WO2013012033A1

WO2013012033A1 - Negative pressure servo device

Info

Publication number: WO2013012033A1
Application number: PCT/JP2012/068320
Authority: WO
Inventors: 陽一寺崎; 智康酒井; 雅樹仲川
Original assignee: 株式会社アドヴィックス
Priority date: 2011-07-21
Filing date: 2012-07-19
Publication date: 2013-01-24
Also published as: JP2013023083A; CN103702877B; JP5565590B2; CN103702877A

Abstract

A holding means for holding a slide valve (60) at a predetermined front position includes a locking member (64) assembled to a power piston (30) so as to be capable of moving linearly in the radial direction, and a gutter spring (65) that impels the locking member (64) inward in the radial direction. The locking member (64) is provided with a hook (64a) that can be engaged to and disengaged from a hook (60b) provided to the slide valve (60) and forms the holding means with the gutter spring (65) or the like. When a plunger (41) advances with respect to the power piston (30) to an extent greater than a predetermined value, a pressed slope surface (64c) of the locking member (64) is pressed outward in the radial direction by a pressing slope surface (41d) of the plunger (41), and the hook (64a) of the locking member (64) is detached from the hook (60b) of the slide valve (60). A relief part (30m) is provided in the power piston (30), corresponding to the key member (63). Thereby, it is possible to solve the problems associated with defects due to bending deformation of the key member without causing new problems (increase in costs, increase in axial dimensions or the like).

Description

Negative pressure booster

The present invention relates to a negative pressure booster that is employed in a vehicle brake device, and more particularly to a negative pressure booster that can make up for a lack of brake pedal depression force during emergency braking.

One example of such a negative pressure booster is described in Patent Document 1 below. This is configured so that its input-output characteristics can be switched between normal brake characteristics and emergency brake characteristics. During emergency braking, the input-output characteristics of the negative pressure booster are changed from normal brake characteristics to emergency brake characteristics. By switching to the brake characteristic, the same result as when the driver depresses the brake pedal strongly is obtained.

JP 2005-138612 A

The negative pressure booster described in Patent Document 1 described above includes a movable partition that divides the inside of the housing into a constant pressure chamber and a variable pressure chamber, a power piston coupled to the movable partition, and the power piston. An input member that is installed to be able to move forward and backward with respect to the power piston and receives an operating force from the outside, an output member that outputs the propulsive force of the power piston to the outside, and the power between the power piston and the input member A slide valve that is coaxially assembled to the piston and capable of moving back and forth, and a holding means that holds the slide valve in a predetermined position forward when the amount of advance of the input member relative to the power piston is a predetermined value or less, When the advance amount of the input member relative to the power piston is larger than a predetermined value, the movable means moves the slide valve to the rear position by a predetermined amount. A return means for returning the slide valve to the predetermined position when the power piston and the slide valve return to the predetermined position with respect to the housing; and an atmospheric valve seat provided on the input member; Controls communication / interruption between the variable pressure chamber and the constant pressure chamber by an atmospheric control valve unit that controls communication / interruption between the variable pressure chamber and the atmosphere and a negative pressure valve seat provided on the power piston and / or the slide valve. A control valve having a negative pressure control valve portion that is assembled in the power piston, and the holding means is assembled to the power piston so as to be linearly movable in the radial direction. A locking member and a biasing member that biases the locking member toward the radially inward direction, and the locking member can be engaged with and disengaged from a hook provided on the slide valve. Hook constituting the holding means is provided by a wood. Note that the rear means the brake pedal side or the vehicle rear side with respect to the negative pressure booster, and the front means the brake master cylinder side or the vehicle front side with respect to the negative pressure booster.

Further, in the negative pressure type booster described in Patent Document 1 described above, the power piston and the slide valve are in a predetermined position with respect to the housing (the brake operation is completed and the brake pedal is returned to the initial position). A key member that comes into contact with the housing at both ends projecting radially outward from the power piston and comes into contact with the power piston and the slide valve at an intermediate portion between the both ends when returning to the return position) Is adopted. The key member is formed of a plate thickness and material that does not deform under normal use. Therefore, when the power piston and the slide valve return to a predetermined position with respect to the housing, a hook provided on the slide valve is provided. Each of the hooks provided on the locking member (which is assembled to the power piston so as to be linearly movable in the radial direction and moves integrally with the power piston in the axial direction of the power piston) is also predetermined. It is set so that it returns to the position, engages with each other, and returns to the initial state (from the emergency brake characteristic to the normal brake characteristic).

