JPS6155384A - Vacuum pump with diaphragm - Google Patents

Abstract

PURPOSE:To have a driver device in small size by furnishing an orifice for communication of inside the pump chest to its outside, and thereby lessening the driving torque at the time of starting the pump. CONSTITUTION:A vacuum pump is composed of No.1 housing 28, No.2 housing 26 and a disphragm 23. Exhaust chamber B is connected to the suction pipe of the engine through the exhaust port 33. A negative pressure shall be applied to actuator through the suction port 32. An orifice 31 is formed at No.2 housing 26 for communication of the pump chest A with its outside, and the starting torque is thus reduced.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a diaphragm type vacuum pump that obtains necessary negative pressure by displacement of a diaphragm, and particularly relates to a diaphragm type vacuum pump that suppresses the diaphragm drive torque at startup to a low level. This type of diaphragm vacuum pump is used as a negative pressure source to ensure negative pressure when engine negative pressure is insufficient.
For example, it is used in a vacuum type auto drive system or a brake booster.

[Prior Art] An example of the use of this type of diaphragm vacuum pump is an autodrive system.

When the driver sets the desired vehicle speed, the auto drive system automatically controls the vehicle speed and maintains a constant speed without pressing the accelerator pedal. Due to its control method, the auto drive system uses the rotation of the motor to adjust the throttle opening. There are two types: a motor-type vacuum pump that controls the throttle opening, and a vacuum-type vacuum pump that uses engine vacuum to control the throttle opening.The diaphragm-type vacuum pump of the present invention is used for the latter and the like.

This type of diaphragm vacuum pump is disclosed in Japanese Utility Model Publication No. 50-155610 and Japanese Utility Model Publication No. 58-3686.
Publication No. 7 can be mentioned.

The diaphragm vacuum pump described in these documents reciprocates the diaphragm to obtain the necessary negative pressure when the vacuum pressure reaches a predetermined value.

The use of this type of diaphragm vacuum pump in a vacuum autodrive system will be further described in detail with reference to the system diagram of the vacuum autodrive system shown in FIG.

Normally, the negative pressure in the intake manifold 1 is changed to the pressure in the manifold chamber 10a of the vacuum pump 1o by the piping 2, and the valve 11 is closed, and the actuator chamber 1
0b is set as a negative pressure, and the negative pressure is introduced into the actuator 5 through the piping 4. In order for the actuator 5 to pull the accelerator link using this negative pressure, a pressure equal to or lower than a predetermined arbitrary pressure (this is referred to as the a-layer Hg) is required. The actuator 5 is controlled by the controller 6.
Controls the opening degree of the throttle valve 7. If only the negative pressure of intake manifold 1 is used, tfJ actuator 5
When the required negative pressure cannot be obtained, the vacuum switch 8 detects this and sends the detection signal to the controller 6. The negative pressure shortage signal is sent to the motor 12 that is the drive source of the vacuum pump 10, and the motor 12 rotates the crankshaft of the vacuum pump 10, causing the diaphragm 13 to move up and down, and the valves 14 and 15 to move up and down. The opening and closing operations are performed to further reduce the negative pressure in the actuator chamber 10b and supply the negative pressure to the actuator 5.

The capacity of the vacuum pump 1o required at this time is just to be able to generate a negative pressure of a set pressure of 8 or more when the actuator 5 reaches its maximum discharge. Therefore, a vacuum pump having pump characteristics as shown in FIG. 4 is used.

[Problems to be solved by the invention] However, this type of diaphragm vacuum pump 10
As can be seen from the characteristic diagram, as the consumption flow of the actuator 5 decreases, the negative pressure generated increases.
In particular, since a large load is applied to the motor 12 as the drive source when starting the vacuum pump 10, it becomes necessary to increase the starting torque of the motor 12. Naturally, there were problems in that the motor had to be large and durable.

Therefore, an object of the present invention is to reduce the diaphragm drive torque at the time of starting a diaphragm vacuum pump and to downsize the drive device.

[Means for Solving the Problems] The present invention provides a system in which a diaphragm is displaced to open and close a discharge check valve and a suction check valve due to the change in volume of the diaphragm. It has an orifice through which it communicates.

