JPH0753003Y2 - Negative pressure booster for shifting - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Field of Industrial Use The present invention is mainly for boosting a transmission of a large automobile such as a truck by using the negative pressure of a negative pressure source to boost the transmission. A negative pressure booster for speed change.

(2) Conventional technology Such a negative pressure booster for speed change is disclosed in, for example, Japanese Patent Publication No. 54-35278.
It is already known as disclosed in the publication.

(3) Problems to be Solved by the Invention In the negative pressure booster for speed change disclosed in the above publication, the booster piston is boosted by negative pressure of the negative pressure source according to the movement of the input member to shift the transmission. However, a reaction force is not generated in the input member during the shift, and therefore the operator cannot sense the magnitude of the output of the booster piston, so a good shift feeling is obtained. It has the drawback of not having it.

The present invention has been made in view of such circumstances, and during the shift of the transmission, the reaction force corresponding to the output of the booster piston acts on the input rod to obtain a good shift feeling.
Moreover, it is an object of the present invention to provide a speed-changing negative pressure booster in which the input rod is prevented from rattling due to manufacturing error of each part.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above-mentioned object, the negative pressure booster for speed change of the present invention includes a negative pressure source, a booster shell, and a reciprocating motion in the booster shell. Is housed in the first and second
A booster piston partitioning into the working chamber; first and second valve cylinders projecting from both ends of the booster piston and penetrating both end walls of the booster shell; and booster pistons housed in the first and second valve cylinders, respectively. Can move a fixed stroke defined by the inward movement limit on the side and the outward movement limit on the opposite side, and is opposed to the first and second reaction force chambers on the booster piston side in the first and second valve cylinders, respectively. First and second reaction force pistons that are divided into first and second atmosphere chambers on the side; first and second biasing the first and second reaction force pistons toward the inward movement limit, respectively. A return spring;
An input member that slidably penetrates the first and second reaction force pistons and that has a pair of contact step portions that can contact the inner ends of the reaction force pistons and that is connected to the speed change lever; Two
When the reaction force pistons are respectively disposed in the valve cylinders and are located in the inward movement limit, the corresponding working chambers and reaction force chambers are made incommunicable with the negative pressure source and communicated with the respective atmospheric chambers. When the reaction force piston is moved toward the outward movement limit by the contact step portion of the input member, the first and first communication chambers and the reaction force chamber are made incommunicable with the atmosphere chambers and communicate with the negative pressure source. 2 control valves;
An output member that is driven by the booster piston to give a shift operation to the transmission, and restricts a distance between a pair of contact step portions of the input member and an inward movement limit of the first and second reaction force pistons. It is characterized in that the distance is set to be larger than the distance between the pair of restriction portions provided on the first and second valve cylinders, respectively.

(2) Operation In the above structure, if the first reaction force piston is moved toward the outer limit of its movement by the speed change lever via the input member, the first operation chamber and the first operation chamber and the first operation chamber are switched by the switching operation of the first control valve. Since the first reaction force chamber becomes in communication with the first atmosphere chamber and communicates with the negative pressure source, a pressure difference is generated between the first and second working chambers and between the first atmosphere chamber and the first reaction force chamber. Then, according to the atmospheric pressure difference between the first and second working chambers, the booster piston is boosted to the side of the low-pressure first working chamber, and the output member can be driven to give the transmission a predetermined shift operation. . Further, due to the atmospheric pressure difference between the first atmosphere chamber and the first reaction force chamber, the reaction force acts on the input member, so that the reaction force corresponding to the output of the booster piston is transmitted to the operator.

When the shift drive of the booster piston to the first working chamber side is completed, the first reaction force piston reaches the outer limit of movement and prevents further movement of the input member, so that the operator can know the end of shift. it can. Therefore, if the input to the input member is released, the first return spring returns the first reaction force piston to the inward movement limit, and accordingly, the first control valve moves to the first control valve.
Since the working chamber and the first reaction force chamber are made incommunicable with the negative pressure source and communicated with the first atmosphere chamber, the pressure between the first and second working chambers and between the first atmosphere chamber and the first reaction force chamber is reduced. The difference disappears,
The thrust of the booster piston and the reaction force of the first reaction force piston disappear, so that the booster piston and the input member can remain at the shift end position.