By the way, when the brake pedal is strongly pulled backward from the returned position (initial position) (this is not a normal use, the anti-theft device that prevents the brake pedal from being depressed) In the case of abnormal use such that the rear end is strongly pulled backward, the intermediate portion of the key member may be pulled backward with respect to both end portions to bend and deform. In this case, due to the curved deformation of the key member, a predetermined front-back difference occurs at a predetermined position (return position) with respect to the housing of the power piston and the slide valve, so that the hook provided on the slide valve and the locking member are provided. There is a risk that the hook will not be engaged and will not return to the initial state (in this case, the emergency braking characteristic will not return to the normal braking characteristic and the feeling will deteriorate during normal braking). In addition, although the above-mentioned subject (problem resulting from the curved deformation in the key member) can be solved by changing the thickness and material of the key member to one that is difficult to bend and deformed, in this case, Cost increases. Further, the above-described problem is that the dimensions of each part are such that the hook provided on the slide valve and the hook provided on the locking member are engaged even if a predetermined front-back difference occurs at a predetermined position with respect to the power piston and the slide valve housing. However, in this case, the axial dimension of the negative pressure booster as a whole increases.

The present invention was made to solve the above-described problems without causing new problems (cost increase, axial dimension increase, etc.), and in the negative pressure type booster of the above-described type,
When the power piston and the slide valve return to a predetermined position with respect to the housing, the power piston contacts the housing at both ends projecting radially outward from the power piston and the power at the intermediate portion between both ends. A key member that contacts the piston and the slide valve is adopted,
When the intermediate portion of the key member is curved and deformed backward with respect to both end portions, a relief portion is provided in the power piston or the key member for securing a required amount of return of the slide valve with respect to the power piston. And
Even when the intermediate portion of the key member is curved and deformed backward with respect to both end portions, the slide valve provided in the slide valve that is in contact with the inner diameter of the intermediate portion of the key member and is restricted from moving backward. The hook is set to engage with the hook of the locking member assembled to the power piston, which is in contact with the outer portion of the intermediate diameter of the key member and is restricted from moving backward. There are features.

In carrying out the present invention, the relief portion is a recess formed in the power piston or the key member along the radial direction of the power piston, and a radially outward portion in the recess is compared with a radially inward portion. It is also possible to form it so as to become deeper in order. The relief portion is a recess formed in the power piston or the key member along the radial direction of the power piston, and the recess is formed to have the same depth over the entire length in the radial direction. It is also possible.

In the above-described negative pressure type booster of the present invention, when the above-described relief portion is provided in the power piston or the key member, and the intermediate portion of the key member is curved and deformed backward with respect to both end portions. Also, the hook provided on the slide valve that is in contact with the inner diameter of the intermediate portion of the key member and is restricted from moving backward, and the outer portion of the key member is in contact with the outer diameter of the intermediate portion. It is set so that the hook of the locking member assembled to the power piston that is restricted from moving is engaged. For this reason, even if the intermediate portion of the key member may bend and deform backward with respect to both end portions, when the power piston and the slide valve return to predetermined positions with respect to the housing, the hook provided on the slide valve The hook provided on the locking member is engaged to return to the initial state.

Further, in the negative pressure type booster of the present invention described above, since the above-described relief portion can be implemented by providing the power piston or the key member, the thickness and material of the key member can be changed. There is no increase in cost and no increase in the axial dimension (size increase) of the negative pressure booster as a whole.

FIG. 1 is a sectional view showing an embodiment of a negative pressure booster according to the present invention. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a sectional view of the power piston shown in FIG. 4 is a front view of the single slide valve shown in FIG. FIG. 5 is a side view of the single slide valve shown in FIG. 6 is a plan view of the single slide valve shown in FIG. FIG. 7 is a rear view of the slide valve alone shown in FIG. FIG. 8 schematically shows a return state when the key member is bent and deformed. FIG. 8A is a view when the escape portion is provided in the power piston, and FIG. 8B is the escape state in the power piston. It is a figure in case a part is not provided. FIG. 9 is a cross-sectional view corresponding to FIG. 2 of a modified embodiment of the present invention. FIG. 10 is a cross-sectional view corresponding to FIG. 3 of another modified embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 8 show an embodiment of a negative pressure booster according to the present invention. This negative pressure booster includes a movable partition wall 20 and a power piston 30 assembled to a housing 10, and power. An input member 40, an output member 50, a slide valve 60, a control valve 70, and the like that are assembled to the piston 30 are provided.