[Operation] According to the above configuration, since the atmosphere is further introduced into the pump chamber when the diaphragm starts to be displaced, the starting torque for displacing the diaphragm can be reduced.

[Example 1] FIG. 1 shows a sectional view of essential parts of a diaphragm vacuum pump according to a first example of the present invention.

In the figure, the pump chamber Δ is formed between a diaphragm 23 and a second housing 26 made of a flexible material such as rubber. The diaphragm 23 is connected to the third housing 27
The peripheral portion thereof is held between the housing 26 and the second housing 26. The clamping pressure at the peripheral portion is obtained by screwing the first housing 28 and the third housing 27 together.
It may also be obtained by screwing with 7. Alternatively, other fixing means may be used. An end of a connecting rod 29 is fixed to the center of the diaphragm 23, and the other end of the connecting rod 29 is connected to a crank! It is pivotally supported by Ttl137. The crankshaft 37 is connected to the shaft of the motor 22, acts as a crankshaft of the vacuum pump, and moves the connecting rod 29 up and down as the motor 22 rotates. Since the fixed portion between the connecting rod 29 and the diaphragm 23 not only allows the connecting rod 29 to move up and down but also swings from side to side, the fixed portion simply makes the end of the connecting rod 29 and the diaphragm 23 integral. In addition, the structure is such that the diaphragm 23 is not damaged by the swinging. The motor 22 as the drive source may be an electromagnetic drive means that reciprocates using a solenoid.

Further, the second housing 26 is provided with a suction check valve 24 and a discharge check valve 25.
An orifice 31 is provided on the discharge check valve 25 side to communicate the pump chamber A with the atmosphere.

Then, an intake boat 32 connected to the actuator and an exhaust boat 33 connected to the intake manifold.
An exhaust check valve 21 mounted on a valve mounting member 34 that opens and closes by the negative pressure of the intake manifold is disposed between the actuator, and an intake boat 32, an exhaust check valve 21, and an exhaust boat 33.
The negative pressure of the intake manifold is led through.

Further, a filter 35 is disposed between the exhaust boat 33 and the exhaust check valve 21.

Note that the chamber that is formed between the exhaust boat 33 and the exhaust check valve 21 and which introduces the negative pressure of the intake manifold is hereinafter referred to as exhaust chamber B.

Between the intake boat 32 and the exhaust boat 33,
A chamber for introducing negative pressure to the actuator is formed between the exhaust check valve 21 and the valve mounting member 34 forming the exhaust chamber B, and the second housing 26. Hereinafter, this will be referred to as the intake chamber C.

In order to seal the intake chamber C, a ring 36 is interposed between the second housing 26 and the first housing 28. Further, the second housing 26 is provided with an orifice 31 that always communicates the atmospheric pressure and the internal pressure to the pump chamber with a given fluid resistance.

Note that the exhaust check valve 21, suction check valve 24, and discharge check valve 25 are known rubber-based valve bodies, and have a support part in the center, and an umbrella part around the support part opens and closes the communication hole. is configured to do so.

The diaphragm vacuum pump shown in FIG. 1 constructed in this manner can operate as follows.

Since the negative pressure in the intake manifold makes the exhaust chamber B negative pressure via the exhaust boat 33, the exhaust check valve 21 is closed and the negative pressure is guided to the actuator via the intake boat 32. Normally, the negative pressure in the intake manifold is directly guided to the actuator and used to control the opening and closing of the throttle valve.

When a situation arises in which the negative pressure in the intake manifold is insufficient, the motor 22 rotates, the diaphragm 23 is displaced, and the negative pressure in the intake chamber C is further reduced by the pump chamber A. For example, when the pump chamber A expands, the suction check valve 24 opens to reduce the pressure inside the intake chamber C, and when the pump chamber A is compressed, the discharge check valve 25 opens and the pressure inside the pump chamber A decreases. Venting pressure to atmosphere.

However, when the diaphragm vacuum pump of this embodiment is used in an autodrive system,
When the vehicle is driven at a predetermined speed and is forced to decelerate unexpectedly, the resume switch is turned on and when the vehicle returns to the set predetermined speed, the amount of flow consumed by the actuator is small and the negative pressure in the intake chamber C is high. There are cases. At this time, when the vacuum pump is operated, the check valve 24 will not open unless the pressure in the pump chamber A becomes lower than the pressure in the intake chamber C, so the pump chamber A becomes sealed and the motor 2
7, the starting torque becomes extremely large.

