JPH0629015B2 - Negative pressure booster negative pressure source device - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Field of Industrial Application The present invention relates to a negative pressure source device for a negative pressure booster, which operates a negative pressure booster by boost negative pressure of an engine, and more specifically, to apply a boost negative pressure to an intake system of an engine. The negative pressure chamber of the negative pressure booster is communicated with the negative pressure outlet hole provided for taking out through a one-way valve that allows the negative pressure to be transmitted only in one direction from the negative pressure outlet hole to the negative pressure booster side. Regarding the improvement of what was done.

The negative pressure booster is used, for example, to operate a master cylinder for a vehicle brake or a clutch.

(2) Conventional Technology In general, the magnitude of boost negative pressure taken out from the intake system of an engine varies depending on the type of engine and the type of auxiliary equipment.

However, since the boost limit point of the negative pressure booster depends on the magnitude of the negative pressure introduced into the negative pressure chamber, the boost negative pressure is introduced from the intake system of the engine where the boost negative pressure is relatively low to the negative pressure booster. In such a case, the boosting limit point of the negative pressure booster becomes a relatively small value, and the negative pressure booster stops its boosting function early at the time of input.
In particular, when the negative pressure booster is in a high load state, there is a problem that the boosting feeling is hindered.

Therefore, the air ejector was operated by the boost negative pressure of the engine, and the negative pressure larger than the boost negative pressure obtained by this was introduced into the negative pressure chamber of the negative pressure booster to raise the boost limit point of the negative pressure booster. A negative pressure source device has already been proposed (see, for example, Japanese Patent Laid-Open No. 60-29364).

(3) Problems to be Solved by the Invention However, since the air ejector has a drawback that it takes a long time to replenish the negative pressure, when the negative pressure booster is repeatedly operated in a high load region, the negative pressure from the air ejector is reduced. The supply of high negative pressure to the chamber may be delayed and the negative pressure consumption of the negative pressure chamber may not be sufficiently supplemented by the negative pressure, and the negative pressure booster may not be able to exert the desired boosting function.

The present invention has been proposed to solve such a problem, and even if the negative pressure booster is repeatedly operated in a high load region,
It is an object of the present invention to provide the negative pressure source device capable of always exhibiting a good boosting function.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides the negative pressure booster in which a boost limit point is determined by the magnitude of the negative pressure introduced into the negative pressure chamber. One direction in which a negative pressure is allowed to be transmitted from the negative pressure extraction hole to the negative pressure booster side in a negative pressure extraction hole provided for extracting the boost negative pressure to the intake system of the engine. In a negative pressure source device for a negative pressure booster, which communicates via a valve, an air ejector that generates a negative pressure higher than the boost negative pressure by the suction action of the boost negative pressure is connected to the intake system of the engine. A negative pressure accumulator capable of accumulating a negative pressure larger than the boost negative pressure in the negative pressure generation unit is provided via a one-way valve that allows transmission of the negative pressure only in one direction from the air ejector to the negative pressure accumulator side. Make it communicate with each other The negative pressure booster is connected to the negative pressure chamber of the negative pressure booster via a normally closed on-off valve, and the boost limit point of the negative pressure booster is set to the negative pressure of the negative pressure accumulator while the negative pressure booster is in a predetermined high load state. In order to raise the limit point corresponding to the pressure, the opening / closing valve outputs a valve opening signal for opening the opening / closing valve when it is detected that the negative pressure booster is in the predetermined high load state. It is characterized by connecting.

(2) Action When the negative pressure booster is in a low or medium load state, the negative pressure accumulator and the negative pressure chamber of the negative pressure booster are shut off by closing the opening / closing valve, so that the negative pressure chamber of the engine is closed. Boost negative pressure is stored, and this negative pressure boosts the negative pressure booster. In this case, even if the boost limit point is a value corresponding to the boost negative pressure, there is no practical problem because the negative pressure booster is not in the high load state. The high negative pressure generated by the air ejector is sufficiently stored in the negative pressure accumulator while the negative pressure accumulator is not used.