As shown in FIG. 1, the housing 10 includes a front shell 11 and a rear shell 12, and a negative pressure source (for example, an intake manifold of an engine (not shown)) is internally passed through a negative pressure introduction pipe 13 by a movable partition wall 20. Are constantly divided into a constant pressure chamber R1 and a variable pressure chamber R2 which communicates with and shuts off the constant pressure chamber R1 and the atmosphere. The housing 10 has a stationary member, that is, a screw member provided at a rear end portion of a plurality of tie rods 14 (one is shown in FIG. 1) penetrating the housing 10 and the movable partition wall 20 in an airtight manner. It is configured to be fixed to a vehicle body (not shown). Note that a brake master cylinder 100 is assembled to a thread portion provided at the front end portion of the tie rod 14.

The movable partition wall 20 includes a metal plate 21 and a rubber diaphragm 22, and is installed so as to be movable in the front-rear direction with respect to the housing 10. The diaphragm 22 is airtightly sandwiched between the folded portion provided on the outer peripheral edge of the rear shell 12 and the front shell 11 at a bead portion formed on the outer peripheral edge thereof. The diaphragm 22 is airtightly fixed together with the plate 21 in a groove provided on the outer periphery of the front flange portion of the power piston 30 at a bead portion formed on the inner peripheral edge thereof.

The brake master cylinder 100 shown in FIG. 1 has a rear end portion 101a of the cylinder body 101 penetrating through a central cylindrical portion formed in the front shell 11 and airtightly entering the constant pressure chamber R1. The rear surface of the flange portion 101 b formed in contact with the front surface of the front shell 11. Further, the piston 102 of the brake master cylinder 100 protrudes rearward from the cylinder body 101 and enters the constant pressure chamber R1, and is configured to be pushed forward by the tip of the output member 50.

The power piston 30 is a hollow piston coupled to the movable partition wall 20 and is assembled to the rear shell 12 of the housing 10 so as to be airtight and movable in the front-rear direction at a portion formed in a cylindrical shape. A spring 31 interposed between the housing 10 and the front shell 11 is urged rearward. 2 and 3, the power piston 30 has a reaction force chamber hole 30a and a contact member housing hole having a smaller diameter than the reaction force chamber hole 30a from the front end surface toward the rear end surface. 30b, a plunger housing hole 30c, a plunger / valve housing hole 30d having a diameter larger than that of the plunger housing hole 30c, a control valve housing hole 30e, a filter housing hole 30f and the like are sequentially provided, and are continuous with the reaction force chamber hole 30a. An annular groove 30g is provided concentrically with the contact member accommodation hole 30b. 1, 2, and 3, a cross section along the longitudinal direction of the key member 63 assembled to the power piston 30 in the lower half from the axial center of the power piston 30 (the dashed line in FIGS. 1 and 2). The cross section orthogonal to the longitudinal direction of the key member 63 is described in the upper half of the axial center of the power piston 30.

The power piston 30 is provided with a locking member mounting hole 30h in the radial direction corresponding to the plunger housing hole 30c, and a key member insertion hole 30i in the radial direction corresponding to the plunger / valve housing hole 30d. It has been. Further, the power piston 30 is provided with a pair of communication holes 30j (only one of which is shown in FIG. 2) capable of communicating the constant pressure chamber R1 and the control valve housing hole 30e, and each of these communication holes 30j. An arc-shaped negative pressure valve seat 30k on which the negative pressure valve portion 70a of the control valve 70 can be seated is formed at the rear end portion.

The input member 40 is a member that can be moved forward and backward with respect to the power piston 30 and receives an operating force from the outside. The input member 40 is received in the control valve storage hole 30e from the contact member storage hole 30b of the power piston 30 and is connected to the power piston 30. The plunger 41 is movable in the axial direction (front-rear direction) with respect to 30, and is connected to the plunger 41 in a joint shape by a spherical tip 42a and to the brake pedal 110 (see FIG. 1) at the rear end 42b. The input rod 42 is provided.