Thus, the distance between the pair of contact step portions of the input member with respect to the first and second reaction force pistons is set to be larger than the distance between the inward movement restricting portions of the first and second reaction force pistons. As long as the manufacturing error of the above is absorbed by the difference between the two distances, the two reaction force pistons have the elastic force of the first and second return springs in the free state of the input member without being interfered with by the regulating portion. The pair of abutting step portions are securely sandwiched to suppress axial rattling of the input member.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a booster shell 1 of a vehicle negative pressure booster B is fixed to an appropriate position of a vehicle body (not shown) at a mounting flange 1a at its right end. A booster piston 2 is slidably fitted in the booster shell 1,
As a result, the inside of the booster shell 1 is divided into a left first working chamber 3 ₁ and a right second working chamber 3 _{2 in} the figure.

The booster piston 2 is provided with cylindrical connecting flanges 4 ₁ and 4 ₂ projecting from the left and right end surfaces thereof, and the first and second valve cylinders 5 ₁ and 5 ₂ are provided on these connecting flanges 4 ₁ and 4 ₂ , respectively. is secured by a plurality of rivets 6 _and 62 together are fitted. These valve cylinders 5 ₁ and 5 ₂ are arranged so as to slidably pass through the left and right end walls of the booster shell 1, respectively.

Bearings 10 ₁ and 10 ₂ are screwed to the outer ends of the first and second valve cylinders 5 ₁ and 5 ₂ , respectively, and an input member that penetrates the valve cylinders 5 ₁ and 5 ₂ by both bearings 10 ₁ and 10 ₂ . 11 is slidably supported.

The input member 11 is connected to the speed change lever 12 at its right end. Also, the output member 3 formed integrally with the left bearing 10 ₁
A gear shift arm 39 is attached to the transmission 8.

The first and second reaction force pistons 7 ₁ and 7 ₂ are slidably fitted in the first and second valve cylinders 5 ₁ and 5 ₂ . Then, the first reaction force piston 7 ₁ moves in the first valve cylinder 5 ₁ into the first atmosphere chamber 13 ₁ on the bearing 10 ₁ side.
And the first reaction force chamber 14 ₁ on the booster piston 2 side. Further, the second reaction force piston 7 ₂ has a bearing 10 inside the second valve cylinder 5 ₂ .
A second air chamber 13 ₂ of ₂ side, to define a second reaction chamber 14 ₂ and the booster piston 2 side. Atmosphere introduction holes 15 ₁ and 15 ₂ are provided in the corresponding atmosphere chambers 13 ₁ and 13 ₂ for the bearings 10 ₁ and 10 ₂ , respectively.

The first and second reaction force chamber 14 _1, 14 ₂ are respectively communicated with the through hole 16 _1, 16 ₂ via the first and second working chambers 3 _1, 3 _2. Second
As shown in the figure, the through holes 16 ₁ and 16 ₂ are provided with the rivets.
Similar to the holes for 6 ₁ , 6 ₂ , the connecting flanges 4 ₁ , 4 ₂ and the valve cylinder 5 ₁ ,
It is drilled through 5 ₂ .

Referring again to FIG. 1, the first and second reaction force pistons 7 ₁ , 7 ₂
The first and second valve cylinders so as to face their inner end surfaces.
An annular shoulder as a restricting part formed on the inner peripheral surface of 5 ₁ , 5 _2.
8 ₁ , 8 ₂ and the bearing 10 so as to face the outer end surfaces thereof.
It is possible to slide the fixed stroke l ₁ defined by the cylindrical stoppers 9 ₁ and 9 ₂ formed at the inner ends of ₁ and 10 ₂ .
That is, the reaction force pistons 7 ₁ and 7 ₂ are regulated in the inward movement limit by the shoulders 8 ₁ and 8 _{2 and} are regulated in the outward movement limit by the stoppers 9 ₁ and 9 ₂ .

The first and second reaction force pistons 7 ₁ and 7 ₂ have a shallow circular recess 1 that is concentric with the corresponding reaction force piston and opens at the outer end surface thereof.
8 _1, and 18 _2, the recess 18 _1, 18 ₂ valve chamber 19 ₁ which opens into the bottom surface eccentric location of, and 19 _2, the valve seat 20 ₁ of the valve chamber 19 _1, 19 _2, 20 ₂ valve which penetrates the Holes 21 ₁ and 21 ₂ are provided. In the valve chambers 19 ₁ and 19 ₂ , the valve holes 21 ₁ and 21 ₂ are opened and closed in cooperation with the valve seats 20 ₁ and 20 ₂ .
The first and second poppet valves 22 ₁ and 22 ₂ and the valve springs 23 ₁ and 23 ₂ for biasing them in the valve closing direction are housed. The valve rods 24 ₁ and 24 ₂ of the first and second poppet valves 22 ₁ and 22 ₂ slidably pass through the valve holes 21 ₁ and 21 ₂ , respectively, and the first and second reaction force pistons 7 ₁ and 7 2. _{Although it} projects from the inner end surface of ₂ , the cross section is cross-shaped so as not to close the valve holes 21 ₁ and 21 ₂ (see FIG. 3).

