JP2014221572A - Master cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a master cylinder capable of reducing force by which a piston is pressed against a cylinder hole during piston actuation.SOLUTION: A master cylinder 1 is configured so that: a piston recess part 41 is formed on an opposite side of a bottom part 3a of a cylinder 2 in a state that a piston 4 is inserted into a cylinder hole 3. The piston recess part 41 is formed by exceeding an intersection O of a center line C2 of the piston 4 and a diagonal line L on a cross section including the center line C2 of the piston 4 from a contact point 3b of the piston 4 and the cylinder hole disposed on an opposite side of the bottom part 3a of the cylinder hole 3 .

Description

  The present invention relates to the technical field of master cylinders for brakes and clutches in vehicles such as automobiles.

  2. Description of the Related Art Conventionally, in a hydraulic brake system or a hydraulic clutch system of an automobile, a master cylinder that generates a hydraulic pressure corresponding to the depression force of a brake pedal or a clutch pedal is used to operate a brake or a clutch.

  As the master cylinder, a cylindrical cylinder with a bottom that is closed with one side being an open end and the other side being a bottom, and the cylinder is slidably fitted into the cylinder, and the inside of the cylinder is axially moved according to a brake operation. Displaceable first and second pistons, a first hydraulic chamber defined in the cylinder between the first and second pistons, and between the bottom of the cylinder and the second piston And the second hydraulic chamber defined in the cylinder and the first piston disposed between the first and second pistons located in the first hydraulic chamber. A first return spring that urges toward the opening end side of the cylinder, and a second return piston that is disposed between the bottom of the cylinder and the second piston and is located in the second hydraulic pressure chamber. A second return spring biasing toward the first piston, and the first and second pistons A plurality of seal members respectively provided in the cylinder for sealing between the cylinder and the cylinder, and the first and second hydraulic pressure chambers are connected to the wheel cylinder on the wheel side via the first and second fail-safe valves. There is known a master cylinder that includes first and second brake pipes that are connected to each other and a stroke simulator that generates a brake reaction force during brake operation (see, for example, Patent Document 1).

  FIG. 6 is a schematic view showing a conventional cylinder and a primary piston. FIG. 7 is an enlarged schematic view of a part of FIG.

  A primary piston 4 'is inserted into the cylinder hole 3' of the cylinder 2 '. In general, the cylinder 2 ′ and the primary piston 4 ′ are assembled so as to be concentric, and the primary piston 4 ′ is set to slide in the cylinder hole 3 ′. However, in practice, as shown in FIGS. 5 and 6, the center line C1 ′ of the cylinder hole 3 ′ and the center line C2 ′ of the primary piston 4 ′ do not completely overlap, and a slight deviation occurs. There is.

  When the center line C1 ′ of the cylinder hole 3 ′ and the center line C2 ′ of the primary piston 4 ′ are shifted by an angle θ ′, as shown in FIG. 5, a part of the corner 40 ′ of the primary piston 4 ′ It abuts on the cylinder hole 3 ′ at the abutment point 3b ′. When the booster operates in this state, the primary piston 4 'is pressed with the force P' by the force point 41a 'of the piston recess 41' by a push rod 30 'of the booster (not shown).

  The conventional primary piston 4 ′ shown in FIGS. 6 and 7 is a cross section including the center line C1 ′ of the cylinder hole 3 ′ and the center line C2 ′ of the primary piston 4 ′ or the center line C2 ′ of the primary piston 4 ′. A piston recess 41 'is formed on the booster side of the intersection O' with the diagonal line L '. Therefore, the force point 41a ′ of the primary piston 4 ′ pressed by the push rod 30 ′ is also present on the booster side of the intersection O ′ between the center line C1 ′ of the cylinder hole 3 ′ and the center line C2 ′ of the primary piston 4. .