As shown in FIG. 2, the plunger 41 is opposed to the power piston 30 via a contact member 81 that is assembled at the tip thereof to the contact member housing hole 30b of the power piston 30 so as to be movable in the axial direction. An annular atmospheric valve seat 41 a that can be engaged with the reaction force member 82 accommodated in the force chamber hole 30 a and is detachably seated on the atmospheric valve portion 70 b of the control valve 70 is formed. The reaction force member 82 is a reaction rubber disk, and comes into contact with the reaction force receiving surface of the power piston 30 while being accommodated in the cylindrical portion 51 a of the rear member 51 of the output member 50, and the front surface of the contact member 81. Can be contacted.

The output member 50 is integrated with a reaction member 82 and a rear member 51 assembled in the reaction force chamber hole 30a and the annular groove 30g of the power piston 30 so as to be movable in the axial direction, and a front end portion of the rear member 51. The front end of the output rod 52 abuts against the engaging portion of the piston 102 in the brake master cylinder 100 so as to be slidable.

As shown in FIGS. 2 and 4 to 7, the slide valve 60 is coaxially movable back and forth between the power piston 30 and the input member 40 via the airtight seal ring 61 to the power piston 30 (in the axial direction). And is urged rearward by a spring 62 interposed between the power piston 30 and the slide valve 60, and seated on the second negative pressure valve portion 70c of the control valve 70 at the rear end thereof. A possible second negative pressure valve seat 60a is formed. The slide valve 60 is configured such that its axial movement position is defined by a key member 63, a locking member 64, a garter spring 65, and the like assembled to the power piston 30.

The slide valve 60 has a pair of hooks 60b and a pair of pushing slopes 60c on the outer periphery of the front end portion, and has a seal mounting groove 60d and a locking surface 60e (see FIGS. 5 and 6) in the middle. is doing. Each hook 60b can be engaged with and disengaged from an arcuate hook 64a formed at the rear inner end of the locking member 64, and each pushing slope 60c is a circle formed at the rear inner end of the locking member 64. It is possible to disengage from the arcuate passive slope 64b. Further, the locking surface 60e can be engaged and disengaged from the front surface of the key member 63. A pair of slits 60f (see FIGS. 4 and 5) is provided from the front end of the slide valve 60 to the front of the seal mounting groove 60d.

The key member 63 defines the initial positions (return positions) of the power piston 30, the plunger 41, the slide valve 60, etc. with respect to the housing 10, and also defines the axial movement of the plunger 41 and the slide valve 60 with respect to the power piston 30. The key member insertion hole 30i in the radial direction formed in the power piston 30 is inserted. The thickness dimension of the key member 63 in the front-rear direction is smaller than the dimension in the front-rear direction of the key member insertion hole 30 i, and the key member 63 can move in the front-rear direction by a predetermined amount with respect to the power piston 30.

The key member 63 can be brought into contact with the rear shell 12 at the rear end surfaces of both end portions projecting radially outward from the power piston 30, and the rearward movement limit position of the power piston 30 relative to the housing 10 is shown in FIG. As shown, the front wall of the key member insertion hole 30 i is in contact with the front end surface of the key member 63, and the rear end surfaces of both ends of the key member 63 are in contact with the rear shell 12. Further, the key member 63 can be brought into contact with the front and rear end surfaces 41b and 41c of the annular groove formed in the central portion of the plunger 41 at an intermediate portion between the both end portions, and the rear side of the plunger 41 with respect to the power piston 30. The movement limit position is a position where the front end surface 41b of the annular groove is in contact with the front end surface of the key member 63 and the rear end surface of the key member 63 is in contact with the rear wall of the key member insertion hole 30i. Further, the forward movement limit position of the plunger 41 with respect to the power piston 30 is such that the rear end surface 41c of the annular groove abuts the rear end surface of the key member 63 via the O-ring 43 and the front end surface of the key member 63 is inserted through the key member. This is the position in contact with the front wall of the hole 30i.

The key member 63 has a locking surface 60e (FIGS. 5, 6 and 5) formed in the intermediate portion of the slide valve 60 on the front surface of the intermediate portion (portion outside the portion contacting the plunger 41). 8) and the slide valve 60 is moved to the rear position with respect to the power piston 30, and the power piston 30 and the slide valve 60 are shown in FIG. When returning to the position, the backward movement of the slide valve 60 is restricted before the backward movement of the power piston 30 is restricted, and the slide valve 60 is resisted against the urging force of the spring 62 with respect to the power piston 30. To return to a predetermined position in front.

