JP2012076550A - Plunger type master cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plunger type master cylinder capable of improving brake feeling during a driver's braking operation while making suction properties satisfactory during brake control without depending upon a driver's operation.SOLUTION: In a state where a piston 21 is in an inoperative position, the front end of a sealing point section 31b1 of endless form which is mounted on the internal periphery of the tip portion of the internal periphery lip section 31b in a seal ring 31 and which can be seal-connected to the external periphery wall surface of the piston 21 is mounted nearer to a hydraulic chamber side than a plurality of piston ports 21a which are provided in the piston 21 and which are arranged in the peripheral direction at the identical axial position to open in the external periphery wall surface of the piston 21 and to communicate with the hydraulic chamber Rp1 and to be equally open to a communication path. A mounting area of the sealing point section 31b1 in the seal ring 31 is defined with a predetermined axial width W, and the sealing point section 31b1 is formed into such a shape as to make an axial round trip in the mounting area (W).

Description

  The present invention relates to a plunger type master cylinder employed in a vehicle hydraulic brake device, and in particular, brake control (for example, automatic brake control or traction control for vehicle attitude control) separately from a brake operation by a driver. The present invention relates to a plunger-type master cylinder suitable for a hydraulic brake device configured to perform the above.

  As one of this type of plunger-type master cylinder, a cylinder body having a cylinder bore extending in the axial direction from the closed end portion to the open end portion and having a communication passage for communicating the cylinder bore and the reservoir, and the cylinder body A piston which is assembled in the cylinder bore so as to be movable in the axial direction and forms a hydraulic chamber on the closed end side, and an annular base portion provided on the cylinder body on the outer periphery of the piston. A seal ring having a cylindrical inner peripheral lip portion and an outer peripheral lip portion extending from the inner and outer peripheral portions of the base portion toward the hydraulic pressure chamber side, and the piston provided in the hydraulic pressure chamber in a non-operating position. And a return mechanism for returning to the inner periphery of the inner peripheral lip portion of the seal ring when the piston is in a non-operating position. An endless seal point portion that can be seal-bonded to the outer peripheral wall surface of the piston is provided on the piston, opens to the outer peripheral wall surface of the piston, and communicates with the hydraulic chamber from the plurality of piston ports. And the hydraulic pressure chamber is configured to communicate with the reservoir through the piston port and the communication path. For example, Patent Document 1 below discloses.

JP 2005-112188 A

  In the plunger type master cylinder described in Patent Document 1 described above, two types of ports, that is, a plurality of suction passage ports and a plurality of communication guarantee ports, are set as the piston ports. The number of suction passage ports is larger than the number of communication guarantee ports, and the suction passage ports are arranged in front of the piston in the forward direction (hydraulic pressure chamber side) of the communication guarantee ports. Therefore, in the state where the piston is in the non-operating position, the opening area of the communication guarantee port is added to the opening area of the suction passage port, so that the passage area by the piston port can be sufficiently secured. Thus, it is possible to improve the suction performance during brake control not depending on the driver's operation. In addition, the suction passage port located in front of the piston in the forward direction of the piston is closed earlier than the communication guarantee port, and the passage area between the hydraulic chamber and the reservoir is drastically reduced at this stage. In addition, an increase in pressure in the hydraulic chamber occurs and the sense of invalid stroke is reduced.

  By the way, in the plunger type master cylinder described in the above-mentioned patent document 1, it can be estimated that the seal point portion of the seal ring is formed in a circular shape (annular at the same position in the axial direction), and for the suction passage. When the port is closed at the beginning of the forward movement of the piston, a plurality of suction passage ports are simultaneously closed in the same form, so that a sudden pressure change occurs in the hydraulic chamber and the communication guarantee port is connected to the piston. When closing by forward operation, a plurality of communication guarantee ports are simultaneously closed in the same form, thereby causing a sudden pressure change in the hydraulic chamber. These pressure changes may cause the driver to feel uncomfortable, and the brake feeling may be impaired.

