JPS5833922B2 - Vacuum increase device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for obtaining a negative pressure that is stronger than a negative pressure source in order to enhance the performance of equipment operated by the same.

In particular, it consists of a reciprocating power generating section driven by the negative pressure source, a vacuum pump mechanically interlocked with the power generating section, and a control valve device having a snap action mechanism that allows the power generating section to continue moving. This relates to a device that generates a negative pressure stronger than that of the negative pressure source.

Its features are its small size, simple and durable structure, and the ability to obtain negative pressure that is stronger than the negative pressure of the original constant negative pressure source without requiring any other power. An example in which the invention is most applicable to a vacuum brake booster for a vehicle will be described.

Conventionally, various types of power brakes have been used to increase braking force in vehicles, but vacuum booster brakes have also been used because of their simple structure.

Particularly in vehicles powered by internal combustion engines, vacuum brake boosters have been used that use intake pipe negative pressure as a negative pressure source.

In general, engine intake pipe negative pressure varies depending on usage conditions.
In some cases, only a weak negative pressure can be obtained, and the diameter of the booster, etc. must be increased to obtain the required acting force.

To avoid this, instead of using the intake pipe as a negative pressure source, it is necessary to use a more powerful negative pressure source, such as a vacuum pump driven by a belt from the engine, or a vacuum pump driven by another power source. There wasn't.

These negative pressure sources have various drawbacks, such as being constantly rotating, constantly under load, and having a complicated structure, making it difficult to meet severe demands for durability.

The present invention eliminates these drawbacks, uses only one intake pipe negative pressure as a power source, generates a negative pressure stronger than the intake pipe negative pressure, and
When strong negative pressure is obtained, it automatically stops operating, and when the negative pressure weakens, it automatically starts operating to obtain strong negative pressure.

That is, the object is to provide a device with a simple structure and a long service life that automatically shuts down only when necessary. Next, an embodiment of the present invention will be described with reference to the drawings.

In Fig. 1, A is a power generating section that uses negative pressure from a negative pressure source 1 as described later, B is a control valve that continues the reciprocating movement of the piston of the power generating section A, and C is a power generating section that uses the power from the power generating section A. This is the vacuum pump section that operates when the

In the power generation section, a cylinder section is formed by a large cylindrical shell 2 and an intermediate shell 3 having the same diameter as the large cylindrical shell 2, and a large power piston 7 is arranged inside.

Airtightness is maintained between the outer periphery of the large power piston 7 and the inner surface of the cylinder portion by a large diaphragm 12 made of an elastic material.

One end of the piston rod 9 located at the center of the large power piston 7 is slidably guided by a piston rod guide 10 provided at the center of the flange portion 3b of the intermediate shell 3, and further extends to reach the vacuum pump portion C. ing.

Flange portion 2b of large power piston 7 and large cylindrical shell 2
A second return spring 11 is disposed between the two and biases the large power piston 7 toward the intermediate shell 3.

The area on one side of the large power piston 7 surrounded by the large cylindrical shell 2, its flange portion 2b, the large diaphragm 12, and the large power piston 7 is a large pressure chamber 14, and the internal pressure Pv of the large power piston 7 is controlled by the operation of the control valve portion B. depending on the negative pressure P1 or atmospheric pressure P of the negative pressure source.

and changes. The other side of the large power piston 7, that is, the portion surrounded by the intermediate shell 3, its flange portion 3b, the large diaphragm 12, and the large power piston 7 is a first atmospheric pressure chamber 15, and a second atmospheric pressure chamber 15 provided in the intermediate shell 3 is The internal pressure is always atmospheric pressure P because it communicates with the atmosphere through the pores 3a.

It is. With this structure, the internal pressure of the large pressure chamber 14 is reduced to atmospheric pressure P.
.

, the large power piston 7 is pushed in the direction of the intermediate shell 3 by the force of the second return spring 11, and when the internal pressure becomes negative pressure P1, the large power piston 7 resists the force of the second return spring 11. It is moved to the large cylindrical shell 2 side.