As shown in FIGS. 1 and 2, the locking member 64 is linearly movable in the radial direction from the outer periphery of the power piston 30 to the radial locking member mounting hole 30 h formed in the power piston 30. It is assembled, can project toward the outer periphery of the power piston 30, and is biased radially inward by a garter spring 65 attached to the outer periphery of the power piston 30. In this embodiment, although not shown in the drawing, a pair of two locking members 64 are used, and they are opposed to each other in the radial direction.

In the locking member 64, as shown in FIG. 2, a hook 64a that can be engaged with and detached from the hook 60b in the slide valve 60, and a passive slope 64b that can be engaged with and detached from the pushing slope 60c in the slide valve 60. An annular push slope 41d formed on the plunger 41 and a passive slope 64c that can be engaged and disengaged are formed at the inner end, and a stopper 30h1 formed in the locking member mounting hole 30h of the power piston 30 (the step in FIG. 3). A step portion (not shown) that can come into contact with the intermediate portion is formed in the intermediate portion, and a mounting groove 64e of the garter spring 65 is formed in the outer end portion.

For this reason, when the advance amount of the plunger 41 relative to the power piston 30 in the input member 40 at the position shown in FIG. 2 is equal to or less than a predetermined value, the pushing slope 41d formed on the plunger 41 is the passive member of the locking member 64. The hook 60b of the slide valve 60 and the hook 64a of the locking member 64 can be engaged with each other without being engaged with the inclined surface 64c, and as shown in FIG. Retained. Accordingly, the hook 64a of the locking member 64, the hook 60b of the slide valve 60, the garter spring 65, and the like function as holding means for holding the slide valve 60 at a predetermined position in front.

When the advance amount of the plunger 41 with respect to the power piston 30 in the input member 40 is larger than a predetermined value, the pushing slope 41d formed on the plunger 41 engages with the passive slope 64c of the locking member 64, The stop member 64 is pushed radially outward against the biasing force of the garter spring 65. For this reason, the hook 60b of the slide valve 60 is released from the engagement with the hook 64a of the locking member 64, and the slide valve 60 is moved to a rear position by a predetermined amount by the spring 62. A second negative pressure valve seat 60 a formed at the rear end is seated on the second negative pressure valve portion 70 c of the control valve 70. Therefore, the pushing slope 41d of the plunger 41, the passive slope 64c of the locking member 64, the spring 62, and the like function as movable means for moving the slide valve 60 to the rear position by a predetermined amount.

Further, in a state where the slide valve 60 is moved to the rear position with respect to the power piston 30, the power piston 30 and the slide valve 60 are moved to the predetermined position shown in FIG. When returning, since the slide valve 60 returns to the predetermined position and stops immediately before the power piston 30 returns to the predetermined position, the passive inclined surface 64b of the locking member 64 engages with the pushing inclined surface 60c of the slide valve 60. Thus, the locking member 64 is temporarily pushed radially outward against the urging force of the garter spring 65.

For this reason, when the power piston 30 returns to the predetermined position, the locking member 64 is pushed inward in the radial direction by the biasing force of the garter spring 65, and the hook 64a of the locking member 64 is re-engaged with the hook 60b of the slide valve 60. It will be in the state which can be engaged. Therefore, the key member 63, the pushing slope 60c of the slide valve 60, the passive slope 64b of the locking member 64, the garter spring 65, and the like function as return means for returning the slide valve 60 to a predetermined position in the front.

The control valve 70 is hermetically sealed with an annular movable portion 70A having the negative pressure valve portion 70a, the atmospheric valve portion 70b and the second negative pressure valve portion 70c, and a step portion formed in the control valve accommodation hole 30e of the power piston 30. It is comprised by the cyclic | annular fixing | fixed part 70B by which it fitted and fixed, and the cylindrical bellows part 70D which connects the cyclic | annular movable part 70A and the cyclic | annular fixed part 70B. The annular movable portion 70A is urged forward by a spring 71 interposed between the input rods 42 and is movable in the front-rear direction. The annular fixing portion 70 </ b> B is urged forward by a spring 72 interposed between the input rods 42 and is fixed to the power piston 30.