In addition, when the connection point between the motor shaft 37 of the vacuum pump and the connecting rod 29 rotates 90 degrees, that is, the connecting rod 29 moves up and down the diaphragm 23.
When the position of the connection point between the motor shaft 37 and the motor shaft 37 is expressed by its rotation angle θ as shown in FIG. 2, the maximum torque is required at the rotation position of the rotation angle 90 degrees.

The characteristics of the diaphragm vacuum pump shown on the left, which does not have the orifice 31 through which the pump chamber A communicates with the atmosphere outside the pump room, are as shown in the characteristic diagram of the vacuum pump without orifice shown by the solid line in FIG. 2. Become. To start the vacuum pump motor 22 under this condition,
The motor 22 requires a large starting torque.

However, in the diaphragm type vacuum pump of this embodiment, the pump chamber A is always connected to the pump chamber through the orifice 31 in the diaphragm type vacuum pump shown in the right figure, which is provided with an orifice 31 through which the pump chamber A communicates with the atmosphere outside the pump chamber. Since the atmosphere is introduced into the pump, the torque becomes as shown in the characteristic diagram of a vacuum pump with an orifice shown by the broken line in FIG. Even if the vacuum pump motor 22 is started with the connection point between the motor shaft 37 and the connecting rod 29 rotated 90 degrees, the atmosphere is introduced into the pump chamber A through the orifice 31, so when the vacuum pump is stopped, The pump chamber A is at a pressure equal to that of the atmosphere, and its starting torque can be reduced.

As described above, the diaphragm type vacuum pump of this embodiment is a diaphragm type vacuum pump having a pump chamber in which the diaphragm 23 is displaced and the discharge check valve 25 and the suction check valve 24 are opened and closed by the volume change. Since the orifice 31 is bored in the housing constituting the pump chamber, the pressure difference between the pressure in the pump chamber A and the atmospheric pressure is communicated by a specific fluid resistance, and the diaphragm type vacuum is always stopped. Since the pressure in the pump chamber A of the pump becomes equal to atmospheric pressure, the starting torque can be reduced.

In the first embodiment, the orifice 31 is bored in the second housing, but the orifice 31 is
Since it is sufficient to drill the orifice 31a between JA and atmospheric pressure, the orifice 31a may be bored in the connecting rod 29 as shown by the broken line in FIG.

[Effects of the Invention] As described above, since the diaphragm vacuum pump of the present invention is provided with an orifice through which the pump chamber communicates with the atmosphere outside the pump chamber, when the diaphragm vacuum pump is stopped, the The pump chamber A is in a pressure state equal to or substantially equal to the atmosphere, and its starting torque can be reduced. In addition, the drive source of the diaphragm vacuum pump can be downsized.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of essential parts of a diaphragm vacuum pump according to the first embodiment of the present invention, Fig. 2 is a characteristic diagram of the diaphragm vacuum pump, and Fig. 3 is a diaphragm vacuum pump used in a vacuum autodrive system. The system diagram shown in Figure 4 shows the pump characteristics of the vacuum pump. In the figure, 23... diaphragm, 24... suction check valve, 25... discharge check valve, 26... second housing, 27... third housing, 28... first housing , Two... Connecting rod, 31.31a... Orifice, A... Pump chamber, B... Exhaust chamber, C... Intake chamber. In addition, in the figures, the same reference numerals and the same symbols indicate the same or equivalent parts.

Claims (3)

[Claims] (1) In a diaphragm vacuum pump equipped with a pump chamber that opens and closes a discharge check valve and a suction check valve according to a volume change of the diaphragm when the diaphragm is displaced, an orifice through which the pump chamber communicates with the atmosphere outside the pump chamber. A diaphragm-type vacuum pump characterized by having a hole. (2) The orifice is formed by being bored in a housing that forms a pump chamber.
Diaphragm type vacuum pump as described in section. (3) The diaphragm vacuum pump according to claim 1, wherein the orifice is formed in a connecting rod that displaces the diaphragm.