  The present invention has been made to solve the above-described problem, and has a cylinder inner hole extending in the axial direction from the closed end to the open end, and a cylinder body having a communication path for communicating the cylinder inner hole and the reservoir. A piston which is assembled in the cylinder bore of the cylinder body so as to be movable in the axial direction and forms a hydraulic chamber on the closed end side, and is provided on the cylinder body on the outer periphery of the piston. An annular base portion, a seal ring having a cylindrical inner peripheral lip portion and an outer peripheral lip portion respectively extending from the inner and outer peripheral portions of the base portion toward the hydraulic pressure chamber, and provided in the hydraulic pressure chamber, And a return mechanism for returning the piston to the non-operating position. When the piston is in the non-operating position, the piston is provided on the inner periphery of the inner lip portion of the seal ring. A front end of an endless seal point portion that can be sealed and connected to the outer peripheral wall surface of the piston is provided in the piston and opens to the outer peripheral wall surface of the piston and communicates with the hydraulic chamber and opens equally to the communication passage. The plurality of piston ports arranged in the circumferential direction at the same position in the axial direction is set on the hydraulic pressure chamber side, and the hydraulic pressure chamber is connected to the reservoir through the piston port and the communication path. A plunger-type master cylinder configured to communicate with each other, wherein an installation region of the seal point portion in the seal ring is set with a predetermined axial width, and the seal point portion has the installation region in the axial direction; And at least one reciprocating shape. In this case, it is desirable that the shape of the seal point portion developed in the circumferential direction is V-shaped.

  In the plunger type master cylinder according to the present invention, in a state where the piston is in the non-operating position, the piston is provided on the piston and opens to the outer peripheral wall surface of the piston, and communicates with the hydraulic chamber and opens equally to the communication path. A plurality of piston ports arranged in the circumferential direction at the same position in the axial direction can sufficiently secure the passage area and improve the suction performance at the time of brake control not depending on the driver's operation. be able to.

  Further, in the plunger type master cylinder according to the present invention, the piston is stroked from the non-operating position to the hydraulic pressure chamber side by the brake operation by the driver, and the plurality of piston ports are closed by the seal point portion of the seal ring, When the communication between the chamber and the reservoir is interrupted, there is a transition period in which a certain piston port is fully open, some piston ports are partially open and partially closed, and some piston ports are fully closed. is there. Further, the form when the plurality of piston ports are closed by the seal point portion of the seal ring is different for each piston port, and the plurality of piston ports are not simultaneously closed in the same form. For this reason, the reduction of the opening area by all the piston ports changes smoothly between the start of shutoff and the shutoff completion, and a sudden pressure change in the hydraulic chamber is suppressed. Therefore, the uncomfortable feeling given to the driver due to the pressure change in the hydraulic chamber can be suppressed, and the brake feeling can be improved.

It is the vertical side view which showed one Embodiment of the plunger type master cylinder by this invention. It is an expanded sectional view which shows the seal ring shown in FIG. 1, and the structure of the circumference | surroundings. FIG. 2 is a schematic enlarged cross-sectional view of a seal ring and a piston shown in FIG. 1. FIG. 4 is a cross-sectional view of the piston (in a non-actuated position) shown in FIG. FIG. 5 is a cross-sectional view showing a state where the piston shown in FIG. (A) is a seal point portion of the seal ring shown in FIG. 1 to FIG. 5 (endless shape that reciprocates once in the installation area in the axial direction, and the developed shape is V-shaped) in the circumferential direction. (B) is the figure which expand | deployed in the circumferential direction the seal point part (Endless shape which carries out one reciprocation of an installation area | region in an axial direction, and the expand | deployed shape is a curved shape) of deformation | transformation embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a plunger-type master cylinder MC according to the present invention. The master cylinder MC includes a cylinder body 10 assembled to a brake booster (not shown), and pistons 21 assembled to the cylinder body 10. 22, seal rings 31, 32 and 41, 42, and return mechanisms 50, 60 are provided.

  The cylinder body 10 has a cylinder inner hole 11 extending in the axial direction from a closed end (left end in FIG. 1) to an open end (right end in FIG. 1), and is connected to a reservoir R that stores brake fluid. It has a pair of front and rear connection ports 12 and 13. The cylinder body 10 has communication holes 14 and 15 that allow the cylinder inner hole 11 and the connection ports 12 and 13 to communicate with each other, and four wheel cylinders (not shown) via a hydraulic pressure control device (not shown). A pair of front and rear outlet ports 16 and 17 connected to each other.