The negative pressure valve portion 70a can be seated on and separated from a pair of arc-shaped negative pressure valve seats 30k formed on the power piston 30, and the constant pressure chamber R1 and the variable pressure chamber R2 communicate with each other by being seated on the arc-shaped negative pressure valve seat 30k. The constant pressure chamber R1 and the variable pressure chamber R2 are made to communicate with each other by being separated from the arcuate negative pressure valve seat 30k. The atmospheric valve portion 70b can be seated / separated on an annular atmospheric valve seat 41a formed on the plunger 41. The seating on the annular atmospheric valve seat 41a blocks the communication between the variable pressure chamber R2 and the atmosphere. The variable pressure chamber R2 and the atmosphere are communicated by being separated from the atmosphere valve seat 41a. The second negative pressure valve portion 70c can be seated and separated from a second negative pressure valve seat 60a formed on the slide valve 60, and the constant pressure chamber R1 and the variable pressure chamber R2 can be seated on the second negative pressure valve seat 60a. And the constant pressure chamber R1 and the variable pressure chamber R2 are communicated with each other by separating from the second negative pressure valve seat 60a.

The

filters

91 and 92 are mounted between the input rods 42 in the filter housing hole 30f of the power piston 30, and the

filters

91 and 92 are provided with a boot 93 that protects the sliding portion of the power piston 30 from the outer periphery. Air can flow in through the formed vent 93a. The boot 93 is fitted and fixed to the rear end cylinder portion of the rear shell 12 in the housing 10 at the front end portion, and is fitted and fixed to the outer periphery of the intermediate portion of the input rod 42 at the rear end portion.

Incidentally, in this embodiment, the escape portion 30m is provided in the power piston 30 corresponding to the key member 63 that defines the initial position (return position). The relief portion 30m is a concave portion (inclined portion) formed in the power piston 30 along the radial direction of the power piston 30, and a radially outward portion (a lower portion in FIG. 2) is a radially inward portion ( It is formed so as to be sequentially deeper than the upper part in FIG. 2 (formed in a shape inclined forward toward the outside of the diameter). For this reason, when the intermediate part of the key member 63 is curved and deformed backward with respect to both end parts (see FIG. 8A), the return amount of the slide valve 60 with respect to the power piston 30 (power piston 30) by the relief part 30m. The amount of return of the power piston 30 relative to the housing 10 as compared with the case where the required amount is secured and the escape portion 30m is not provided (see FIG. 8B). (Movement backward) is increased.

Therefore, in this embodiment, even when the intermediate portion of the key member 63 is bent backward with respect to both end portions (see FIG. 8A), the intermediate portion of the key member 63 is rearward with respect to both end portions. When the brake pedal 110 is returned to the initial position (return position) in FIG. 1 and the power piston 30 is returned to the predetermined position (initial position), as in the case where it does not bend and deform (see FIG. 2), the key member 63 Power of the slide valve 60 which is in contact with the inner diameter of the intermediate portion of the slide valve 60, and the movement of the key member 63, which is restricted from moving backward. The hook 64a of the locking member 64 assembled to the piston 30 is engaged, and an axial clearance is formed between the

hooks

60b and 64a. The axial gap formed between the

hooks

60b and 64a in the case shown in FIG. 8A is S1, and the axial direction formed between the

hooks

60b and 64a in the case shown in FIG. Although smaller than the gap S2, it is possible to set the axial gap S1 so as to be substantially zero.

In the negative pressure booster of this embodiment configured as described above, as shown in FIG. 2, during normal braking when the intermediate portion of the key member 63 is not curved and deformed backward with respect to both ends. Since the relative movement amount of the input member 40 and the power piston 30 (the advance amount of the input member 40 with respect to the power piston 30) is equal to or less than a predetermined value, the pushing slope 41d of the plunger 41 becomes the passive slope 64c of the locking member 64. Without being engaged, the slide valve 60 is held at a predetermined position in front (a position where the hook 60b of the slide valve 60 is engaged with the hook 64a of the locking member 64 shown in FIG. 2). Therefore, at this time, the slide valve 60 hardly moves with respect to the power piston 30, and a generally known normal brake operation is obtained.

On the other hand, at the time of emergency braking in which the driver hurries and depresses the brake pedal 110, the relative movement amount of the input member 40 and the power piston 30 (the advance amount of the input member 40 with respect to the power piston 30) becomes larger than a predetermined value. At this time, the pushing slope 41d of the plunger 41 is engaged with the passive slope 64c of the locking member 64, and the locking member 64 is pushed radially outward against the biasing force of the garter spring 65. For this reason, the hook 60 b of the slide valve 60 is disengaged from the hook 64 a of the locking member 64, and the slide valve 60 is moved to a rear position by a predetermined amount by the spring 62.