The vicinity of the center of the flange portion 2b of the large cylindrical shell 2 protrudes toward the outside of the large pressure chamber 14 to form a large cylindrical shell hub (hereinafter referred to as hub) 22, inside which a control valve device whose details will be explained next is installed. It is stored.

The control valve device switches between negative pressure P1 coming in from the negative pressure inlet 23 from the negative pressure source 1 through the first check valve 24 and atmospheric pressure P1 coming in from the first atmospheric hole 22a provided in the large cylindrical shell hub 22. It is controlled and guided to the high pressure chamber 14.

The control valve device mainly consists of a valve seat 25, an air valve 27 for passing the atmosphere, and a vacuum valve 28 for passing negative pressure.

One end of the valve seat 25 is fixed around the inside of the negative pressure inlet 23 located on the center line of the flange portion 22b of the hub 22, and one end on the large pressure chamber 14 side is a planar valve seat 25b, with an opening in the center. It has a section 25a.

The middle portion is bellow-shaped and made entirely of elastic material.

A first return spring 26 is disposed between the valve seat 25b and the hub 22b, and the valve seat 25b is always connected to the large pressure chamber 1.
It is being energized towards number 4.

The main body of the air valve 27 has the shape of a stepped tube with both ends open, and the large diameter side is airtightly fixed to the large pressure chamber 14 side on the inner surface of the hub 22, and the small diameter side faces the valve seat 25b of the valve seat 25. It has an opening 27a.

The opening 27a is smaller in size than the valve seat 25b;
It is possible to complete the sealing by b.

The vacuum valve 28 is located inside the air valve 27 at one end of the valve operating frame 19, which is slidably fitted into the blind hole 18 bored on the axis of the piston rod 9, and is located at the valve seat. 25b.

The vacuum valve 28 is larger in size than the valve seat opening 25a, and the opening 25a can be sealed.

Based on the movement of the large power piston 7, the valve operating frame 19 moves to cause the end surface of the vacuum valve 28 provided at one end thereof to protrude from the opening 27a of the air valve 27 or to be retracted into the interior thereof.

That is, the structure includes a long groove 20 of a keyway provided in the axial direction on the outer periphery of the valve operating rod 19, and a stopper pin 21 fixed to the piston rod 9 whose tip protrudes and engages into the long groove 20. The relative movable distance of the stopper pin 21 (the diameter of the pin 21 less than the length of the long groove 20) is made equal to or slightly shorter than the allowable stroke length of the large power piston 7.

In addition, the valve operating frame 19 has a snap action,
An annular groove 31 on the toggle bar 29, toggle bar support 30, and valve actuating rod 19 is provided to provide two stable stopping positions at both ends of the stroke.

The toggle bar support 30 is made of rubber and is fixed to the inside of the large diameter portion of the near valve 2.

The outer side of the toggle bar 29 is fixed to the toggle bar support 30 by firing and faces in the radial direction, but the inner end of the toggle bar 29 is positioned closer to the monk than the bottom radius of the annular groove 31 in the radial direction.

Therefore, when the toggle bar 29 is oriented in the radial direction,
The toggle bar support 30 is severely compressed radially and becomes unstable with a large amount of energy.

In the two positions, front and back, where the toggle bar 29 is slightly inclined from the radial direction, the bottom surface of the annular groove 31 does not push the toggle bar 29, so the toggle bar support 30 is not compressed and is deformed according to the angle at which the toggle bar 29 is inclined. Since the toggle bar only has a small amount of energy, the toggle bar 2
It is more stable than when 9 points in the radial direction.

Therefore, the position of the annular groove 31, that is, the valve operating frame 19, has two stable positions on both sides of the central position where the toggle bar 29 faces in the radial direction.

If the valve operating frame 19 slides further, the inclination angle of the toggle bar 29 becomes a dog, and the inclination is limited by the width of the annular groove 31, and the sliding movement of the valve operating frame 19 is also limited.