  A piston (primary piston) 21 on the rear side (opening end side) is pushed forward (on the closed end side) by a brake operation by the driver, and a seal ring 31, A primary fluid pressure chamber Rp1 is defined in front of the seal ring 31 and 41, and an atmospheric pressure fluid chamber Ra1 is formed between the seal rings 31 and 41. The piston 21 is circumferentially arranged at the same axial position so as to open to the outer peripheral wall surface of the piston 21 and to communicate with the primary hydraulic chamber Rp1 and equally open to the rear atmospheric pressure chamber Ra1. A plurality of piston ports 21a are formed. The piston ports 21a are round holes, and 16 are formed at equal intervals in the circumferential direction.

  The primary hydraulic chamber Rp1 is always in communication with the rear outlet port 17, and in the illustrated state (inactive state of the piston 21), it communicates with the atmospheric pressure liquid chamber Ra1 through a piston port 21a provided in the rear piston 21. Since the rear piston 21 moves forward by a predetermined amount from the non-actuated position in the figure and the communication between the piston port 21a and the atmospheric pressure liquid chamber Ra1 is blocked by the seal ring 31, the atmospheric pressure liquid is a hydraulic chamber. The communication with the chamber Ra1 is blocked and sealed. The atmospheric pressure liquid chamber Ra <b> 1 is a hydraulic pressure chamber that always communicates with the rear connection port 13 through the rear communication hole 15, and always communicates with the reservoir R. For this reason, the atmospheric pressure liquid chamber Ra1, the rear communication hole 15, the rear connection port 13 and the like constitute a communication path.

  The seal ring 31 is provided in the annular groove 18 of the cylinder body 10 on the outer periphery of the piston 21. As shown in FIG. 2, the seal ring 31 is primary from the annular base portion 31a and the inner and outer peripheral portions of the base portion 31a. It has a cylindrical inner peripheral lip portion 31b and an outer peripheral lip portion 31c extending toward the hydraulic pressure chamber Rp1 (front).

  The front piston (secondary piston) 22 is pushed forward in accordance with the forward movement of the rear piston 21 and is liquid-tightly connected to the front portion of the cylinder inner hole 11 via the seal rings 32 and 42. The secondary hydraulic pressure chamber Rp2 is defined in front and the atmospheric pressure liquid chamber Ra2 is formed between the seal rings 32 and 42. The piston 22 opens in the outer peripheral wall surface of the piston 22 and communicates with the secondary hydraulic pressure chamber Rp2, and is arranged in the circumferential direction at the same axial position so as to open equally to the front atmospheric pressure liquid chamber Ra2. A plurality of piston ports 22a are formed. The piston ports 22a are round holes, and 16 are formed at equal intervals in the circumferential direction.

  The secondary hydraulic pressure chamber Rp2 is always in communication with the front outlet port 16 and in communication with the atmospheric pressure liquid chamber Ra2 through the piston port 22a provided in the front piston 22 in the illustrated state (inactive state of the piston 22). This is a hydraulic chamber, and the front piston 22 moves forward by a predetermined amount from the non-actuated position in the figure, and the communication between the piston port 22a and the atmospheric pressure liquid chamber Ra2 is blocked by the seal ring 32. The communication with the chamber Ra2 is blocked and sealed. The atmospheric pressure liquid chamber Ra <b> 2 is a hydraulic pressure chamber that always communicates with the front connection port 12 through the front communication hole 14, and always communicates with the reservoir R. For this reason, the atmospheric pressure liquid chamber Ra2, the front communication hole 14, the front connection port 12 and the like constitute a communication path.

  The seal ring 32 is provided in the annular groove 19 of the cylinder body 10 on the outer periphery of the piston 22, and is configured in the same manner as the rear seal ring 31. As shown in FIG. 2, the annular base portion 32a. And a cylindrical inner peripheral lip portion 32b and an outer peripheral lip portion 32c respectively extending from the inner and outer peripheral portions of the base portion 32a toward the secondary hydraulic pressure chamber Rp2 (front).

  The rear return mechanism 50 is for returning the rear piston 21 to the non-operating position shown in FIG. 1, and is provided in the primary hydraulic pressure chamber Rp1, and includes a retainer 51, a stopper 52, a rod 53, and a spring. 54. The retainer 51 is assembled to the rear piston 21. The stopper 52 is engaged with the front piston 31. The rod 53 is fixed to the retainer 51 and is assembled so as to be movable a predetermined amount forward from the illustrated position with respect to the stopper 52. The spring 54 is interposed between the retainer 51 and the stopper 52, the set load in the illustrated state is set to f1, and the rear piston 21 is urged rearward.

