JP2018144644A - Brake booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake booster that is highly practical.SOLUTION: A brake booster comprises a valve mechanism that allows introduction of atmosphere into a pressure change chamber 22 as a result of separation of a portion 84 functioning as a valve body of each of input rods 12, 60 from a valve seat 82 due to forward movement of each input rod 12, 60, and that inhibits introduction of atmosphere into the pressure change chamber 22 as a result of seating of the portion 84 functioning as the valve body on the valve seat 82 due to backward movement of each input rod 12, 60. A pair of magnets 90, 92 for causing repulsion are respectively provided for the portion 84 functioning as the valve body and the valve seat 82. According to this brake booster 10, characteristics for the valve mechanism that allows communication between the pressure change chamber 22 and atmosphere and disconnection of them can be set in a combination of the characteristics of the elastic forces of return springs 102, 106 and the characteristic of repulsion of the pair of magnets 90, 92.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a brake booster that assists the operating force of a brake operation.

  The following Patent Document 1 discloses a brake that assists the operating force of a brake operation using a differential pressure between a negative pressure chamber into which a negative pressure generated in an intake pipe of an engine is introduced and a variable pressure chamber into which air is introduced. The booster is listed. In the state where the brake operation is not performed, the brake booster is set so that the pressure in the variable pressure chamber is equal to the pressure in the negative pressure chamber and is not operated. Then, an operating force is applied to the brake operating member, and the valve mechanism is opened and air is introduced into the variable pressure chamber as the input rod moves forward in conjunction with the operation of the brake operating member. And a differential pressure chamber.

JP 2008-168724 A

  In the above brake booster, when a certain braking force is to be maintained, even if the operation of the brake operating member is stopped, the pressure in the variable pressure chamber is not maintained until the valve mechanism for communicating / blocking the variable pressure chamber and the atmosphere is closed. May change. The change in pressure in the variable pressure chamber after the operation of the brake holding member stops is problematic because it affects the operation feeling of the brake operation. For example, it is considered that the deterioration of the operation feeling can be suppressed by increasing the force for closing the valve mechanism that communicates and shuts off the variable pressure chamber and the atmosphere, thereby speeding up the valve closing. However, the force in the direction to close the valve mechanism that communicates and shuts off the variable pressure chamber and the atmosphere includes the biasing force of the return spring that biases the input rod in the backward direction. Therefore, if the urging force of the return spring is increased to increase the force in the direction for closing the valve mechanism, the operation load of the brake operation is increased. The present invention has been made in view of such a situation, and it is considered that the practicality of the brake booster can be improved by dealing with such a problem. Therefore, an object of the present invention is to provide a brake booster with high practicality.

  In order to solve the above-described problems, the brake booster according to the present invention allows the air rod to be introduced into the variable pressure chamber by allowing the portion that functions as the valve body of the input rod to move away from the valve seat as the input rod advances. The part that functions as the valve body of the input rod is seated on the valve seat by retreating the valve and has a valve mechanism that prohibits the introduction of air into the variable pressure chamber, generating repulsive force on each part of the input rod and the valve seat A pair of magnets is provided.

  According to the brake booster of the present invention, it is possible to set the characteristics of the valve mechanism for communicating / blocking the variable pressure chamber and the atmosphere in combination with the characteristics of the elastic force of the return spring and the characteristics of the repulsive force of the magnet. . For example, even if the set load of the return spring is increased and the force for closing the valve mechanism by the return spring is increased, the repulsive force increases in a curve as the magnet of the same magnetic pole approaches, The load when operating the brake operation member can be reduced. That is, according to the brake booster of the present invention, it is possible to improve the valve closing speed of the valve mechanism that communicates and shuts off the variable pressure chamber and the atmosphere while maintaining the operability of the brake operation member. is there.

It is a side view (partial sectional view) of a brake booster which is an embodiment of the present invention. It is sectional drawing of the power piston with which the brake booster shown in FIG. 1 is provided. It is a figure which expands and shows the inside of a power piston for the action | operation of the brake booster of a present Example. It is the figure which showed the relationship between the stroke of the brake operation member in the conventional brake booster, and the treading force added to the brake operation member. It is a figure which shows the characteristic of the air valve shown in FIG.

  Hereinafter, as an embodiment for carrying out the present invention, an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following Example, It can implement in the various aspect which gave various change and improvement based on the knowledge of those skilled in the art.