When the toggle bar 29 is oriented in the radial direction, the seat surface of the vacuum valve 28 on the end face of the valve operating frame 19 is approximately coplanar with the seat surface of the air valve 27, so that the two stable parts of the valve operating frame 19 are In one position, the vacuum valve 28 protrudes beyond the air valve 27, and in the other position it enters the interior of the air valve 27.

If it is inside, the valve seat 25 is urged by the first return spring 26, and the valve seat surface 25
b corresponds to air balloon j27, vacuum balloon 7'2
8 and the valve seat surface 25b are apart.

In another stable position, that is, when the vacuum valve 28 protrudes from the air valve 27, the vacuum valve 28
is in contact with the valve seat surface 25b, and further in the direction shown in the figure.
It slides while compressing the return spring 26.

In this case, the air valve 27 is separated from the valve seat surface 25b, and the vacuum valve 28 is separated from the valve seat surface 25b.
That's right.

The movement of the valve actuating frame 19 between these two states is, since the center position is an unstable position, the movement of the valve operating frame 19 in either direction R shown in the figure, the movement of the valve operating frame 19 dramatically increases from the time the center position is exceeded. movement and snap action is performed.

If the valve seat surface 25b is made of a material with high elasticity such as rubber, the area in which both the vacuum valve 28 and the air valve 27 are in contact with the valve seat 25b near the center position will be long, which will prevent W-snap action operation. The start is certain.

The vacuum pump section C is arranged coaxially with the power generation section A, and includes an intermediate shell 4 having a smaller diameter than the large cylindrical shell 2 and the intermediate shell 3, and a small cylindrical shell 5 having the same diameter as the intermediate shell.
It has a cylinder portion consisting of , and a small power piston 8 is provided inside.

The small power piston arrangement is centrally fixed to a piston rod 9 extending from the power generating section, and its outer edge is connected to a small diaphragm 13 that maintains airtightness between the small power piston 8 and the cylinder.

One side of the small power piston 8 surrounded by the flange surface 3b1 of the intermediate shell 3, the small diaphragm 13, and the small power piston is a second atmospheric pressure chamber 16, the internal pressure of which is provided in the intermediate shell 4. Since the inside communicates with the outside atmosphere through the atmospheric hole 4a, the atmospheric pressure is always P.

It is. The other side of the small power piston 8, that is, the small cylindrical shell 5, the small diaphragm 13, and a small variable pressure chamber 17, which is a space surrounded by the small power piston 8, is formed.

A second check valve 32 that functions as a suction valve and a third check valve 33 that functions as a discharge valve are attached to the small variable pressure chamber 17.

The check valve 32 is connected to a negative pressure load 35, for example, a pipe 36 leading to a vacuum brake booster, and the check valve 3
3 is connected to a pipe 37 leading to the negative pressure source 1.

Therefore, the internal pressure Px of the small variable pressure chamber 17 is equal to the pressure P1 of the negative pressure source in the highest case, and equal to the pressure P2 of the negative pressure load 35 in the lowest case.

A fourth check valve 34 has a pipe 37 leading to a negative pressure source;
It is provided between the pipe 36 and the pipe 36 leading to the negative pressure load.

Therefore, it is also possible to suck air directly from the negative pressure load 35 without passing through the small variable pressure chamber 17.

Next, the effect will be explained.

The details will be explained later, but the operation of the power generating section A is controlled by the control valve section B, and generates power using negative pressure.
The vacuum pump section C functions as a vacuum pump that receives power from the power generation section A and sends gas to the negative pressure source 1 from the negative pressure load section 35 with strong negative pressure.

Now, when this device is in the state shown in Fig. 1, when negative pressure P1 is generated in the negative pressure source 1, the internal pressure Px of the small variable pressure chamber 17 and the internal pressure P2 of the negative pressure load immediately become Pl through the check valves 33 and 34. .

Further, in this state, the valve operating frame 19 is in the R side position in the figure out of two possible stable positions, and the valve operating frame 19 is in the R side position in the figure.
One end of the vacuum valve 28 is located to the right of the end surface of the air valve 27.