  The front return mechanism 60 is for returning the front piston 22 to the non-actuated position shown in FIG. 1 and is provided in the secondary hydraulic pressure chamber Rp2 and includes a spring 64. The spring 64 is interposed between the front wall of the cylinder body 10 and the front piston 22 and urges the front piston 22 rearward.

  The master cylinder MC configured as described above is a hydraulic brake device configured to perform brake control (for example, automatic brake control or traction control for vehicle attitude control) in addition to the brake operation by the driver. Is preferred. In the hydraulic brake device, at the time of brake control not operated by the driver, the brake fluid is supplied from the reservoir R to the hydraulic pressure control device (not shown) through the hydraulic pressure chambers Rp1, Rp2, and the hydraulic pressure control device. (Not shown) is configured to be returned to the reservoir R through the hydraulic chambers Rp1, Rp2.

  By the way, in this embodiment, as shown in FIGS. 1 and 2, when the piston 21 (22) is in the non-actuated position, the inner peripheral lip portion 31b (32b) of the seal ring 31 (32) The front end of an endless seal point portion 31b1 (32b1) that is provided on the circumference and can be sealed with the outer peripheral wall surface of the piston 21 (22) is located closer to the hydraulic chamber Rp1 (Rp2) than the 16 piston ports 21a (22a). The hydraulic chamber Rp1 (Rp2) is connected to the piston port 21a (22a) and the communication path (atmospheric pressure liquid chamber Ra1 (Ra2), communication hole 15 (14), connection port 13 (12), etc.) through the reservoir. It is configured to communicate with R.

  Further, in this embodiment, as shown in FIGS. 2 to 5 and FIG. 6A, the installation area of the seal point portion 31b1 (32b1) in the seal ring 31 (32) has a predetermined axial width W. The seal point portion 31b1 (32b1) is shaped so as to reciprocate once in its axial direction in the axial direction, and the shape developed in the circumferential direction is V-shaped. The predetermined axial width W is set to be the same as the diameter D of each piston port 21a (22a).

  Therefore, in this embodiment, the piston 21 (22) is in the non-actuated position, and the front end of the seal point portion 31b1 (32b1) in the seal ring 31 (32) is the piston port 21a of the piston 21 (22). (22a) is set to the hydraulic chamber side (front). For this reason, the passage area by piston port 21a (22a) can fully be secured, and the suction property at the time of brake control which does not depend on a driver's operation can be made favorable.

  Further, in this embodiment, the piston 21 (22) is stroked forward from the non-actuated position by the brake operation by the driver, and the piston port 21a (22a) is the seal point portion 31b1 (32b1) of the seal ring 31 (32). 4), when the communication between the hydraulic chamber Rp1 (Rp2) and the reservoir R is cut off, as shown in FIG. 4, there is a piston port 21a (22a at the upper end of FIG. 4). Piston port 21a (22a) is in the fully open state (located in the center of FIG. 4) and is partially open and partially closed (located in the lower end of FIG. 4) There is a transition period in which 21a (22a) is fully closed.

  Further, the form when the plurality of piston ports 21a (22a) are closed by the seal point portions 31b1 (32b1) of the seal ring 31 (32) is different for each piston port 21a (22a). The ports 21a (22a) are not simultaneously closed in the same form. For this reason, the reduction of the opening area by all the piston ports 21a (22a) is from the start of shutoff (state of FIG. 3) to the end of shutoff (state of FIG. 5) (that is, the piston 21 (22) is in the non-actuated position. During the stroke from the front side to the front side), the pressure changes smoothly in the hydraulic chamber Rp1 (Rp2). Therefore, the uncomfortable feeling given to the driver due to the pressure change in the hydraulic chamber Rp1 (Rp2) can be suppressed, and the brake feeling can be improved.

  In addition, instead of the seal point portion 31b1 (32b1) of the seal ring 31 (32) described above, when the seal point portion of the seal ring is formed in an annular shape at the same position in the axial direction, all piston ports Since the reduction of the opening area due to 21a (22a) changes while the stroke of the piston 21 (22) is W, and all the piston ports 21a (22a) are simultaneously closed in the same form, the above embodiment is used. In contrast, a rapid pressure change occurs in the hydraulic chamber Rp1 (Rp2).

