JPS58214003A - Negative pressure servo motor - Google Patents

Abstract

PURPOSE:To achieve accurate positioning control of a diaphragm regardless of any variation in load weight by providing both a leak passage provided with a valve unit arranged on a diaphragm face of a diaphragm mechanism and an actuator which opens and closes the valve. CONSTITUTION:When a load applied to a servo motor is increased, a diaphragm 10 is moved rightward. A valve unit 23 therefore comes close to a leak passage 17 to reduce the inflow of atmosphere into a negative pressure chamber 12 so that a negative pressure therein is intensified to move the diaphragm 10 leftward again. If the load is reduced, the valve unit 23 goes apart from the passage 17, however, it is returned to the original position. When a signal negative pressure is weekened, a signal diaphragm 18 serving as an actuator is moved leftward to bring the valve unit 23 to the proximity of the leak passage 17, hence intensifying a negative pressure in the negative pressure chamber 12 to move the diaphragm 10 leftward. This is similar when the signal negative pressure is increased. Resultantly, the diaphragm 10 comes to a stop in position, and meanwhile, follows the diaphragm 18 which is operated by signal negative pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a negative pressure servo motor, and more particularly to a negative pressure servo motor comprising a diaphragm mechanism capable of performing positive IN position control.

FIG. 1 shows a conventional negative pressure servo motor having a diaphragm mechanism. This is configured such that a diaphragm 1, a cover 2, and K form an airtight negative pressure chamber 3, and negative pressure from a negative pressure source is introduced into this negative pressure M3. Then, a spring 4 is interposed between the inner surface of the diaphragm 1 and the inner surface of the cover 2 opposing the diaphragm 1 inside the negative royal chamber-3,
Also attached is an actuating shaft 5 which is connected to the diaphragm IKti load. Therefore, in this negative pressure servo motor, position control is performed by balancing the load acting on the surface of the diaphragm 1 due to the negative pressure in the negative pressure chamber 3 and the load connected to the operating shaft 5. .

However, in the conventional negative pressure servo motor described above, there is a problem in that position control cannot be performed accurately if there is a difference in the load during the reciprocating stroke of the diaphragm l. For example, in a throttle valve shaft in a carburetor of an internal combustion engine, there is a large difference in rotational torque between the valve closing direction and the valve opening direction. Therefore, when the negative pressure servo motor is used to control the position of the throttle valve shaft, the relationship between the negative pressure and the stroke of the diaphragm 1 is not directly proportional, but the relationship shown by the large hysteresis curve shown in FIG. becomes. Therefore, although this type of negative pressure servo motor has the great advantage of being able to easily obtain a large force, it has not been put to practical use because of the major obstacle of not being able to accurately control the position. It was there in the past.

The present invention has focused on the above-mentioned conventional problems, and an object of the present invention is to provide a negative pressure servo motor that can perform accurate position # even when the load fluctuates.

Ninthly, to achieve the above object, the negative pressure servo motor according to the present invention is constructed by providing a leak passage with a valve device U interposed on the diaphragm surface of the diaphragm mechanism, and an actuator for opening and closing the valve. be.

With this configuration, the valve is opened and closed by the actuator in response to changes in the load, and the negative pressure in the negative chamber is adjusted via the leak passage, thereby accurately controlling the position of the diaphragm that is linked to the load. be able to.

Embodiments of the negative pressure servo motor according to the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a schematic cross-sectional view of the negative pressure servo motor according to this embodiment. As shown in the figure, this negative pressure servo motor has a driving diaphragm mechanism #lk that is operated by negative pressure from a negative pressure source.

This driving diaphragm mechanism is constructed almost in the same way as a conventional negative pressure servo motor (FIG. 1).

That is, the drive diaphragm 10't-cover 11 and K form a drive negative pressure chamber 12, and the cover 11 is provided with an introduction pipe 13 for introducing all of the drive negative pressure into the drive negative pressure chamber 12. In the driving negative pressure chamber 12, a compression spring 14 is interposed between the inner surface of the driving diaphragm 10 and the inner surface of the cover 11. Further, a frame 16 is attached to the outer surface of the driving diaphragm 10 to which an operating shaft 15 linked to a load is fixed, and is capable of reciprocating movement integrally with the diaphragm 10. Therefore, by introducing negative pressure into the driving negative pressure chamber 12, the driving diaphragm 10 is actuated, and the frame 16 and the actuating shaft 15 make a reciprocating sound accordingly.