When the slide valve 60 moves rearward, the second negative pressure valve seat 60a formed at the rear end of the slide valve 60 is seated on the second negative pressure valve portion 70c of the control valve 70, and the constant pressure chamber R1 and the variable pressure chamber Block communication with R2. At this time, the plunger 41 is moving forward integrally with the input rod 42, and the slide valve 60 pushes back the movable portion 70A of the control valve 70, so that an annular shape formed at the rear end of the plunger 41 is reached. The atmospheric valve seat 41a and the atmospheric valve portion 70b of the control valve 70 are rapidly separated, and the variable pressure chamber R2 communicates with the atmosphere. As a result, compared with the normal braking operation, the communication between the constant pressure chamber R1 and the variable pressure chamber R2 is rapidly cut off and the communication between the variable pressure chamber R2 and the atmosphere is performed rapidly, and the output in the jumping state can be made larger than the normal state. Thus, it becomes possible to obtain a larger propulsive force (output) than during normal braking.

Further, when the emergency brake operation described above is completed and the brake pedal 110 is returned, the plunger 41 moves rearward while the front end surface 41b of the annular groove is in contact with the key member 63. When the key member 63 comes into contact with the rear shell 12, the key member 63 comes into contact with the locking surface 60 e of the slide valve 60 and restricts the rearward movement of the slide valve 60 that has moved backward together with the power piston 30. Thereafter, since the power piston 30 is further retracted, the passive inclined surface 64b of the locking member 64 that is integrally retracted with the power piston 30 is engaged with the pushing inclined surface 60c of the slide valve 60, and the locking member 64 is moved to the garter. The spring 65 is temporarily pushed outward in the radial direction against the urging force of the spring 65.

Therefore, when the power piston 30 returns to a predetermined position (the initial position in FIG. 2), the locking member 64 is pushed inward in the radial direction by the biasing force of the garter spring 65, and the hook 64a of the locking member 64 slides. It will be in the state (initial state) which re-engages with the hook 60b of the valve | bulb 60. FIG. Therefore, the next emergency braking operation is prepared.

By the way, in the negative pressure type booster of the above-described embodiment, the above-described relief portion 30m is provided in the power piston 30, and as shown in FIG. Even when the power piston 30 returns to a predetermined position (initial position) even when it is curved and deformed backward with respect to both end portions, the rearward movement is restricted by coming into contact with the inner diameter portion of the intermediate portion of the key member 63. The hook 60b provided on the slide valve 60 and the hook 64a of the locking member 64 assembled to the power piston 30 which is in contact with the outer portion of the intermediate diameter of the key member 63 and is restricted from moving backward. It is set to match. For this reason, even if the intermediate portion of the key member 63 may bend and deform backward with respect to both end portions, when the power piston 30 and the slide valve 60 return to the predetermined position (return position) with respect to the housing 10, respectively. 8A, the hook 60b provided on the slide valve 60 and the hook 64a provided on the locking member 64 are engaged, and the slide valve 60 is in an initial state with respect to the power piston 30. Return to.

Further, in the negative pressure type booster of the above-described embodiment, the above-described relief portion 30m can be provided in the power piston 30, so that the cost increases as the thickness and material of the key member 63 are changed. In addition, there is no increase in the axial dimension (size increase) of the negative pressure booster as a whole. In the negative pressure booster of the above-described embodiment, various functions and effects described in Japanese Patent Application Laid-Open No. 2005-138612 can be obtained.

In addition, in the negative pressure type booster of the above-described embodiment, when the above-described relief portion 30m is not provided in the power piston 30, as shown in FIG. When the portion is curved and deformed backward with respect to both end portions, the power piston 30 that is in contact with the outer diameter portion of the intermediate portion of the key member 63 and is restricted from moving rearward does not move rearward sufficiently (does not return). ). For this reason, a predetermined front-back difference occurs at a predetermined position (respective return positions) of the power piston 30 and the slide valve 60 with respect to the housing 10, and a hook 60b provided on the slide valve 60 and a hook 64a provided on the locking member 64 are provided. As a result, the slide valve 60 does not return to the initial state with respect to the power piston 30. In this case, the emergency braking characteristic does not return to the normal braking characteristic, and the feeling may deteriorate during normal braking.