  In this case, when the force point 41a ′ of the piston recess 41 ′ is pressed with the pressing force P ′ by the push rod 30 ′, the direction in which the pressing force P acts does not pass on the intersection point O ′ as shown in FIG. As a result of the offset, a moment M ′ about the intersection O ′ is generated. Then, by the moment M ′, as shown in FIG. 6, a pressing force F ′ acts from the primary piston 4 ′ to the contact point 3 b ′ of the cylinder hole 3 ′.

  For example, as shown in FIG. 6, when the length from the intersection point O ′ to the force point 41a ′ is B ′, the offset amount h ′ shown in FIG. 7 is h ′ = B′sin θ ′. The moment M ′ is M ′ = h′p ′, and the pressing force F ′ is F ′ = M ′ / A ′.

Japanese Patent No. 4589358

  Therefore, in the invention described in Patent Document 1, when the primary piston is pressed by the push rod, a pressing force acts on the contact point of the cylinder hole from the primary piston, and the primary piston and the cylinder are worn. was there.

  This invention is made | formed in view of such a situation, The objective is to provide the master cylinder which reduces the force by which a piston is pressed by a cylinder hole at the time of piston operation.

In order to solve the above-mentioned problem, the master cylinder according to the present embodiment is
A cylinder having a cylinder hole formed with a bottom, and
A piston defining a hydraulic chamber slidably inserted into the cylinder hole;
A communication path that is provided in the cylinder and communicates with a reservoir; a relief port that is formed in the piston and communicates with the hydraulic pressure chamber at all times and communicates with the communication path and the hydraulic pressure chamber;
A seal member that is accommodated in a recess in the inner peripheral surface of the cylinder hole and that slidably penetrates the piston to seal between the inner peripheral surface of the cylinder hole and the outer peripheral surface of the piston;
With
In the master cylinder in which the communication path and the relief port communicate with each other during non-operation, and the piston moves during operation and the communication path and the relief port are blocked by the seal member,
In the state where the piston is inserted into the cylinder hole, a piston recess is formed on the side opposite to the bottom of the cylinder,
The piston recess has an intersection of a center line of the piston and a diagonal line in a cross section including the center line of the piston from a contact point between the piston disposed on the opposite side of the bottom of the cylinder hole and the cylinder hole. It is characterized by being formed beyond.

The master cylinder according to this embodiment is
The piston recess is formed such that the length from the end of the cylinder hole opposite to the bottom increases as the distance from the center line of the piston approaches.

The master cylinder according to this embodiment is
The center line of the cylinder hole and the center line of the piston intersect with each other with a predetermined angle.

Furthermore, the brake device according to the present embodiment is
The master cylinder;
A booster having a push rod for pressing the piston recess;
It is characterized by providing.

  According to the present invention, in the master cylinder, when the piston is inserted into the cylinder hole, the piston recess is formed on the side opposite to the bottom of the cylinder, and the piston recess is disposed on the side opposite to the bottom of the cylinder hole. It is formed beyond the intersection of the piston center line and the diagonal line in the cross section including the piston center line from the contact point between the piston and the cylinder hole, reducing the force with which the piston is pressed against the cylinder hole during piston operation A master cylinder can be provided.

  Further, in the master cylinder according to the present embodiment, the piston recess is formed so that the length from the end opposite to the bottom of the cylinder hole becomes longer as it approaches the center line of the piston. It is possible to accurately determine the pressed position.

  Further, in the master cylinder according to the present embodiment, the center line of the cylinder hole and the center line of the piston intersect with each other at a predetermined angle, so that a force that separates the piston from the cylinder hole is applied when the piston is operated. Therefore, it is possible to provide a master cylinder that operates accurately, has little wear, and has a long life.

  Furthermore, the brake device according to the present embodiment includes a master cylinder and a booster device having a push rod that presses the piston recess, so that the brake device that operates properly and has little wear and long life is provided. Is possible.