When the negative pressure booster enters a predetermined high load range, the open / close valve is opened by the valve opening signal output from the sensor, and the high negative pressure stored in the negative pressure accumulator is replenished to the negative pressure chamber of the negative pressure booster. The boost limit point can be raised from the value corresponding to the boost negative pressure to a relatively high value corresponding to the negative pressure of the negative pressure accumulator, so that the negative pressure booster repeatedly operates in the high load region and becomes negative. Even if a large amount of pressure is consumed, the negative pressure chamber can always be kept in a high negative pressure state in the high load region to keep the boost limit point of the negative pressure booster high.

Also, due to the interposition of the one-way valve between the air ejector and the negative pressure accumulator, there is no fear that the high negative pressure accumulated in the negative pressure accumulator will immediately flow out to the air ejector side even if the engine is stopped. Absent.

(3) Embodiment An embodiment in which the present invention is applied to an automobile braking device will be described below with reference to the drawings. First, in FIG. 1, a negative pressure booster B is supported by fixing a booster shell 1 to a vehicle body (not shown). It The inside of the booster shell 1 is partitioned by a diaphragm booster piston 2 into a front negative pressure chamber 3 and a rear control pressure chamber 4, and the negative pressure chamber 3 has a negative pressure from a negative pressure source device 5 of the present invention. Will be introduced. Control atmospheric pressure chamber 4
Is communicated with the atmosphere or the negative pressure chamber 3 in accordance with the advancing / retreating of the input rod 6 penetrating the rear wall of the booster shell 1, whereby the movement of the input rod 6 is followed between the two chambers 3, 4. A pressure difference is provided which enables the booster piston 2 to operate.

A brake pedal 7 for operating the input rod 6 is connected to the input rod 6, and a tandem master cylinder 8 operated by a booster piston 2 is attached to the front wall of the booster shell 1. When the master cylinder 8 is actuated by the booster piston 2, the master cylinder 8 outputs hydraulic pressure from the first and second output ports 9 ₁ , 9 ₂ and the corresponding wheel brakes 10 ₁ , 1 respectively.
Activate 0 ₂ .

Now, the negative pressure source device 5 will be described. The device 5 has an intake system 11 and an ejector 12 of the engine E as main components.

The intake system 11 of the engine E is composed of an air cleaner 13, a carburetor 14 and an intake manifold 15 which are sequentially arranged from the upstream side thereof. The intake manifold 15 has a structure for extracting boost negative pressure generated therein. A negative pressure extraction hole 16 is provided. The negative pressure extraction hole 16 communicates with a first negative pressure introduction hole 17 ₁ provided in the booster shell 1 and opening to the negative pressure chamber 3 via a negative pressure conduit 18, and the negative pressure conduit 18 is connected to the negative pressure conduit 18. From the pressure extraction hole 16 to the first negative pressure introduction hole 17 ₁
A one-way valve 19 which allows the transmission of negative pressure to only one direction is interposed.

The booster is shell 1, the second negative pressure introduction hole 17 ₂ is provided opening into the first negative pressure introduction hole 17 ₁ in the same manner as in the vacuum chamber 3, the negative pressure introduction hole 17 to the _second negative pressure conduit 20 A negative pressure accumulator 21 communicates with the negative pressure conduit 20, and an electromagnetic opening / closing valve 22 is provided in the negative pressure conduit 20.

The on-off valve 22 is of a normally closed type, and a pressure switch 23 as a sensor connected to the on-off valve 22 is installed in the master cylinder 8. When the hydraulic pressure in the master cylinder 8 rises above a predetermined value, the pressure switch 23 detects this as a boosting limit point of the negative pressure booster B depending on the boost negative pressure of the engine E, and sends it to the on-off valve 22. It is designed to output a valve opening signal.

The negative pressure accumulator 21 is communicated with a suction port 25 of the air ejector 12 through a negative pressure conduit 24, and the negative pressure conduit 24 is adapted to transmit the negative pressure from the suction port 25 to the negative pressure accumulator 21 only in one direction. A permitting one-way valve 26 is interposed.