In such a drive diaphragm mechanism I/), a leak passage 17 is formed in the center of the drive diaphragm lO, which communicates the drive negative pressure chamber 12 with the outside. A signal diaphragm mechanism as an actuator is provided with a valve mechanism for opening and closing this leak passage 17. This signal diaphragm mechanism has a signal diaphragm 18 facing the drive diaphragm 10, and a signal negative pressure chamber 20 by a cover 19.
It is formed by forming. The cover 19Fi of this signal diaphragm mechanism is integrally combined with the cover 11 of the drive diaphragm mechanism and fixed.
The signal diaphragm 18 is operated by a signal negative pressure introduction pipe 21 provided at the signal diaphragm 19. Furthermore, inside the signal negative pressure chamber 20, a compression spring 22 is interposed between the inner surface of the signal diaphragm 18 and the inner surface of the cover 19, and the compression spring 22 and the signal negative pressure are in parallel. The position of the signal diaphragm 18 is set.

By the way, the signal diaphragm 18 facing the drive diaphragm 1O is provided with a valve element 23 at a position corresponding to the leak passage 17 for opening and closing the leak passage 17t. Accordingly, the leak passage 17 is opened and closed by the operation of the valve body 23Fi signal diaphragm 18.

Here, the driving negative pressure introduced into the driving negative pressure chamber 12 is usually a negative pressure higher than the minimum negative pressure that can overcome the load applied to the actuation shaft 15, and the signal negative pressure introduced into the signal negative pressure chamber 20. This is to provide negative pressure to the signal diaphragm 1st at a predetermined position.

Then, a load is applied to the operating shirt 15 as a controlled object.

The negative pressure servo motor configured in this manner operates in the following manner. That is, when each diaphragm mechanism is in a stopped state with a lance, the state becomes as follows when the load changes and the signal negative pressure as a control signal completely changes.

(1) When the load increases, the driving diaphragm 1° moves to the right in FIG. As a result, the leak passage 17
Since the valve body 23 approaches the valve body 23, the amount of air flowing into the drive negative pressure chamber 12 decreases, and the negative pressure in the drive negative pressure chamber 12 increases. Therefore, the driving diaphragm 10 is pulled back to the left in the figure and held at the set position.

(2) Conversely, when the load decreases, the driving diaphragm 10 moves to the left in the figure. As a result, the leak passage 17 and the valve body 23 are separated, the amount of air flowing into the drive negative pressure chamber 12 increases, and the negative pressure in the drive negative pressure chamber 12 decreases. Therefore, the drive diaphragm lO is returned to the right in the figure and is also held in place.

(3) Next, when the old negative pressure decreases, the signal diaphragm 18 moves to the left in the figure. Since the leak passage 17 and the valve body 23 become closer to each other, the amount of air flowing into the drive negative pressure chamber 12 decreases, and the negative pressure in the drive negative pressure chamber 12 increases. Therefore, the driving diaphragm 10 moves to the left in the figure and is held in a fixed position. (4) Furthermore, when the signal negative pressure increases, the signal diaphragm 18 moves to the right in the figure, and this The leak passage 17 and the valve body 23 are separated from each other by nK, and the negative pressure in the drive negative pressure chamber 12 decreases. Therefore, the driving diaphragm 10 moves rightward in the figure and is held at the set position.

For this reason, the present embodiment is configured to move the driving diamond slam 10 in a direction that cancels out any disturbance if any disturbance occurs. Therefore, the driving diaphragm 10 always balances at a predetermined position and has the function of following the movement of the signal diaphragm 18 at the same time as being stationary. Therefore, by fully controlling the signal negative pressure, it is possible to move the driven body to an accurate position without being affected by load fluctuations.

Next, FIG. 4 shows a second embodiment of the present invention. This embodiment is based on the operating shaft 15 and frame 1 of the first embodiment.
6, the bushing rod 24 is passed through the drive negative pressure chamber 12 and the cover 11'ft:X to generate a driving force as an extrusion force. For this reason, it is configured so that it penetrates through the cover 11 via a seal 25 and is further held by a bearing 26 outside the cover 11. In such an embodiment, the driving force can be made to act as a pushing force, and the mounting is effective when there are the above restrictions.