  The brake booster 10 according to the embodiment of the present invention assists the driver's operation force input from the brake operation member connected to the operating rod 12 by using the negative pressure of the engine. This is a so-called vacuum booster that outputs to the vacuum. In the following description, the movement of the operating rod 12 and the push rod 14 when the brake operating member is depressed is called forward, and the movement of the operating rod 12 and the push rod 14 when the brake operating member is returned is called backward. The side on which the rods are advanced (left side in FIG. 1) may be referred to as the front side, and the side on which the rods are retracted (right side in FIG. 1) is referred to as the rear side.

  As shown in FIG. 1, the brake booster 10 includes a housing 24 in which two pressure chambers 20 and 22 are formed, and a valve portion 26 that adjusts the pressure in the housing 24. The housing 24 is partitioned by a diaphragm 28 into a negative pressure chamber 20 that is a pressure chamber on the front side of the diaphragm 28 and a variable pressure chamber 22 that is a pressure chamber on the rear side. The negative pressure chamber 20 is connected to the intake pipe of the engine via the check valve 30 so that supply of negative pressure is allowed.

  The valve portion 26 includes the operating rod 12 and the push rod 14 described above, and a power piston 40 that is slidably held in the front-rear direction on the rear side of the housing 24. As for the power piston 40, the inner peripheral part of said diaphragm 28 is being fixed to the outer peripheral surface of the front-end part. The power piston 40 is urged toward the rear side by a compression coil spring 42 provided in the negative pressure chamber 20 of the housing 24.

  As shown in FIG. 2, the power piston 40 is generally cylindrical. The power piston 40 has a first communication hole 52 that allows the interior of the power piston 40 to communicate with the negative pressure chamber 20, and a second communication hole 54 that allows the interior of the power piston 40 to communicate with the variable pressure chamber 22. On the front side of the power piston 40, the push rod 14 accommodates a rubber disc-like reaction disk 50 at the rear end thereof, and the reaction disk 50 opens an opening on the front side of the power piston 40. It is held like a block.

  Inside the power piston 40, a reaction rod 60 is fitted on the front end side so as to be slidable in the front-rear direction. The reaction rod 60 is formed in a cylindrical shape on the rear side, and the front end of the operating rod 12 is inserted and connected. That is, the reaction rod 60 is moved forward and backward together with the operating rod 12 by the driver's braking operation, and it can be considered that the reaction rod 60 and the operating rod 12 constitute an input rod. The reaction rod 60 is positioned rearward from the reaction disk 50 in a state where the brake operation is not performed. When the reaction rod 60 is advanced, the tip of the reaction rod 60 comes into contact with the reaction disk 50, and the push rod 14 is advanced through the reaction disk 50. As the push rod 14 moves forward, the power piston 40 is also moved forward.

  A control valve 70 is fitted inside the power piston 40 so as to be slidable in the front-rear direction. The control valve 70 is cylindrical and has an annular flange portion 72 extending inward at the front end. An annular rubber 74 is attached to the front surface of the flange portion 72. When the control valve 70 is moved forward, the flange portion 72 comes into contact with a stepped portion 76 formed inside the power piston 40 via the rubber 74. In this state, the opening of the first communication hole 52 is blocked. An annular valve seat member 82 having an annular rubber 80 attached to the front surface is fixed to the rear end of the control valve 70. The valve seat member 82 is provided so that the front surface thereof faces the back surface of the flange 84 formed at the rear end of the reaction rod 60. The valve seat member 82 and the flange 84 can be brought into contact with each other via the rubber 80.

  An annular magnet 90 is attached to the valve seat member 82 on the inner peripheral side from the rubber 80. In addition, an annular magnet 92 is attached to the rear surface of the flange 84 of the reaction rod 60. The magnet 90 of the valve seat member 82 and the magnet 92 of the reaction rod 60 are of the same magnetic pole (S pole) and are provided so as to face each other. Therefore, a force in a direction away from each other acts between the reaction rod 60 and the valve seat member 82 due to the repulsive force of the two magnets 90 and 92. That is, due to the repulsive force of these two magnets 90 and 92, a force directed toward the front acts on the reaction rod 60, that is, the operating rod 12, and a force directed toward the rear acts on the valve seat member 82. The effects of these two magnets 90 and 92 will be described in detail later.

  Further, an annular spring receiving member 100 is slidably inserted into the power piston 40. A compression coil spring 102 is disposed between the back surface of the valve seat member 82 and the spring receiving member 100, and a return is provided between the spring receiving member 100 and the spring seat 104 fixed to the operating rod 12. A compression coil spring 106 is disposed as a spring. The valve seat member 82 and the control valve 70 are biased forward by the spring 102, and the operating rod 12 is biased backward by the spring 106.