It is a figure which shows one Embodiment of the master cylinder which concerns on this invention. It is the schematic which shows the cylinder and primary piston of this embodiment. FIG. 3 is an enlarged schematic view of a part of FIG. It is the schematic which shows the state after the action | operation of the cylinder and primary piston of this embodiment. It is an example of the brake device using the master cylinder of this embodiment. It is the schematic which shows the conventional cylinder and a primary piston. It is the schematic which expanded a part of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a master cylinder according to the present invention.

  As shown in FIG. 1, the master cylinder 1 includes a cylinder 2, and a cylinder hole 3 is formed in the cylinder 2.

A primary piston 4 as an example of the piston of the present embodiment and a secondary piston 5 as an example of the piston of the present embodiment are slidably inserted into the cylinder hole 3.
The primary piston 4 is pressed by a push rod 30 such as a brake pedal (not shown) or a brake booster that boosts and outputs the depressing force of the brake pedal, and moves to the left in the drawing. By the primary piston 4 and the secondary piston 5, the first hydraulic pressure chamber 6 is defined between the primary piston 4 and the secondary piston 5 in the cylinder hole 3, and the second hydraulic pressure chamber 8 is the secondary piston. 5 and a bottom portion 3 a of the cylinder hole 3.

  A shaft member 7 is disposed in the first hydraulic pressure chamber 6, and a pair of left and right first and second retainers 9, 10 are provided on the shaft member 7. Although the second retainer 10 is fixed to the shaft member 7, the first retainer 9 is slidable on the shaft member 7. In this case, the first retainer 9 is in contact with a latching portion 7a formed at the right end of the shaft member 7, so that the first and second retainers 9, 10 are set in a state of being maximally separated from each other as shown in FIG. The A first return spring 11 is contracted between the first and second retainers 9 and 10. The first retainer 9 is always in contact with the primary piston 4 and the second retainer 10 is always in contact with the secondary piston 5, and when the master cylinder 1 shown in FIG. Are set to a state of maximum separation.

  The second hydraulic chamber 8 is provided with a pair of left and right third and fourth retainers 12 and 13. The third retainer 12 is slidable on the fourth retainer 13. In that case, the 3rd and 4th retainers 12 and 13 are set to the state mutually spaced apart to the maximum shown in FIG. A second return spring 14 is contracted between the third and fourth retainers 12 and 13. The third retainer 12 is always in contact with the secondary piston 5 and the fourth retainer 13 is always in contact with the bottom 3a of the cylinder hole 3. When the master cylinder 1 is not in operation, the secondary piston 5 is maximum from the bottom 3a. Are set apart from each other.

  The cylinder 2 is provided with a reservoir 29. The reservoir 29 can be communicated with the first hydraulic chamber 6 via a first relief port 16 formed in the first communication passage 15 and the primary piston 4 and constantly communicating with the first hydraulic chamber 6. The first relief port 16 is drilled in the left end side tubular portion 4 a of the primary piston 4 and communicates the first hydraulic chamber 6 on the inner peripheral side of the primary piston 4 and the first communication passage 15 on the outer peripheral side. It is composed of directional communication holes. The reservoir 29 can communicate with the second hydraulic pressure chamber 8 via the second communication passage 17 and the second relief port 18 formed in the secondary piston 5. Similar to the first relief port 16, the second relief port 18 is also formed in the cylindrical portion 5 a of the secondary piston 5, and the second hydraulic chamber 8 on the inner peripheral side of the secondary piston 5 and the second communication chamber on the outer peripheral side. It is comprised from the communicating hole of the radial direction which connects the channel | path 17.

  FIG. 2 is a schematic view showing a cylinder and a primary piston of the present embodiment. FIG. 3 is an enlarged schematic view of a part of FIG.

  In the master cylinder 1 of the present embodiment, a primary piston 4 is inserted into the cylinder hole 3 of the cylinder 2. In the state where the primary piston 4 is inserted into the cylinder hole 3, a piston recess 41 is formed on the side opposite to the bottom 3a of the cylinder 2, and the piston recess 41 has an end 42 on the side opposite to the bottom 3a, particularly the primary piston. 4 and a contact point 3b between the cylinder hole 3 and an intersection point O between the center line C1 of the cylinder hole 3 and the center line C2 of the primary piston 4. Therefore, the force point 41a of the primary piston 4 pressed by the push rod 30 is also on the opposite side of the booster from the intersection O of the center line C1 of the cylinder hole 3 and the center line C2 of the primary piston 4.