In addition, the above-mentioned No. 1. In the second embodiment, the leak passage 17
If the parallelism between the needle valve 27'lt and the valve body 23 that opens and closes it is unstable, attach the needle valve 27'lt to the driving diaphragm 10 as shown in FIG.
The leak passage 17 may be opened and closed by the needle valve 27 by being in constant contact with the needle valve 27.

Further, FIG. 6 shows a third embodiment of the present invention. The internal pressure servo motor according to this embodiment is provided with a diaphragm mechanism for an external pressure signal of the cover 11 in the drive diaphragm mechanism, and a valve device is independently attached to the drive diaphragm 10.

The signal diaphragm 18 is provided with a bushing rod 28 that penetrates the cover 11' and abuts the valve body 23. The valve device is provided with a valve spring 29 so as to always close the leak passage 17. Such an embodiment has the advantage that the attachment of the diaphragm mechanism as an actuator becomes easier.

Furthermore, FIG. 7 shows a fourth embodiment of the present invention.

In this embodiment, the valve device in the third embodiment is attached to the signal diaphragm 18 side, and the rod for opening and closing the valve body 23 of this valve device is also used as the operating shaft 15 attached to the drive diaphragm 10. It is. For this purpose, a thin valve sleeve JO passing through the cover 11 of the driving diaphragm mechanism is attached to the signal diaphragm 18, and a vent hole 31 communicating with the outside is formed in this thin valve sleeve 30. Such an embodiment has the advantage that it is particularly advantageous against external contamination.

In the first to fourth embodiments described above, all of the embodiments have a structure in which changes in the drive negative pressure level are responded to by automatically adjusting the opening area.

Furthermore, FIG. 8 shows an example in which the negative pressure servo motor according to the above embodiment is applied as a throttle valve control mechanism of an internal combustion engine.

That is, the suction negative pressure is used as a drive negative pressure source, and the signal negative pressure is made constant using the suction pipe negative pressure as a source through a constant pressure valve 32, and this is created through a duty control solenoid valve 33t. be. In this application example,
For example, it is possible to easily configure a system that can obtain accurate engine rotation even when the load fluctuates.

Note that in all of the above embodiments, a diamond slam mechanism was used as the actuator, but this is not the only example; pulse motors, -
Of course, the same effect can be obtained by using other actuators such as DC=−.

As explained above, according to the present invention, since the covering part can be moved to an accurate position regardless of load fluctuation, a negative pressure servo motor using a simple diaphragm mechanism can be used, and the structure is simple and At the same time, it has the effect of achieving smaller size and lighter weight.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a conventional negative pressure servo motor, and FIG. 2 is a graph showing the relationship between negative pressure and stroke of the same device.
FIG. 3 is a schematic cross-sectional view of a negative pressure servo motor according to a first embodiment of the present invention, FIG. 4 is a schematic cross-sectional view of a negative pressure servo motor according to a second embodiment of the invention, and FIG. 6 is a cross-sectional view showing a schematic configuration of a negative pressure servo motor according to a third embodiment of the present invention, FIG. 7 is a cross-sectional view of a fourth embodiment of the same, and FIG. 8 is a cross-sectional view showing a modified example of the device. FIG. 2 is a configuration diagram in which a negative pressure servo motor according to an example is used to control a throttle valve of an internal combustion engine. DESCRIPTION OF SYMBOLS 10...Diaphragm for drive, 12...Driving negative pressure chamber, 17...Leak passage, 18...Diaphragm for signal, 1st/2nd negative pressure - 30th hole 70V , δ mouth/l

Claims (1)

[Claims] 1. A leak passage with a valve device interposed in the negative pressure chamber that operates the diaphragm of the tire slam mechanism is provided, and 5
A negative pressure servo motor equipped with an actuator that opens and closes the valve. 2. The negative pressure servo motor according to claim 1, wherein the actuator is formed of a diaphragm mechanism operated by a negative pressure signal. 3. The negative pressure servo motor according to claim 2, wherein both sets of signal negative pressures are obtained from a negative pressure source by a constant pressure valve and a duty control solenoid valve.