JPH0311936B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention is a tandem negative pressure doubler that generates braking force that can make the driver feel a corresponding feeling of anticipation of braking when the vehicle requires a large braking force. Relating to power devices.

Generally, the rotation of a car's wheels is braked by the driver stepping on the brake pedal, but air pressure or hydraulic pressure is used to boost the driver's depression force on the brake pedal to control the rotation of the wheels. A booster is used to ensure reliable braking. Among such boosters, the present invention particularly relates to a tandem negative pressure booster in which the boosting mechanism is doubled to increase the boost factor.

As a conventional tandem type negative pressure booster, there is one shown in FIG. 1, for example. In FIG. 1, 1 is a case, 2 is a master cylinder, 3 is a partition, 4 is a first diaphragm, 5 is a first chamber, 6
is a second chamber, 7 is a second diaphragm, 8 is a third chamber, 9 is a fourth chamber, and 10 is a valve means.

In such a conventional tandem type negative pressure booster, when the atmosphere is communicated with the third small chamber 8 by the valve means 10, the atmosphere is also communicated with the first small chamber 5 at the same time. As shown in FIG. 2, the tandem negative pressure booster had a linear characteristic in which the boost factor was constant. However, in a booster that has such a linear characteristic, the feeling of expectation that a human feels when applying the brake is, on the contrary, an upwardly convex double curve that decreases the boost factor, as shown in Figure 3. I feel the following curvilinear characteristics. Therefore, when braking the vehicle, there is a problem in that the expected braking force cannot be obtained and the feeling is poor.

This invention was made by focusing on these conventional problems, and it is a tandem type negative pressure booster that applies differential pressure to only one diaphragm when the brake pedal depression force or input is small. The purpose of this invention is to solve the above problem by providing a delay means that causes a differential pressure to act on both diaphragms when the input exceeds a predetermined value.

In other words, the tandem type negative pressure booster according to the present invention has the characteristics shown in FIG. It is intended to give a feeling of control.

The present invention will be explained below based on the drawings.

FIG. 5 is a diagram showing an embodiment of the present invention.