Wherein the recess 18 _1, 18 _2, the holding plate 25 _1, 25 ₂ for supporting the valve spring 23 _1, 23 ₂ is incorporated fitted and held by the return spring 17 _1, 17 ₂ of the inner end. The return springs 17 ₁ and 17 ₂ and the holding plate
25 _1, 25 ₂ annular rib 26 ₁ to engage the fourth spring 17 ₁ back as shown in FIG, 17 ₂ of the inner end in the circumferential edge in order to stabilize the contact position with the 26 ₂ holding plate 25 ₁ , it is formed in 25 _2.

In this way, each holding plate 25 ₁ , 25 ₂ has a corresponding reaction force piston.
It is clamped by 7 ₁ , 7 ₂ and return springs 17 ₁ , 17 ₂ .

The holding plates 25 ₁ and 25 ₂ have housings 27 that follow the valve chambers 19 ₁ and 19 _2.
1 , 27 ₂ are formed so as to bulge toward the atmosphere chambers 13 ₁ , 13 ₂ side,
Holes 28 _1, 28 ₂ which opens to the atmosphere chamber 13 _1, 13 ₂ is provided in the housing 27 _1, 27 ₂ of the end wall. This housing 2
7 ₁ and 27 ₂ are loaded with filters 29 ₁ and 29 ₂ , and wire meshes 30 ₁ and 30 ₂ or perforated plates that hold the filters are attached to the housings 27 ₁ and 27 _2.
Is locked to the inner end of the.

Disc-shaped first and second flat valves 31 ₁ and 31 ₂ are respectively arranged in the first and second reaction force chambers 14 ₁ and 14 ₂ , and these flat valves 31 ₁ and 31 ₂ are the input members. 11 is slidably mounted on top.

The input member 11 is formed with a negative pressure introducing passage 32 that communicates with a negative pressure source S (for example, in the intake manifold of the engine). The negative pressure introducing passage 32 is provided at the center of the booster piston 2. It is in constant communication with the negative pressure chamber 33.

The first and second flat valves 31 ₁ and _{3 12} are valve seals that surround the negative pressure chamber 33 and can be seated on both end surfaces of the booster piston 2.
34 _1, 34 provided with a _2, when the valve seal 34 _1, 34 ₂ is seated on the booster piston 2, between a negative pressure chamber 33 and the reaction force chamber 14 _1, 14 ₂ is blocked from the booster piston 2 When they are separated, they communicate with each other. These flat valves 31
_A valve spring 35 _{1 is provided} between the reaction force pistons 7 ₁ and 7 ₂ and the flat valves 31 ₁ and 31 ₂ in order to constantly urge the valves ₁ and 31 ₂ in the valve closing direction, that is, the direction in which the booster piston 2 is seated. , 35 ₂ is provided in a compressed state. These valve springs 35 ₁ and 35 ₂ are set to have a smaller set load than the return springs 17 ₁ and 17 ₂ , so that the reaction force pistons 7 ₁ and 7 ₂ are moved outward by the valve springs 35 ₁ and 35 ₂ . It won't move.

Further, the first and second flat valves 31 ₁ and 31 ₂ can receive the valve rods 24 ₁ and 24 ₂ of the first and second poppet valves 22 ₁ and 22 ₂ . In particular, when the flat valves 31 ₁ and _{3 12} are seated on the booster piston 2, the reaction force pistons 7 ₁ and 7 ₂ are
When the flat valves 31 ₁ , 31 ₂ receive the valve rods 24 ₁ , 24 ₂ and come close to the inward movement limit where they abut the shoulders 8 ₁ , 8 ₂ of 5 ₁ , 5 ₂ , the poppet valves 22 ₁ , 22 are received. It is designed to open valve ₂ . that time,
The gap l ₂ between the poppet valves 22 ₁ and 22 ₂ and the valve seats 20 ₁ and 20 ₂ is set to be smaller than the stroke l ₁ of the reaction force pistons 7 ₁ and 7 ₂ .