(Not outstanding.

) Therefore, the valve seat 25 is pushed by the first return spring 26 and comes into contact with the end surface of the air valve 27, thereby closing the opening of the air valve 27.

At this time, the end face of the vacuum valve 28 is connected to the air valve 2.
Since the valve seat 25 does not protrude beyond the end face of the valve 7, the valve seat 25 does not come into contact with the vacuum valve 28, and the valve seat opening 25a is open.

Therefore, inside the large pressure chamber 14, the vacuum valve 2
8 and the air valve 27 to communicate with the valve seat opening 25a, the internal pressure Pv is connected to the negative pressure source negative pressure P1.
is equal to

In this state, large power piston 7, small power piston 8,
Considering the balance of the forces acting on the weight of the piston that is integrally constructed from the piston rod 9, if the effective area of the large power piston 7 is A1 and the effective area of the small power piston 8 is A', then the force in the direction shown is is F = (Po'-・Pv) A'-(Po
'-Px)A''-f=(P□=P1)A
=(Po =P, )A/-f= (Po'-Pt
) (A"A') = f.

f is the reaction force of the second return spring 11.

In general, f can be kept sufficiently small, and P. 〉Pl, A>A
', so F > o and the piston weight starts moving in the direction shown, that is, to the left.0 When the piston weight moves in the direction shown, the volume inside the small variable pressure chamber 17 increases, and the internal pressure P2 of the negative pressure load 35 increases. At the same time, the internal pressure Px decreases from the initial Pl.

While the piston weight is moving to the left, F = (Po = Pt) A = (Po - P x
) If A'=f is F>0, the movement to the left continues, PX decreases, and if F=o, it stops automatically.

In this case, it is clear that P2=Px<Pl.

When the movement of the piston weight continues to the left end, the stopper pin 21 moving together with the piston weight hits the left end X of the long groove XY of the valve operating rod 19, and is held in one stable position by the toggle bar 29 and toggle bar support 30. When the operating frame, which had been previously held, is pushed in the L direction and further pushed by the movement of the piston weight, and the toggle bar 29 is tilted further from the radial direction, the toggle bar 29 is moved by the elasticity of the toggle bar support 30.
9 moves the valve operating frame 19 dramatically to the left to a stable position.

A so-called snap action is performed.

The state of the control valve section B after this snap action is performed is shown in FIG.

In this state, the valve operating frame 19 is in a stable position in the L direction, and the vacuum valve 2 has one end of the operating frame 19.
8 protrudes from the end surface of the air valve 27 and pushes the valve seat 25 to the left while compressing the first return spring 26.

That is, the valve seat opening 25a is closed by the vacuum valve 28, and the valve seat 25 is moved to the left to separate the air valve 27 and the valve seat 25, and the large pressure chamber 14 is closed by the passage between the air valve 27 and the vacuum valve 28. through the gap between the air valve 27 and the flat surface 25b of the valve seat 25 to communicate with the atmosphere, causing a large internal pressure P.
v is P.

becomes.

At this time, the force F that moves the piston weight to the right is P v
= Po so F==(Po-Pv)A+(Po-PX)A'+f=(
Po=Px)A'+f>0 This relationship holds that even if the small power piston 8 moves to the right and compresses the gas inside the small variable pressure chamber 17 and Px rises, the third check valve 33 is still present. Since PX does not become larger than the negative pressure source P1 and P x < P 1 < Po, this always holds true.

Therefore, in the state shown in FIG. 2, that is, if the valve operating frame is in a stable position on the left and the pressure of negative pressure source 1 is negative pressure P1,
The same operation is performed when the device is started, and even when the device is in operation, when the piston weight reaches the left end and causes the valve actuation frame 19 to snap action.

When the piston weight reaches the right end, the moving distance of the stopper pin 21 within the long groove 20 of the valve operating frame 19 is shorter than the stroke of the piston weight, so the operating frame is pulled to the right, which is opposite to the snap action described above. However, a similar snap action occurs due to the action of the toggle bar 29, the toggle bar support 30, and the valve operating frame annular groove 31, and the valve operating frame 19 is brought to the right stable position.