First, the configuration will be explained. In FIG. 5, 15 is a case with a space inside, and this case 1
5 is connected to a master cylinder 16. A partition wall 17 is fixed at a substantially central position inside the case 15, and this partition wall 17 divides the space inside the case 15 into two chambers. A first diaphragm 18 is supported in one chamber on the master cylinder 16 side of the internal space of the case 15 so as to be movable in the axial direction.
At the same time, one chamber of the space of the case 15 is defined into a first small chamber 19 and a second small chamber 20, which can be expanded and contracted by moving the first diaphragm. As will be described later, the first small chamber 19 can communicate with a negative pressure source 21 or the atmosphere, and the second small chamber 20 always communicates with the negative pressure source 21. First diaphragm 18 and case 1
A first diaphragm return spring 22 is interposed between the first diaphragm return spring 5 and the first diaphragm return spring 22 . A second diaphragm 23 is supported movably in the axial direction in the other chamber of the internal space of the case 15 on the opposite side to the master cylinder 16. The third chamber can be expanded and contracted by moving the second diaphragm 23.
It is divided into a small chamber 24 and a fourth small chamber 25. Second
A tube 26 is fixed to the axial portion of the diaphragm 23 on the master cylinder 16 side, and extends through the axial portion of the partition wall 17 . The third small chamber 24 can communicate with the negative pressure source 21 or the atmosphere as described later, and the fourth small chamber 25 can communicate with the second small chamber 20 and the cylinder 26.
It is always in communication with the negative pressure source 21 through the first passage 23a formed in the interior of the diaphragm 23 and the second diaphragm 23. A second diaphragm return spring 27 is interposed between the second diaphragm 23 and the partition wall 17. A reaction disk 30 is housed in the axis of the second diaphragm 23 on the master cylinder 16 side, and the surface of the reaction disk 30 on the master cylinder 16 side is brought into contact with the primary piston of the master cylinder 16 at one end. Disc portion 31 at the other end of the push rod 31
It is pressed by a. A valve plunger 32 is housed in an axial portion of the second diaphragm 23 so as to be slidable in the axial direction. reaction disk 3
One end of a valve plunger 32, which has a diameter smaller than the diameter of the disk portion 31a of the push rod 31, can come into contact with the surface opposite to the master cylinder 16 of the valve plunger 31. The other end of the valve plunger 32 is connected to the other end of a valve operating rod 33, one end of which is connected to a brake pedal (not shown). The second diaphragm 23 has a cylindrical portion 23b extending to surround the valve operating rod 33, and a first valve gear formed of an elastic material is provided on the inner surface of the cylindrical portion 23b of the second diaphragm 23. A proximal end portion of a poppet valve 34 as a mechanism is attached. A valve return spring 35 is interposed between the base end of the poppet valve 34 and the valve operating rod 33. The poppet valve 34 is the master cylinder 1
It has a tip surface 34a on the 6 side. A space 36 defined by the cylindrical portion 23b of the second diaphragm 23, the poppet valve 34, and the circumferential surface of the valve operating rod 33 communicates with the atmosphere. Second
A space 37 formed between the diaphragm 23 and the circumferential surface of the valve plunger 32 communicates with the fourth chamber 25 of the case 15 through a second passage 23c formed in the second diaphragm 23. Further, the space 37 also communicates with the third chamber 24 of the case 15. The third chamber 24 and the first chamber 19 of the case 15 communicate with a delay means 40 having a second valve mechanism 38 . The delay means 40 has a housing 41 having a space inside, and a third diaphragm 42 is supported in the housing 41 so as to be slidable in the axial direction. The third diaphragm 42 is a fifth diaphragm that can expand and contract the space inside the housing 41 together with the housing 41 by moving the third diaphragm 42.
It is divided into a small chamber 43 and a sixth small chamber 44. Fifth
The small chamber 43 communicates with the third small chamber 24 of the case 15, and the sixth small chamber 44 communicates with the first small chamber 19 of the case 15.
It communicates with The third diaphragm 42 is connected to the pressing means 46, and the third diaphragm 42
is pressed by this pressing means 46 in a direction such that the volume of the fifth small chamber 43 is reduced. The pressing means 46 includes a cylinder chamber 47, a piston 48, and a piston pressing spring 49.
The housing 41 and the cylinder chamber 47 are connected to the cylindrical member 5
The piston 48 and the third diaphragm 42 are connected by a first rod 52 and a second rod 53. 2nd rod 53
A second valve mechanism 3 is located near the first rod 52 around the periphery of the valve.
8, and a valve pressing spring 50 is interposed between the second valve mechanism 38 and the third diaphragm 42. The first rod 5 is installed in the cylinder chamber 47.
A hole 47a is formed so as to create a gap around the periphery of the cylinder chamber 47 and the second hole 47a.
A bellows 54 is interposed between the valve mechanism 38 and the valve mechanism 38 . The housing 41 has a bellows 54.
A hole 41 a is formed to provide a gap around the periphery of the bellows 54 , and the space between the cylindrical member 51 and the bellows 54 communicates with the negative pressure source 21 . The end surface 38a of the second valve mechanism 38 and the vicinity of the hole 41a of the housing 41 can come into contact with and separate from each other, and the end surface 38a of the second valve mechanism 38 and the end surface 52a of the first rod 52 can come into contact with each other and separate from each other.
It is possible to come into contact with and separate from the. A hole 38b is formed in the second valve mechanism 38 so that a gap is formed intermittently around the second rod 53, and a hole 38b is formed in the cylinder chamber 47 so that when the piston 48 moves against the piston pressing spring 49. A hole 47b is formed so that the space 55 within the bellows 54 communicates with the atmosphere.

Next, the action will be explained.