Thus, the first poppet valve 22 ₁ and the first flat valve 31 ₁ constitute the first control valve V ₁ of the present invention, and the second poppet valve 22 1
The second control valve V ₂ is constituted by ₂ and the second flat valve 31 ₂ .

The input member 11 is formed with abutting step portions 36 ₁ and 36 ₂ that abut the inner end surfaces of the reaction force pistons 7 ₁ and 7 ₂ , respectively, and further includes the first and second flat valves 31 ₁ and 31 ₂ . Contact rings 37 ₁ and 37 ₂ facing each other with a gap l ₃ on the end face are provided.

Here, the distance S ₁ between the contact step portions 36 ₁ and 36 ₂ is the pair of shoulder portions that regulate the inward movement limit of the first and second reaction force pistons 7 ₁ and 7 _2.
8 _1, is set slightly larger than the ₈₂ between the distance S _2. The gap l ₃ is set to l ₁ > l ₃ > l ₂ .

A seal member 40 is attached to the booster piston 2 so as to be in close contact with the inner peripheral surface of the booster shell 1. Also in the end walls of the booster shell 1 seal member 41 closely respectively on the outer circumferential surface of the valve tube 5 _1, 5 ₂ is mounted. Further reaction force piston 7
_1, 7 _2, sealing member 43 closely respectively on the outer circumferential surface of the seal member 42 and the input member 11 closely respectively the inner peripheral surface of the valve tube 5 _1, 5 ₂ is mounted. Furthermore the flat valve 31 _1, 31 _2, the sealing member 44, 44 is mounted in close respectively to the outer peripheral surface of the input member 11. The dust boot 45, 45 are stretched respectively between the booster shell 1 and the bearing 10 _1, 10 _2.

Next, the operation of this embodiment will be described.

FIG. 1 shows the state of the negative pressure booster B when the speed change lever 12 is in the neutral position. In this state, the booster piston 2 occupies the center position in the booster shell 1 in the axial direction, and the first and second flat valves 31 ₁ and 31 ₂ are seated on both side surfaces of the booster piston 2, and the first and second flat valves
The reaction pistons 7 ₁ and 7 ₂ both come into contact with the shoulders 8 ₁ and 8 ₂ of the first and second valve cylinders 5 ₁ and 5 ₂ , and accordingly, the first and second poppet valves.
22 ₁ and 22 ₂ open the valve rods 24 ₁ and 24 _{2 received} by the flat valves 31 ₁ and 31 ₂ .

Therefore, each of the reaction force chambers 14 ₁ and 14 ₂ is blocked from the negative pressure chamber 33 while being communicated with the corresponding atmosphere chambers 13 ₁ and 13 ₂ , so that the reaction force chambers 14 ₁ , 14 ₂ and and the hole 16 _1, 16 first and second working _{chambers 2} communicating via a 3 _1, 3 _2, air chamber 13 _1, 13 ₂
In the same manner as above, the air is filled with the air introduced from the air introduction holes 15 ₁ and 15 ₂ . At that time, from the atmospheric chambers 13 ₁ and 13 ₂ to the reaction chamber 1
4 _1, air flowing through the 14 ₂ is filtered by the filter 29 _1, 29 _2. Further, the filters 29 ₁ and 29 ₂ also serve as a sound absorbing material that absorbs wind noise generated when air flows through the narrowed portions such as the valve holes 21 ₁ and 21 ₂ .

As a result, both the working chambers 3 ₁ and 3 ₂ and the atmosphere chambers 13 ₁ and 1 3
Since there is no atmospheric pressure difference between 3 ₂ and each of the reaction force chambers 14 ₁ and 14 ₂ , the input member 11 applies the force of the return springs 17 ₁ and 17 ₂ from the reaction force pistons 7 ₁ and 7 ₂ to each other. The contact step portions 36 ₁ and 36 ₂ receive and hold the contact step portions 36 ₁ and 36 ₂ .

From such a state, in order to establish the selected gear train of the transmission, if the input member 11 is moved to the left in the figure by the shift lever 12, for example, the input member 11 _first passes through the contact step portion 36 ₁ . the first reaction force piston ₇₁ by moved leftward Te, first
The poppet valve 22 ₁ closes and then the abutment ring 37 ₁ opens the first flat valve 31 ₁ as shown in FIG. During this period, the open state of the second poppet valve 22 ₂ and the closed state of the second flat valve 31 ₂ do not change.