  Furthermore, a filter 110 is disposed at the rear end of the power piston 40 so as to close the opening on the rear side. Inside the power piston 40, the atmosphere flows through the filter 110. At this time, the filter 110 prevents dust and dirt in the atmosphere from entering the power piston 40. The Between the valve seat member 82 and the spring receiving member 100, a seal member 112 that can be expanded and contracted in the front-rear direction is provided, and the air that has flowed into the power piston 40 flows between the outer peripheral surface of the control valve 70 and the power piston 40. It is prevented that it flows between the inner peripheral surfaces of the.

  The operation of the brake booster 10 configured as described above will be described with reference to FIG. First, in a state where the driver does not perform the brake operation, as shown in FIG. 3A, the power piston 40 is positioned on the rear end side by the spring 42, and the operating rod 12 and the reaction rod 60 are The spring 106 is positioned on the rear end side. Further, the control valve 70 and the valve seat member 82 are biased forward by the spring 102, and the valve seat member 82 is brought into contact with the flange 84. Although repulsive force is generated by the magnets 90 and 92 between the valve seat member 82 and the flange 84, the elastic force of the spring 102 is made larger than the repulsive force by the magnets 90 and 92 as shown in FIG. Therefore, the valve seat member 82 can be brought into contact with the flange 84.

  In the state where the valve seat member 82 is in contact with the flange 84, the inside of the power piston 40 is partitioned into the space 120 on the front side and the space 120 on the rear side by the valve seat member 82 and the reaction rod 60. become. The atmosphere flows into the rear space 122 through the filter 110, but the inflow of air into the front space 120 is blocked.

  Further, when the reaction rod 60 is located on the rear end side and the valve seat member 82 is in contact with the flange 84, the control valve 70 is not in contact with the stepped portion 76, and the front space 120. Is in a state of communicating with the negative pressure chamber 20 through the first communication hole 52. The space 120 on the front side is always in communication with the variable pressure chamber 22 through the second communication hole 54. That is, the negative pressure chamber 20 and the variable pressure chamber 22 are in communication with each other in a state where they are cut off from the atmosphere, and are in a negative pressure and equal pressure state. In this state, the reaction rod 60 is in a state where the tip is separated from the reaction disk 50 to the rear side.

  When the driver depresses the brake operation member and the operating rod 12 and the reaction rod 60 are advanced, first, the driver moves forward relative to the power piston 40, and the reaction rod 60 contacts the reaction disc 50. . Then, the operating rod 12 and the reaction rod 60 move forward together with the power piston 40, that is, move forward together with the push rod 14 while elastically deforming the reaction disk 50.

  As described above, when the reaction rod 12 moves forward, the valve seat member 82 and the control valve 70 that are in contact with the reaction rod 12 are also urged forward by the spring 102, and therefore move forward. Then, as shown in FIG. 3B, the control valve 70 abuts on the stepped portion 76 and the forward movement relative to the power piston 40 is stopped. As the operating rod 12 and the reaction rod 60 are further advanced, the operating rod 12 and the reaction rod 60 are advanced relative to the control valve 70 and the valve seat member 82, and the flange 84 of the reaction rod 60 is moved to the valve seat member 82. It is separated from.

  Since the control valve 70 is brought into contact with the stepped portion 76, the negative pressure chamber 20 and the space 120 on the front side are blocked. Further, since the flange 84 is separated from the valve seat member 82, the front space 120 and the rear space 120 are in communication with each other. That is, when the brake operation member is depressed by the driver, the negative pressure chamber 20 and the variable pressure chamber 22 are blocked, and the variable pressure chamber 22 is in communication with the atmosphere. In this state, the negative pressure chamber 20 has a negative pressure, whereas the variable pressure chamber 22 approaches the atmospheric pressure, so that a differential pressure is generated between the negative pressure chamber 20 and the variable pressure chamber 22, and the differential pressure is generated. A force based on the above acts on the power piston 40 via the diaphragm 28. Since the force based on the differential pressure is a force in the direction of moving the power piston 40 forward, the operating force applied to the operating rod 12 by the driver is assisted.

  From the above configuration, the flange 84 of the reaction rod 60 functions as a valve body, and the valve seat member 82 functions as a valve seat. The reaction rod 60 and the valve seat member 82 are included, and the variable pressure chamber 22 communicates with the atmosphere. -An air valve, which is a valve mechanism that shuts off, is configured. Further, the control valve 70 functions as a valve body and the stepped portion 76 functions as a valve seat, and includes the control valve 70 and the stepped portion 76 to communicate and block the negative pressure chamber 20 and the variable pressure chamber 22. A vacuum valve is configured.