  Further, the piston concave portion 41 is formed such that the length from the end portion 42 on the opposite side to the bottom portion 3a of the cylinder hole 3 becomes longer as it approaches the center line C2 of the primary piston 4.

  As described above, the cylinder 2 and the primary piston 4 are assembled so as to be concentric, and the primary piston 4 is set to slide in the cylinder hole 3. In practice, however, as shown in FIGS. 2 and 3, the center line C1 of the cylinder hole 3 and the center line C2 of the primary piston 4 do not completely overlap, and some deviation may occur. That is, the center line C1 of the cylinder hole 3 and the center line C2 of the primary piston 4 intersect with a predetermined angle.

  When the center line C1 of the cylinder hole 3 and the center line C2 of the primary piston 4 are shifted by an angle θ, as shown in FIG. 2, a part of the corner portion 40 of the primary piston 4 is in contact with the cylinder hole 3 and the contact point 3b. Abut. When the booster is actuated in this state, the primary piston 4 is pressed with the force P on the force point 41a of the piston recess 41 by the push rod 30 of the booster (not shown).

  When the force point 41a of the piston recess 41 is pressed with the pressing force P by the push rod 30, the direction in which the pressing force P acts is offset without passing over the intersection point O as shown in FIG. A moment M about the intersection O is generated. Then, due to the moment M, a separation force F acts on the primary piston 4 so as to be away from the contact point 3b of the cylinder hole 3 as shown in FIG.

  For example, as shown in FIG. 2, if the length from the intersection point O to the force point 41a is B, the offset amount h shown in FIG. 3 is h = Bsinθ. The moment M is M = hp, and the separation force F is F = M / A.

  Thus, in the primary piston 4 of the present embodiment, the intersection O between the center line C1 of the cylinder hole 3 and the center line C2 of the primary piston 4 from the booster device side to the opposite side of the booster device. Formed beyond. The primary piston 4 is pressed by the pressing force P against the force point 41 a of the piston recess 41 by the push rod 30. For this reason, the separation force F acts on the primary piston 4 so as to move away from the contact point 3b of the cylinder hole 3 by the moment M generated around the intersection point O.

  FIG. 4 is a schematic view showing a state after the operation of the cylinder and the primary piston of the present embodiment.

  As shown in FIG. 4, when the primary piston 4 is pressed by the push rod 30, a separation force F acts on the primary piston 4 so as to move away from the contact point 3 b of the cylinder hole 3.

  And since the piston recessed part 41 is formed so that the length from the edge part 42 on the opposite side to the bottom part 3a of the cylinder hole 3 may become so long that it approaches the centerline C2 of the primary piston 4, push rod 30 Will press the force point 41a of the piston recess 41 with the force P, and the center line C1 of the cylinder hole 3 and the center line C2 of the primary piston 4 will almost overlap.

  Therefore, when the primary piston 4 is pressed by the push rod 30, the primary piston 4 and the cylinder hole 3 are separated from each other, and wear of the primary piston 4 and the cylinder hole 3 can be reduced.

  FIG. 5 is an example of a brake device using the master cylinder of this embodiment. In the following description, “front” and “rear” indicate “left” and “right” in each figure, respectively.