As a result, the first reaction chamber 14 ₁ is cut off from the first atmosphere chamber 13 ₁ and communicates with the negative pressure chamber 33, so that the first reaction chamber 14 ₁ is connected.
14 ₁ and the first working chamber 3 ₁ , the negative pressure of the negative pressure source S is the negative pressure introduction path 3
2 and the negative pressure chamber 33. As a result, a large atmospheric pressure difference is generated between the first and second working chambers 3 ₁ and 3 ₂ , and the booster piston 2 receives a boosted pressure to the low-pressure first working chamber 3 ₁ side due to this atmospheric pressure difference. And follows the movement of the input member 11 to give a shift operation to the shift arm 39 via the output member 38.

During the above-mentioned movement of the booster piston 2, a pressure difference is generated between the first atmosphere chamber 13 ₁ and the first reaction force chamber 14 ₁ , so that this pressure difference is applied to the first reaction force piston 7 ₁ as shown in FIG. Then, it acts as a reaction force to the right and is transmitted to the input member 11, whereby the operator can obtain a good shift feeling.

When the leftward movement of the booster piston 2 is stopped due to the establishment of a predetermined gear train, the first reaction force piston 7 ₁ comes into contact with the stopper 9 ₁ as shown in FIG. 6, whereby the movement of the input member 11 is suppressed. Therefore, the operator can know the establishment of the gear train.

So if released input to the input member 11 from the shift lever 12, the first reaction force piston _71, the reaction force and the return spring
The force of 17 ₁ causes the first poppet valve 22 ₁ to return because it is returned together with the input member 11 until it comes into contact with the shoulder 8 ₁ of the first valve cylinder 5 ₁ again.
To the open state, the second flat valve 31 ₁ to the closed state, and the first reaction force chamber 14 ₁ and the first working chamber 3 _{1 become} the second reaction force chamber 14 ₂ and the second working chamber 3 respectively. It becomes atmospheric pressure as in ₂ .
In this way, since the equilibrium state of the atmospheric pressure is returned between both working chambers 3 ₁ and 3 _{2 and} between the atmospheric chambers 13 ₁ and 13 ₂ and the reaction force chambers 14 ₁ and 14 ₂ , the booster piston 2 and the input member 11 are You can stay in the shift end position.

When the speed change lever 12 is operated from the above state to the neutral position and further from the neutral position to the shift position on the opposite side to the above, the input by switching the second poppet valve 22 ₂ and the second flat valve 31 _2. Following the movement of the member 11, the booster piston 2 is actuated in the opposite direction to the above-described case, and the input member is operated until the operation is completed.
It will be understood from the above action that the reaction force is applied to 11.

When the speed change lever 12 is operated when the negative pressure disappears from the negative pressure chamber 33 due to the failure of the system of the negative pressure source S, the operation force is applied from the input member 11 to the reaction force piston 7 ₁ (or 7 ₂ ) and the stopper 9
Mechanical transmission to ₁ (or 9 ₂ ) and the output member 38 allows manual shifting of the transmission.

By the way, as described above, both contact step portions 36 ₁ , 3 of the input member 11 are
6 ₂ between the distance S ₁ is Ryobento 5 _1, 5 ₂ of the shoulder _81, 82 between the distance because it is slightly larger than the S _2, some manufacturing error of each part above two distances S _1, When the input member 11 is not actuated, that is, when the input member 11 is in a free state, the two reaction force pistons 7 ₁ and 7 ₂ have the shoulder portions 8 ₁ and 8 of the first and second valve cylinders 5 ₁ and 5 ₂ absorbed by the difference of S _2. Both contact step portions 36 ₁ and 36 ₂ can be reliably clamped by the elastic force of both return springs 17 ₁ and 17 ₂ without being interfered with by ₂ , and thus the axial direction of the input member 11 can be reduced. Tapping, that is, vibration is suppressed.

C. Effect of the Invention As described above, according to the present invention, during the shift of the transmission, the pressure difference corresponding to the thrust of the booster piston is used as the reaction force.
Alternatively, the second reaction force piston can be applied to give a good shift feeling to the operator, and after the shift, the reaction force disappears like the thrust of the booster piston. It is possible to avoid the delusion from the shift end position.

Also, in the free state of the input member, the two reaction force pistons always pinch the two contact step portions of the input member with the elastic force of the return spring regardless of the manufacturing error of each part. It is possible to suppress rattling and prevent vibration noise.