That is, the state returns to the state shown in FIG. 1, and the piston weight continues to move to the left.

By repeating this operation, the internal pressure P2 of the negative pressure load gradually decreases, and a pressure lower than the negative pressure source pressure P1 can be obtained.

If the value of P2 at this time is P2 min, then P2
min is the higher value of the two values that satisfy the following equation.

(a): (Po””-Px)A=(Po-P2
min ) A/-f=0(b) 2 P'``i'=
p m1nV2 Also, in equation b), vl is the minimum volume of the small variable pressure chamber 17, (2) is its maximum volume, and n is the polytropic expansion index.

When the value of P2 min that satisfies equation (a) is higher than the value of P2 min that satisfies equation (b), the force applied to the piston weight while the piston weight is moving in the direction shown in the figure, as explained earlier. is balanced and the piston weight stops.

This stopped state occurs when the negative pressure source pressure P1 decreases or when the negative pressure load 3
5 operates, its internal pressure P2 increases, and this continues until the balance shown in equation (a) is broken.

If the balance is broken, the piston weight begins to move as described above and continues to move until a new balance is achieved.

On the other hand, the value of P2min that satisfies formula (a) is
), the piston weight continues its reciprocating motion without stopping.

This means that when the volume of the small variable pressure chamber 17 is minimum, its internal pressure Px is equal to the negative pressure source negative pressure P1, the piston reaches the left end, the volume of the small variable pressure chamber 17 becomes maximum, and the pressure Px
This is because even when the piston is at its minimum, the forces applied to the piston's weight while moving to the left are not balanced.

Therefore, the value of P2 min that satisfies formula (a) is given by formula (b
) so that A is larger than the value of P2 min that satisfies
, A', flvl, ■2 design thread, AlP2 mi
When the value of n is reached, the piston weight stops moving.

Although one embodiment of the present invention has been described above, the power generating section A and the vacuum pump section C do not necessarily have to be on the same straight line, and the large power piston 7 is connected to a lever or the like.
It is also possible to link the small power piston 8 with the small power piston 8 and make each stroke different.

Now, to describe the effects of the present invention, with a simple and durable device, a negative pressure stronger than the negative pressure of an existing negative pressure source can be applied to a negative pressure load such as a vacuum tank or vacuum brake booster when the negative pressure of the vacuum tank or vacuum brake booster weakens. , can be obtained automatically.

Therefore, even if the negative pressure of the negative pressure source is weak, it is possible to generate a large force with a small actuator.

In particular, when used in braking-related applications, it greatly increases the performance and contributes to safety.

Moreover, this device requires less mechanical drive as a drive source than others, and has less power loss.

Moreover, it can be installed at any location in the middle of the piping from the negative pressure source to the negative pressure load, regardless of the location of other mechanical drive sources.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a state in which the weight of the piston is moving to the left, and FIG. 2 is a sectional view (partially omitted) showing the state in which the weight of the piston is moving to the right. 1: Negative pressure source, piston body, 1: Large power piston, 8
: Small power piston, 14: Large pressure chamber, 17: Small pressure change chamber, 19: Valve operating frame, 20: Long groove, 21: Stopper pin, 25: Valve seat, 25a: Valve seat opening, 27: Air valve, 28: Vacuum valve, 29 Nidoguru bar, 30 To Nidoguru bar support, 31: Valve operation frame annular groove, 32: Second check valve, 33: Third check valve, 34: Fourth check valve, 35: Negative pressure load.

Claims (1)

[Claims] 1 In a vehicle having a negative pressure source and a negative pressure actuator, a piston and a cylinder that generate power using negative pressure from the negative pressure source, a control valve that performs a snap action to control the reciprocating movement of the piston, and a negative pressure load that is generated by the power. Vacuum increase device consisting of a vacuum pump that pumps the gas on the side.