In the above-described embodiment, the above-described relief portion 30m is provided in the power piston 30. However, as shown in FIG. 9, the relief portion 63a corresponding to the above-described relief portion 30m is provided in the key member 63. Can also be implemented. In the above-described embodiment, the above-described relief portion 30m is a concave portion (inclined portion) formed in the power piston 30 along the radial direction of the power piston 30, and a radially outward portion (in FIG. 2) The lower part) is formed so as to be sequentially deeper than the radially inner part (upper part in FIG. 2), but as shown in FIG. It is also possible to form a recess formed in the power piston 30 along the same length, and this recess may be formed to have the same depth over the entire length in the radial direction.

As in the embodiment shown in FIG. 9, in the relief portion 63 a provided in the key member 63, the concave portion (relief portion 63 a is formed so that the radially outer portion is sequentially deeper than the radially inner portion. ) In the relief portion provided in the key member, the rigidity of the key member is greater than that in the case where the recess is formed so as to have the same depth over the entire length in the radial direction. Can be secured sufficiently. Further, as in the embodiment shown in FIG. 10, in the relief portion 30 m provided in the power piston 30, when the recess is formed so as to have the same depth over the entire length in the radial direction, As compared with the case where the concave portion is formed so that the outer portion is sequentially deeper than the radially inner portion, the escape portion can be easily manufactured.

In the above-described embodiment, the negative pressure valve seat 30k is provided in the power piston 30 and the negative pressure valve seat 60a is provided in the slide valve 60, and the present invention is implemented. However, the negative pressure when the slide valve 60 is in the forward position is provided. When the position of the pressure valve seat 60a is set to be the position of the negative pressure valve seat 30k described above, the power piston 30 can be implemented without providing the negative pressure valve seat 30k.

In the above-described embodiment, the present invention is applied to a single negative pressure booster. However, the present invention can be similarly applied to a tandem or triple negative pressure booster. Of course, the present invention can be implemented with appropriate modifications within the scope of the claims.

Claims

A movable partition that divides the inside of the housing into a constant pressure chamber and a variable pressure chamber, a power piston coupled to the movable partition, and a power piston that is installed in the power piston so as to be able to move forward and backward, and to operate from the outside An input member that receives the power piston, an output member that outputs the propulsive force of the power piston to the outside, and a slide valve that is mounted coaxially and forward and backward between the power piston and the input member, When the advance amount of the input member relative to the power piston is less than or equal to a predetermined value, the holding means for holding the slide valve in a predetermined position forward, and when the advance amount of the input member relative to the power piston is greater than a predetermined value Movable means for moving the slide valve to a rear position by a predetermined amount, the power piston and the slide valve include the housing. Return means for returning the slide valve to the predetermined position in front when the slide valve returns to a predetermined position, and communication between the variable pressure chamber and the atmosphere by an atmospheric valve seat provided on the input member. A negative pressure control valve portion for controlling communication / blocking between the variable pressure chamber and the constant pressure chamber by an atmospheric control valve portion for controlling the shutoff and a negative pressure valve seat provided on the power piston and / or the slide valve; A control valve assembled in the power piston, the holding means being assembled to the power piston so as to be linearly movable in the radial direction, and a diameter of the locking member A biasing member that biases inward is provided, and the locking member includes a hook that is detachable from a hook provided on the slide valve and that constitutes the holding means by the biasing member. Provided In the vacuum booster,
When the power piston and the slide valve return to a predetermined position with respect to the housing, the power piston contacts the housing at both ends projecting radially outward from the power piston and the power at the intermediate portion between both ends. A key member that contacts the piston and the slide valve is adopted,
When the intermediate portion of the key member is curved and deformed backward with respect to both end portions, a relief portion is provided in the power piston or the key member for securing a required amount of return of the slide valve with respect to the power piston. And
Even when the intermediate portion of the key member is curved and deformed backward with respect to both end portions, the slide valve provided in the slide valve that is in contact with the inner diameter of the intermediate portion of the key member and is restricted from moving backward. The hook is set to engage with the hook of the locking member assembled to the power piston, which is in contact with the outer part of the intermediate diameter of the key member and is restricted from moving backward. Characteristic negative pressure booster.
2. The negative pressure type booster according to claim 1, wherein the relief portion is a recess formed in the power piston or the key member along a radial direction of the power piston. A negative pressure type booster characterized by being formed so as to become deeper in comparison with the radially inner portion.
2. The negative pressure type booster according to claim 1, wherein the relief portion is a recess formed in the power piston or the key member along a radial direction of the power piston, and the recess extends over the entire length in the radial direction. The negative pressure booster is characterized by being formed to have the same depth.