  In FIG. 5, 51 is a negative pressure booster, 52 is a front shell, 53 is a rear shell, 54 is a valve body, 55 is a power piston member 56 attached to the valve body 54 and formed of a material such as an aluminum-based metal. A power piston 58, which is provided between the valve body 54 and the shells 52, 53 and is formed of a diaphragm 57 formed of a member having a lot of elastic deformation, the space in the shells 52, 53 is hermetically partitioned by the power piston 55. One of the two chambers is a constant pressure chamber into which negative pressure is normally introduced, 59 is the other of the two chambers described above, and a variable pressure chamber into which atmospheric pressure is introduced when the negative pressure booster 51 is operated, 60 is a valve A plunger 61 is connected to a brake pedal, which is an operating member (not shown), and an input shaft 62 that controls the operation of the valve plunger 60. 62 is provided in the valve body 54. Body, 63 is a negative pressure valve composed of the valve body 54 and the valve body 62, 64 is an atmospheric valve composed of the valve plunger 60 and the valve body 62, 65 is an atmospheric inflow passage formed in the valve body 54, 66 is a negative pressure introduction passage that communicates the constant pressure chamber 58 and the variable pressure chamber 59, and 67 is a place where the relative movement of the valve plunger 60 with respect to the valve body 54 is defined by the axial width of the key hole formed in the valve body 54. A key member that regulates the amount and regulates each retreat limit of the valve body 54 and the valve plunger 60, 68 is a spacing member that constitutes a part of the reaction force means, and 69 is a reaction disk that constitutes the other part of the reaction force means. , 71 is a return spring for returning the power piston 55 and the valve body 54 to the non-operating position, and 72 is a negative pressure inlet.

  Next, the operation of the negative pressure booster 51 and the brake system 24 of this example will be described.

  When the brake is not operated, the negative pressure booster 51 has the input shaft 61 in the backward limit position. Further, a predetermined negative pressure is introduced into the normal time constant pressure chamber 68 through the negative pressure introduction port 72. When the negative pressure booster 51 is in an inoperative state, the negative pressure valve 63 is open and the atmospheric valve 64 is closed. Therefore, the constant pressure chamber 58 and the variable pressure chamber 59 communicate with each other through the negative pressure introduction passage 66, and the variable pressure chamber 59 is shut off from the atmosphere. As a result, negative pressure is also introduced into the variable pressure chamber 59.

  When a brake pedal (not shown) is depressed, the input shaft 61 moves forward and the valve plunger 60 moves forward. Then, the negative pressure valve 63 is closed and the atmospheric valve 64 is opened. As a result, the constant pressure chamber 58 and the variable pressure chamber 59 are blocked, and the variable pressure chamber 59 communicates with the air introduction passage 65. Accordingly, air (air) is introduced into the variable pressure chamber 59, and a pressure difference is generated between the variable pressure chamber 59 and the constant pressure chamber 58. Due to this pressure difference, the power piston 55 moves forward against the urging force of the return spring 71, the valve body 54, the reaction disk 69, and the push rod 30 move forward, and the negative pressure booster 51 operates. As the push rod 30 moves forward, the piston of the master cylinder 1 operates to generate a hydraulic pressure, and a brake cylinder (not shown) generates a braking force by this hydraulic pressure, and each wheel is braked.

  When the depression of a brake pedal (not shown) is released, the input shaft 61 moves backward, and the negative pressure valve 63 is opened and the atmospheric valve 64 is closed. Then, the air introduced into the variable pressure chamber 59 flows into the constant pressure chamber 58 through the negative pressure valve 63 and the negative pressure introduction passage 66, and the air that has flowed into the constant pressure chamber 58 flows out of the constant pressure chamber 58 through the negative pressure introduction port 72. To do. As a result, the pressure in the variable pressure chamber 59 is reduced, and the power piston 55, push rod 30, valve body 54, reaction disk 69, spacing member 68, and valve plunger 60 are retracted by the urging force of the return spring 71. Then, the piston of the master cylinder 1 also moves backward, and the hydraulic pressure in the master cylinder 1 gradually decreases and disappears. Then, the key body 67 restricts the valve body 54 and the valve plunger 60 to the retreat limit position, the negative pressure booster 51 is deactivated, and the brakes of the wheels are released.