  Next, consider a case where the driver stops the depression of the brake operation member, in other words, a case where the driver holds the brake operation member in a state where the brake operation member is depressed to some extent. In such a case, the forward movement of the operating rod 12 and the reaction rod 60 is stopped, whereas the power piston 40 is subjected to a force based on the above-described differential pressure between the negative pressure chamber 20 and the variable pressure chamber 22. Therefore, it is moved forward. Accordingly, the valve seat member 82 is brought into contact with the flange 84, and the front space 120 and the rear space 120 are blocked. In this case, the control valve 70 is in contact with the stepped portion 76. Therefore, the negative pressure chamber 20 and the variable pressure chamber 22 are blocked, and the variable pressure chamber 22 is blocked from the atmosphere. Thereby, since the pressure change of the variable pressure chamber 22 stops, the advance of the power piston 40 also stops.

  As described above, even if the depression of the brake operation member is stopped, the increase in the assist force of the brake operation by the brake booster 10 is not stopped until the variable pressure chamber 22 is shut off from the atmosphere. Actually, since the driver stops the depression of the brake operation member, the driver feels not as an increase in the assist force for the brake operation but as a decrease in the reaction force against the brake operation member. That is, in the conventional brake booster, as shown in FIG. 4, there is a problem that the pedal force applied to the brake must be reduced in order to maintain the brake depression amount.

  In order to cope with this problem, the brake booster 10 has a characteristic that the air valve has a spring 102 disposed between the valve seat member 82 and the spring receiving member 100, as shown by a solid line in FIG. The elastic force of the spring 106 disposed between the spring receiving member 100 and the operating rod 12 (specifically, the spring seat 104), and the magnet provided on each of the flange 84 and the valve seat member 82 of the reaction rod 60. 90 and 92 repulsive forces are set in combination.

  In this brake booster 10, first, the set load of the spring 102 and the spring 106 is set to a value larger than the set load of the return spring in the conventional brake booster. Accordingly, when the flange 84 and the valve seat member 82 are relatively separated from each other, the repulsive force by the magnets 90 and 92 does not substantially act, and the springs 102 and 106 are applied to the flange 84 and the valve seat member 82. Due to the large elastic force, a large force acts in the sitting direction. That is, compared with the conventional brake booster, the valve closing speed is high, and the time from when the brake operation member is held until the valve is closed is shortened. Therefore, according to this brake booster, the fall of the reaction force with respect to the brake operation member mentioned above is suppressed.

  However, since the set load of the springs 102 and 106 is increased, considering only the springs 102 and 106, a large force is applied when starting to depress the brake operation or depressing the held brake operation member again. It becomes necessary. On the other hand, the brake booster 10 is configured such that the flanges 84 and the valve seat member are shown in FIG. 5 by magnets 90 and 92 provided on the flange 84 and the valve seat member 82 of the reaction rod 60. A repulsive force that increases as the distance from the terminal 82 increases. More specifically, the repulsive force of the magnets 90 and 92 increases as the approaching force increases. Further, the repulsive force is smaller than the approaching force generated by the springs 102 and 106.

  In other words, as indicated by the solid line in FIG. 5, the brake booster 10 is configured to start the brake operation or to hold the brake that has been held even though the valve closing speed is set high as described above. The operating force required to depress the operating member again is set to the same magnitude as that of a conventional brake booster.

  10: Brake booster 12: Operating rod [input rod] 14: Push rod 20: Negative pressure chamber 22: Transformer chamber 24: Housing 26: Valve portion 28: Diaphragm 40: Power piston 50: Reaction disk 52: First communication hole 54 : Second communication hole 60: reaction rod [input rod] 70: control valve 76: stepped portion 82: valve seat member [valve seat and valve mechanism] 84: flange [valve element and valve mechanism] 90: magnet 92: magnet 102 : Compression coil spring [return spring] 106: Compression coil spring [return spring]

Claims (1)

A brake booster that uses the differential pressure between a negative pressure chamber into which negative pressure is introduced and a variable pressure chamber into which air can be introduced, to assist the driver in operating the brake operation,
An input rod that can be moved forward and backward in accordance with the driver's brake operation;
A return spring that urges the input rod in a direction to retract,
A part of the input rod functions as a valve body, and by allowing the input rod to move away from the valve seat and permit introduction of the atmosphere into the variable pressure chamber, the reverse rod is seated on the valve seat and retracted to the variable pressure chamber. And a valve mechanism that prohibits the introduction of air into the
The valve mechanism is
A brake booster, comprising a pair of magnets that are provided on each of the part of the input rod and the valve seat and generate a repulsive force between the part of the input rod and the valve seat.

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