First, a case in which the driver does not press the brake pedal (not shown) will be explained. The first diaphragm 18 and the second diaphragm 23 are urged by the first diaphragm return spring 22 and the second diaphragm return spring 27 in a direction such that the volumes of the first small chamber 19 and the third small chamber 24 are reduced. Valve operating rod 3
3 is biased by a valve return spring 35 so as to protrude most toward the pedal (not shown).
Since the distal end surface 34a of the poppet valve 34 and a portion of the second diaphragm 23 near the space 37 are separated from each other, the fourth small chamber 25 and the third small chamber 24 communicate with each other through the second passage 23c and the space 37. In the delay means 40, since the third diaphragm 42 is urged by the piston pressing spring 49 in a direction such that the volume of the fifth small chamber 43 is reduced, the end face 38a of the second valve mechanism 38 and the housing 4
The space between the cylindrical member 51 and the bellows 54 and the sixth small chamber 44 are separated from the vicinity of the first hole 41a.
It is in communication with. From the above, case 15
The first small chamber 19, the second small chamber 20, the third small chamber 24,
The fourth small chamber 25, the fifth small chamber 43 of the housing 41,
And the sixth small chamber 44 are all in a negative pressure state because they communicate with the negative pressure source 21.

Next, a description will be given of when the driver depresses a brake pedal (not shown). When the valve operating rod 33 moves toward the master cylinder 16, first, the tip surface 34a of the poppet valve 34
comes into contact with a portion of the second diaphragm 23 near the space 37 and blocks the fourth small chamber 25 and the space 37. When the valve operating rod 33 further moves toward the master cylinder 16, the poppet valve 34
The tip portion 34a of the valve plunger 32 is separated from the valve plunger 32. As a result, the third small chamber 24 communicates with the space 36 through the space 37, and the internal pressure of the third small chamber 24 increases so as to approach atmospheric pressure. For this reason, the fourth small room 2
A differential pressure is generated between the valve operating rod 33 and the third small chamber 24, and the pedal force input through the valve operating rod 33 is boosted by this differential pressure and output to the master cylinder 16 through the push rod 31. When the internal pressure of the third small chamber 24 gradually increases and the volume of the third small chamber 24 expands to a predetermined amount, the internal pressure of the fifth small chamber 43 of the delay means 40 increases so as to overcome the biasing force of the piston pressing spring 49. The third diaphragm 42 moves in a direction to reduce the volume of the sixth chamber 44 while pushing the piston 48 through the second rod 53 and the first rod 52. When the piston 48 moves toward the piston pressing spring 49, the end surface 38a of the second valve mechanism 38 first comes into contact with a portion of the housing 41 near the hole 41a. For this reason, the 6th chamber 4
4 will be cut off from the negative pressure source 21. When the piston 48 further moves toward the piston pressing spring 49, as shown in FIG.
2a are separated from each other. And the sixth small chamber 44 is the hole 3
8b, the space 55, and the hole 47b to communicate with the atmosphere, and the internal pressure of the sixth small chamber 44 rises to approach atmospheric pressure. Therefore, the first case 15
A pressure difference will be generated between the small chamber 19 and the second small chamber 20, and this pressure difference, together with the pressure difference between the third small chamber 24 and the fourth small chamber 25, is inputted through the valve operating rod 33. Further increases the stepping force. The boosted force can then be output to the master cylinder 16 through the push rod 31. That is, by providing the delay means 40 that has such an effect, the tandem negative pressure booster has a nonlinear characteristic in which the boost factor rises halfway, as shown in FIG. .

In the above embodiment of the present invention, mechanical means as shown in FIG. 5 is provided as the delay means, but electrical means may be used as long as it can achieve the same purpose as the delay means. or other means are acceptable.