  Also in such a brake device, in the primary piston 4, the intersection O between the center line C <b> 1 of the cylinder hole 3 and the center line C <b> 2 of the primary piston 4 from the booster device side to the opposite side of the booster device. Since the primary piston 4 is pressed by the push rod 30 with the pressing force P by the push rod 30, the contact point 3b of the cylinder hole 3 is caused by the moment M generated around the intersection O. A separation force F acts on the primary piston 4 so as to be separated from the primary piston 4.

  Therefore, when the primary piston 4 is pressed by the push rod 30, the separation force F acts on the primary piston 4 so as to move away from the contact point 3 b of the cylinder hole 3, thereby reducing wear of the primary piston 4 and the cylinder hole 3. It becomes possible.

  The master cylinder according to the present invention is not limited to the master cylinder of the brake device, and any master cylinder may be used as long as it generates hydraulic pressure in the hydraulic chamber by the advance of the piston, including the master cylinder of the clutch device. The present invention can also be applied to such a hydraulic device. Further, in the example described above, the two pistons are described tandem master cylinders arranged in series, if the plunger-type master cylinder, to any master cylinder begin single master cylinder, of the present invention A master cylinder can be applied.

DESCRIPTION OF SYMBOLS 1 ... Master cylinder, 2 ... Cylinder, 3 ... Cylinder hole, 3a ... Bottom part, 4 ... Primary piston, 5 ... Secondary piston, 6 ... 1st hydraulic pressure chamber, 7 ... Shaft member, 8 ... 2nd hydraulic pressure chamber, 9 ... 1st retainer, 10 ... 2nd retainer, 11 ... 1st return spring, 12 ... 3rd retainer, 13 ... 4th retainer, 14 ... 2nd return spring, 15 ... 1st communicating path, 16 ... 1st relief port 17 ... 2nd communicating path, 18 ... 2nd relief port, 19 ... 1st recessed part, 19a ... Base part side wall, 19b ... Bottom wall, 19c ... Lip part side wall, 19d ... Tapered part, 20 ... 1st sealing member, 20a ... Base part, 20b ... Inner lip part, 20c ... Outer lip part, 20d ... Intermediate lip part, 20e ... Base part side groove, 20f ... Lip part side groove, 21 ... Second recess, 22 ... Second seal member, 2 ... 1st output port, 24 ... 2nd output port, 25 ... 1st sealing seal recessed part, 26 ... 1st sealing seal, 27 ... 2nd sealing seal recessed part, 28 ... 2nd sealing seal, 29 ... Reservoir, 30 ... push rod, 40 ... corner, 41 ... piston recess, 42 ... end

Claims (4)

A cylinder having a cylinder hole formed with a bottom, and
A piston defining a hydraulic chamber slidably inserted into the cylinder hole;
A communication path that is provided in the cylinder and communicates with a reservoir; a relief port that is formed in the piston and communicates with the hydraulic pressure chamber at all times and communicates with the communication path and the hydraulic pressure chamber;
A seal member that is accommodated in a recess in the inner peripheral surface of the cylinder hole and that slidably penetrates the piston to seal between the inner peripheral surface of the cylinder hole and the outer peripheral surface of the piston;
With
In the master cylinder in which the communication path and the relief port communicate with each other during non-operation, and the piston moves during operation and the communication path and the relief port are blocked by the seal member,
In the state where the piston is inserted into the cylinder hole, a piston recess is formed on the side opposite to the bottom of the cylinder,
The piston recess has an intersection of a center line of the piston and a diagonal line in a cross section including the center line of the piston from a contact point between the piston disposed on the opposite side of the bottom of the cylinder hole and the cylinder hole. A master cylinder characterized by being formed beyond. The said piston recessed part is formed so that the length from the edge part on the opposite side to the said bottom part of the said cylinder hole may become so long that it approaches the centerline of the said piston. Master cylinder. 3. The master cylinder according to claim 1, wherein a center line of the cylinder hole and a center line of the piston intersect with each other at a predetermined angle. A master cylinder according to any one of claims 1 to 3,
A booster having a push rod for pressing the piston recess;
A brake device comprising:

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