The air inlet 27 of the air ejector 12 is connected to the air cleaner 13 or the upstream portion of the intake passage of the carburetor 14 via an air conduit 28. A negative pressure conduit 30 branched from the negative pressure conduit 18 is connected to the air outlet 29. The air outlet 29 may directly communicate with the intake manifold 15.

Next, the structure of the air ejector 12 will be described with reference to FIG. 2. In the main body 31 of the air ejector 12, the air inlet 27 opening on the right side surface thereof and the air outlet 29 opening on the left side surface thereof. , The suction port 25 opening on the upper surface thereof, and the decompression chamber 32 and the outlet chamber 33 as negative pressure generating portions connected to the suction port 25 and the air outlet 29, respectively.
And the diffuser 34 that communicates between the two chambers 32 and 33.
And are provided. The diffuser 34 includes a tapered taper portion 35 formed on one end surface of the decompression chamber 32, a divergent taper portion 36 formed on one end surface of the outlet chamber 33, and both taper portions 35,
It is composed of a throat portion 37 connecting between 36. In the decompression chamber 32, a nozzle 38 that is connected to the air inlet 27 and has its injection hole directed to the throat portion 37 is disposed in the vicinity of the tapered portion 35.

The operation of this embodiment will be described.

If a boost negative pressure is generated in the intake manifold 15 with the operation of the engine E, this negative pressure is taken out from the negative pressure extraction hole 16, and the negative pressure booster B is passed through the negative pressure conduit 18 and the first negative pressure introduction hole 17 _1. Is introduced into the negative pressure chamber 3 of the one-way valve 1
It is held in the chamber 3 by 9. In this way, the negative pressure in the negative pressure chamber 3 is first increased to the maximum boost negative pressure of the engine E.

Further, the boost negative pressure extracted from the negative pressure extraction hole 16 is also introduced into the outlet chamber 33 of the air ejector through the negative pressure conduit 30 and the air outlet 29, and acts on the injection hole of the nozzle 38 via the diffuser 34. With the suction force of this negative pressure, the nozzle 38 sucks the air filtered by the air cleaner 13 from the air conduit 28 and the air inlet 27 and injects it toward the diffuser 34, thereby generating a high-speed jet of air. The high negative pressure generated in the decompression chamber 32 by this high-speed injection is introduced into the negative pressure accumulator 21 through the suction port 25 and the negative pressure conduit 24, and the one-way valve 26 blocks the reverse flow. Thus, the negative pressure accumulator 21 stores a negative pressure larger than the maximum boost negative pressure of the engine E.

Now, in order to perform braking, if the brake pedal 7 is stepped on and the input rod 6 is pressed, the pressing force, that is, the input, is first determined by the boost negative pressure stored in the negative pressure chamber 3 in the negative pressure booster B. It is amplified with a predetermined boosting ratio up to the 1st boosting limit point P ₁ and output to the master cylinder 8 (FIG. 3).

When the negative pressure booster B reaches the first boosting force limit point P ₁ , the pressure switch 23 responds to the hydraulic pressure in the master cylinder 8 at that time and sends a valve opening signal to the opening / closing valve 22 to open it. A negative pressure larger than the boost negative pressure is introduced from the negative pressure accumulator 21 into the negative pressure chamber 3 through the negative pressure conduit 20, and the boost limit point is the second boost limit point P ₂ determined by the negative pressure of the negative pressure accumulator 21. Is raised to. As a result, the high load region where the negative pressure booster B can exert the boosting function is widened, and a good boosting feeling can be obtained even during sudden braking.

Meanwhile, normal braking is performed before the first fold force limit point P _1, is because it is rare that exceeding a first fold force limit point P ₁ emergency braking is performed, the use of negative pressure accumulator 21 The frequency is extremely low. Therefore, the air ejector 12
Since it takes a long time to replenish the negative pressure from the negative pressure accumulator 21 to the negative pressure accumulator 21, a large negative pressure can be sufficiently stored in the negative pressure accumulator 21 while it is not used. By any chance
Even when the rapid braking is repeated, the negative pressure consumption in the negative pressure chamber 3 is quickly replenished from the negative pressure accumulator 21 and the second boost limit point P ₂ can be maintained.