[Brief description of drawings]

The drawings show one embodiment of the present invention. Fig. 1 is a vertical sectional side view of a negative pressure booster for shifting, Fig. 2 is a sectional view taken along the line II-II of Fig. 1, and Fig. 3 is a perspective view of a poppet valve. FIGS. 4 and 5 are front views of the holding plate, and FIGS. 5 and 6 are operation explanatory views. B ...... vacuum booster, S ...... negative pressure source, S ₁ ...... both those Seddan unit distance, S ₂ ...... both restricting portions distance, V _1, V ₂ ...... first, second control valve , L ₁ …… Stroke 1 …… Booster shell, 2 …… Booster piston, 3 ₁ ,
3 ₂ ...... First and second working chambers, 5 ₁ , 5 ₂ ...... First and second valve cylinders, 7 ₁ ,
7 ₂ ...... First and second reaction force pistons, 8 ₁ , 8 ₂ ...... Shoulder, 9 ₁ , 9 ₂
…… Stopper, 10 ₁ , 10 ₂ …… Bearing, 11 …… Input member, 12
...... Gear shift lever, 13 ₁ , 13 ₂ ...... 1st, 2nd atmosphere chamber, 14 ₁ , 1
4 ₂ …… First and second reaction force chambers, 15 ₁ , 15 ₂ …… Atmosphere introduction hole, 1
7 ₁ , 17 ₂ ...... First and second return springs, 22 ₁ , 22 ₂ ...... First and second
Poppet valve, 31 ₁ , 31 ₂ ...... First, second ...... Flat valve, 32
...... Negative pressure introduction path, 33 …… Negative pressure chamber, 38 …… Output member, 39…
... shift arm

Claims (1)

[Scope of utility model registration request] 1. A negative pressure source (S); a booster shell (1)
A booster piston (2) reciprocally housed in the booster shell (1) and partitioning its interior into first and second working chambers (3 ₁ , 3 ₂ ); and this booster piston (2) First and second valve cylinders (5 ₁ , 5 ₂ ) projecting from both ends of the booster shell (1) and penetrating both end walls of the booster shell (1); and inside the first and second valve cylinders (5 ₁ , 5 ₂ ), respectively. It can move a fixed stroke defined by the inward movement limit on the booster piston (2) side and the outward movement limit on the opposite side, and moves inside the first and second valve cylinders (5 ₁ , 5 ₂ ). the first and second reaction force chamber of the booster piston (2) side, respectively (14 _1, 14 ₂₎ and the first and second atmospheric chamber on the opposite side (13 _1, 13 ₂₎ and the first and second partitioning in toward the first and second reaction piston (7 _1, 7 ₂₎ the inward movement limit, respectively; the reaction piston (7 _1, 7 ₂₎ and First and second return spring for biasing (17 _1, 17 ₂₎
And; a pair of abutment step portions (36 ₁ , 36 ₂ ) which slidably penetrate the first and second reaction force pistons (7 ₁ , 7 ₂ ) and can abut against the inner end of each reaction force piston. An input member (11) having a gear and connected to the speed change lever (12); first and second valve cylinders (5 ₁ , 5 ₂ )
When each reaction force piston (7 ₁ , 7 ₂ ) is located in the inward movement limit, the corresponding working chamber (3 ₁ ,
3 ₂ ) and the reaction force chambers (14 ₁ , 14 ₂ ) are not communicated with the negative pressure source (S) and are communicated with the respective atmospheric chambers (13 ₁ , 13 ₂ ), and the reaction force pistons (7 ₁ , 7 ₂ ) Is the contact step (36 ₁ , 36 ₂ ) of the input member (11)
Said outer each working chamber to be moved toward the moving limit by (3 _1, 3 ₂₎ and the reaction chamber (14 _1, 14 ₂₎ each air chamber (13 _1, 1
3 ₂ ) and first and second control valves (V ₁ , V ₂ ) that are in communication with the negative pressure source (S); output that is driven by the booster piston (2) to give a shift operation to the transmission Material (38)
And ;; and the distance (S ₁ ) between the pair of abutment step portions (36 ₁ , 36 ₂ ) of the input member (11) is set to the inside of the first and second reaction force pistons (14 ₁ , 14 ₂ ). Distance (S ₂ ) between a pair of restriction parts (8 ₁ , 8 ₂ ) provided on the first and second valve cylinders (5 ₁ , 5 ₂ ) to restrict the movement limit.
Negative pressure booster for shifting, characterized by being set larger.