening and closing member, 81a ... communication hole, 81b ... annular flange, 100 ... master cylinder, R1 ... first pressure chamber, R2 ... second pressure chamber, R3, R4 ... liquid chamber

Claims (5)

The cup-shaped piston slides on the inner periphery of the cup held by the cylinder body, so that the brake fluid in the pressure chamber is pressurized, and the piston is provided with the pressure chamber when not operating. A main port and a sub port communicating with the reservoir are provided apart from each other by a predetermined amount in the sliding direction, and when the piston is operated, the sub port communicates with the reservoir after the main port is disconnected from the reservoir. A master cylinder set to be shut off,
The piston is provided with an opening / closing member that closes at least a part of the subport when the temperature of the brake fluid is below a set value and opens the subport when the temperature of the brake fluid exceeds a set value. Cylinder.   2. The master cylinder according to claim 1, wherein the opening and closing member is formed of a single material having a linear expansion coefficient larger than that of the material of the piston, and the single material has a temperature of the brake fluid. A master cylinder having a communication hole that opens the sub-port when the set value is exceeded.   2. The master cylinder according to claim 1, wherein the opening and closing member is made of a bimetal, and the bimetal is set so that the subport is fully opened when a temperature of the brake fluid exceeds a set value. Master cylinder.   3. The master cylinder according to claim 2, wherein the opening / closing member is formed in a cylindrical shape accommodated in the piston, and the communication hole is formed in an arc shape having the same width in the piston axial direction and extending in the circumferential direction. Master cylinder being used. 5. The master cylinder according to claim 1, wherein the opening / closing member is assembled to the piston using a spring retainer that engages one end of a spring that urges the piston toward a return position. 6.

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