C. As described above, according to the present invention, when the negative pressure booster is in a low and medium load state, the negative pressure accumulator, the negative pressure booster, and the negative pressure chamber are shut off by closing the opening / closing valve, and Since the boost negative pressure of the engine is stored in the negative pressure chamber, the negative pressure can boost the negative pressure booster, and in this case, the boost limit point is a value corresponding to the boost negative pressure. However, since the negative pressure booster is not in the high load state, there is no problem such as impairing the boost feeling.
In addition, since the high negative pressure generated in the air ejector can be stored in the negative pressure accumulator while the negative pressure accumulator is not used, even if the negative pressure replenishment time by the air ejector takes a long time, a sufficient amount of accumulated pressure Can be secured.

Then, when the negative pressure booster enters a predetermined high load region, the opening / closing valve is opened to supply the high negative pressure accumulated by the negative pressure accumulator to the negative pressure chamber of the negative pressure booster. The booster boost limit point can be raised from the value corresponding to the boost negative pressure to a relatively high value corresponding to the negative pressure of the negative pressure accumulator, so that the negative pressure booster repeatedly operates in the high load region. Even if a large amount of negative pressure is consumed, the negative pressure chamber can always be placed in a high negative pressure state in the high load region, and the boost limit point of the negative pressure booster can be kept high. A good boosting feeling can be obtained. As a result, the negative pressure booster can be given a good boosting function according to the magnitude of its load, and in order to raise the boosting limit point, a relatively large and expensive atmospheric pressure difference generator such as a compressor. Since it is not necessary to provide specially or to specially modify the internal structure of the negative pressure booster, it is possible to greatly contribute to cost reduction and workability improvement such as assembly and disassembly.

Furthermore, due to the interposition of the one-way valve between the air ejector and the negative pressure accumulator, there is no fear that the high negative pressure accumulated in the negative pressure accumulator will immediately flow out to the air ejector side even if the engine is stopped. Therefore, the negative pressure booster can be started up faster when the engine is restarted.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of an essential part showing an embodiment of a negative pressure source device for a negative pressure booster according to the present invention, FIG. 2 is an enlarged vertical sectional view of an air ejector in FIG. 1, and FIG. It is a booster characteristic diagram of a booster. B ... Negative pressure booster, E ... Engine, 3 ... Negative pressure chamber, 5 ... Negative pressure source device, 6 ... Input rod, 8 ...
... master cylinder, 12 ... air ejector, 21 ... negative pressure accumulator, 23 ... pressure switch as sensor, 32 ... decompression chamber as negative pressure generating section

Claims (1)

[Claims] 1. A negative pressure chamber (3) of a negative pressure booster (B), the boost limit point of which is determined by the magnitude of the negative pressure introduced into the negative pressure chamber (3). The negative pressure extraction hole (16) provided for extracting the boost negative pressure to the intake system allows the transmission of the negative pressure only in one direction from the negative pressure extraction hole (16) to the negative pressure booster (B) side. In the negative pressure source device of the negative pressure booster, which communicates with each other through the one-way valve (19), air for generating a negative pressure larger than the boost negative pressure in the intake system of the engine (E) by the suction action of the boost negative pressure. A negative pressure accumulator (21) capable of accumulating a negative pressure larger than the boost negative pressure is connected to an ejector (12), and a negative pressure accumulator (21) is stored in the negative pressure generating portion (32) of the air ejector (12). From the negative pressure to the negative pressure accumulator (21) side only in one direction One-way valve tolerated (26) communicates via a normally closed on-off valve in the negative pressure chamber (3) of the negative pressure accumulator (21) negative pressure booster (B) (22)
And the negative pressure booster (B) is in a predetermined high load state, the boost limit point of the negative pressure booster (B) is a limit point corresponding to the negative pressure of the negative pressure accumulator (21) ( In order to raise the pressure up to P ₂ ), the on-off valve (22) has
A sensor (23) that outputs a valve opening signal for opening the opening / closing valve (22) when it is detected that the negative pressure booster (B) is in the predetermined high load state is connected. , Negative pressure source device of negative pressure booster.