  In this embodiment, the piston 21 (22) is in the non-operating position so that the rear end of the installation area (W) and the front end of the piston port 21a (22a) overlap each other by a predetermined amount in the axial direction. Therefore, the port idle (piston 21 (22)) is more effective than the case where they are arranged so as to be in contact with each other in the axial direction or the case where these are arranged with a desired amount apart in the axial direction. Is moved forward from the non-actuated position to shorten the piston movement amount until the seal point portion 31b1 (32b1) of the seal ring 31 (32) is seal-coupled to the piston outer wall surface behind the piston port 21a (22a). It is possible to set the invalid stroke of the piston 21 (22) (the piston until the communication between the piston port 21a (22a) and the communication hole 15 (14) is blocked). It is possible to reduce the emissions stroke).

  In the embodiment described above, the shape of the seal point portion 31b1 (32b1) is developed in the circumferential direction so as to reciprocate in the axial direction in the installation area (W) as shown in FIG. However, when carrying out the present invention, it is sufficient that the seal point portion is formed in a shape that reciprocates at least once in the axial direction in the installation region. The shape of the seal point portion 31b1 (32b1) is developed in the circumferential direction so as to reciprocate in the installation area (W) in the axial direction as in the modified embodiment shown in FIG. 6 (b). It is also possible to form and implement so that is a curved shape.

  Moreover, in the said embodiment, although 16 piston ports 21a (22a) provided in piston 21 (22) were implemented, the number of piston ports 21a (22a) can be changed suitably. Moreover, in the said embodiment, although the installation area | region (W) of the seal point part 31b1 (32b1) and the diameter (D) of piston port 21a (22a) were implemented as the same, these are set so that these may differ (for example, diameter ( D) can be set larger or smaller than the installation area (W). In the above embodiment, the piston 21 (22) is in the non-actuated position so that the rear end of the installation region (W) and the front end of the piston port 21a (22a) overlap each other by a predetermined amount in the axial direction. However, it is also possible to arrange them so that they are in contact with each other in the axial direction, or to arrange them so as to be separated by a desired amount in the axial direction.

DESCRIPTION OF SYMBOLS 10 ... Cylinder body, 11 ... Cylinder inner hole, 12, 13 ... Connection port, 14, 15 ... Communication hole, 21, 22 ... Piston, 21a, 22a ... Piston port, 31, 32 ... Seal ring, 31a, 32a ... Base Part, 31b, 32b ... inner peripheral lip part, 31b1, 32b1 ... seal point part, 31c, 32c ... outer peripheral lip part, 50, 60 ... return mechanism, Rp1, Rp2 ... hydraulic pressure chamber, Ra1, Ra2 ... atmospheric pressure liquid chamber , R ... reservoir, W ... setting region (predetermined axial width) of seal point portion, D ... diameter of piston port, MC ... plunger type master cylinder

Claims (2)

A cylinder body having a cylinder bore extending in the axial direction from the closed end portion to the open end portion and having a communication passage for communicating the cylinder bore and the reservoir, and movable in the axial direction to the cylinder bore of the cylinder body A piston that is assembled to form a hydraulic chamber on the closed end side, and an annular base portion that is provided on the cylinder body at the outer periphery of the piston, and the hydraulic pressure from the inner and outer peripheral portions of the base portion, respectively. A seal ring having a cylindrical inner peripheral lip portion and an outer peripheral lip portion extending toward the chamber side, and a return mechanism provided in the hydraulic pressure chamber to return the piston to a non-operating position,
In a state where the piston is in the non-operating position, a front end of an endless seal point portion provided on the inner periphery of the inner peripheral lip portion of the seal ring and capable of being sealed to the outer peripheral wall surface of the piston is connected to the piston. The hydraulic pressure from a plurality of piston ports arranged in the circumferential direction at the same position in the axial direction so as to open to the outer peripheral wall surface of the piston and communicate with the hydraulic pressure chamber and equally open to the communication path A plunger-type master cylinder that is set on the chamber side and is configured such that the hydraulic chamber communicates with the reservoir through the piston port and the communication path;
A plunger type master cylinder in which an installation region of the seal point portion in the seal ring is set with a predetermined axial width, and the seal point portion is formed to reciprocate in the axial direction at least once in the installation region. .   2. The plunger type master cylinder according to claim 1, wherein the shape of the seal point portion developed in the circumferential direction is V-shaped.

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