As explained above, according to the present invention, the configuration includes a case connected to a master cylinder and having a space inside, a partition wall fixed to the case and dividing the space into two chambers, and a partition wall supported by the case and having a space therein. a first diaphragm that is supported by the case and defines a first small chamber, one of which is expandable and contractable together with the case and can communicate with a negative pressure source or the atmosphere; and a second small chamber that is expandable and contractible and communicates with the negative pressure source; a second diaphragm that defines a third small chamber that can freely expand and contract the other chamber together with the case and communicate with a negative pressure source or the atmosphere, and a fourth expandable and contractible chamber that communicates with the negative pressure source;
A tandem negative pressure booster comprising: valve means capable of communicating the first small chamber and the third small chamber with the atmosphere when an input is applied; The third chamber is configured to include a first valve mechanism that connects the third chamber to the atmosphere or a negative pressure source when input cannot be applied, and a second valve mechanism that connects the first chamber to the atmosphere or the negative pressure source. When the input is smaller than a predetermined value, the first toilet mechanism connects the third small chamber to the atmosphere, and when the input exceeds the predetermined value, the first toilet mechanism connects the third small chamber to the atmosphere and operates the second valve mechanism. Since a delay means is provided to communicate one small chamber with the atmosphere, when braking the vehicle, the driver can obtain an optimal braking feeling by obtaining a braking force that increases rapidly compared to when the driver depresses the brake pedal strongly. You can get the effect that you can.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional side view of a conventional tandem type negative pressure booster, Figure 2 is a graph showing the characteristics of the boosting factor of the tandem type negative pressure booster shown in Figure 1, and Figure 3 is a graph showing the characteristics of the boost factor of the tandem type negative pressure booster shown in Figure 1. A graph showing the characteristics of the boost factor psychologically felt by the driver of the tandem negative pressure booster shown in the figure.
FIG. 4 is a graph showing the characteristics of the true boost factor of the tandem type negative pressure booster according to the present invention, and FIG. 5 is a cross-sectional side view of an embodiment of the tandem type negative pressure booster according to the present invention. , FIG. 6 is a cross-sectional side view showing the operating state of the delay device shown in FIG. 5. 15...Case, 16...Master cylinder, 1
7... Partition wall, 18... First diaphragm, 19...
...First chamber, 20...Second chamber, 21...Negative pressure source, 23...Second diaphragm, 24...Third chamber, 25...Fourth chamber, 34...Poppet valve (first valve mechanism) , 38... Second valve mechanism, 40... Delay means, 41... Housing, 42... Third diaphragm, 43... Fifth chamber, 44... Sixth chamber, 46... Pressing means.

Claims (1)

[Scope of Claims] 1. A case connected to a master cylinder and having a space inside, a partition wall fixed to the case and dividing the space into two chambers, and supported by the case so that one chamber can be expanded and contracted together with the case. a first diaphragm defining a first small chamber that can communicate with a negative pressure source or the atmosphere, and a second expandable and contractible chamber that communicates with the negative pressure source; a second diaphragm defining a third chamber in communication with a source of negative pressure or the atmosphere, and a fourth expandable chamber in communication with the source of negative pressure; and upon application of an input, the first chamber and the third chamber communicate with the atmosphere. In a tandem negative pressure booster, the valve means connects the third chamber to the atmosphere when an input is applied, and connects the third chamber to the atmosphere when no input is applied. the first connected to the pressure source;
a valve mechanism; and a second valve mechanism that communicates the first small chamber with the atmosphere or a negative pressure source; when the input is smaller than a predetermined value, the first valve mechanism communicates the third small chamber with the atmosphere; When the input exceeds the predetermined value, the third
A tandem type negative pressure booster, characterized in that a delay means is provided for communicating the small chamber with the atmosphere and operating the second valve mechanism to communicate the first small chamber with the atmosphere. 2. The delay means communicates with a housing having a space therein, a fifth chamber supported by the housing, which is expandable and retractable together with the housing, and which communicates with the third chamber, and the first chamber, and communicates with the atmosphere or a source of negative pressure. A third diaphragm defining a expandable and contractible sixth chamber and connected to the second valve mechanism; and a pressing means for pressing the third diaphragm in a direction in which the volume of the fifth chamber is reduced; When the volume of the fifth chamber is below a predetermined value, the second valve mechanism connects the negative pressure source to the sixth chamber and the first chamber, and when the volume of the fifth chamber exceeds a predetermined value, the second valve mechanism is switched to release the atmosphere. The tandem negative pressure booster according to claim 1, characterized in that the sixth small chamber and the first small chamber communicate with each other.