Acceleration And Deceleration Valve Apparatus

Abstract

Acceleration and deceleration valve apparatus having a housing body with a bore formed therein, a piston slidably inserted in the bore, a bias device for biasing the piston, a throttle device the opening of which is controlled by the piston, the piston dividing the bore into front and back chambers, an oil passage connecting the two chambers, a valve device provided in the oil passage, a pressure inlet for supplying oil to the oil passage, and an outlet for flowing out the oil through the throttle device.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an acceleration and deceleration valve apparatus for hydraulic position control and particularly to an acceleration and deceleration valve apparatus for hydraulic position control simple in construction and correct in operation.

2. Description of the Prior Art

A conventional acceleration and deceleration valve apparatus has the drawback that it is inaccurate in position control.

SUMMARY OF THE INVENTION

An object of this invention is to provide an acceleration and deceleration valve apparatus for hydraulic position control free from the drawback encountered in the prior art.

Another object of this invention is to provide an acceleration and deceleration valve apparatus for hydraulic position control simple in construction and easy in assembling and disassembling it.

A still further object of this invention is to provide an acceleration and deceleration valve apparatus for hydraulic position control accurate in operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram in cross-section illustrating an example of the present invention;

FIG. 2 is a cross-sectional schematic diagram showing another example of the present invention;

FIG. 3 is a schematic diagram in cross-section as in FIG. 2 except that the valve device is opened;

FIG. 4 is a cross-sectional schematic diagram showing still another example of this invention;

FIG. 5 is a cross-sectional schematic diagram as in FIG. 4 except that the valve device is opened; and

FIG. 6 is a graph used for explaining the operation of the example depicted in FIGS. 4 and 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 reference numeral 1 generally designates an example of acceleration and deceleration valve apparatuses for hydraulic position control of this invention. Reference character 1a shows the apparatus proper or a housing body of the valve apparatus 1. Reference numeral 4 represents a bore formed in the body 1a and reference numeral 6 a bore also formed in the body 1a. The bore 6 is smaller than the bore 4 in inner diameter and connected to the latter. Reference numeral 3 designates a piston which is inserted into the bore 4 and can be moved therein along a direction showed by an arrow a.sub.1. The piston 3 has provided with a projection 5 on its one side, namely on its right hand side in the example of FIG. 1. The diameter of the projection 5 is smaller than that of the piston 3. The projection 5 has formed on its free end portion a tapered portion designates at 5a which can be moved in the bore 6. Reference numerals 10 and 7 represent front and back oil rooms or chambers formed in the bore 4 by the piston 3. Reference numeral 2 designates a bias means such, for example, as a coiled spring located in the back chamber 7 around the projection 5 for normally biasing the piston 5 in the direction shown by an arrow a.sub.2, namely in the left hand direction in the figure. The projection 5 attached to the piston 3 has formed therein an oil passage 9 one opening 9a of which is opened in the back chamber 7 while the other opening 9b of which is opened in an oil chamber 8 formed in the sliding bore 6. Reference numeral 15 shows an annular groove formed in the body 1a around the bore 6 at the position corresponding to the root of the tapered portion 5a formed around the projection 5 when the piston 3 is positioned at the right hand end of the bore 4 against the spring force of the coiled spring 2. The annular groove 15 is connected to the bore 6 or the oil chamber 8 and forms a throttle device 16 in association with the projection 5, especially with its tapered portion 5a. The throttle device 16 is controlled by the movement of the piston 3 in opening.

Reference numeral 19 represents a pressure supply source and reference numeral 13 an pressure inlet formed in the body 1a which is connected to the pressure oil supply source 19 through, for example, a pipe 19a and also to the bore 4 at its front chamber 10 through an oil passage 13a formed in the body 1a. Reference numeral 12 shows a throttle formed in the oil passage 13a and reference numeral 11 a check valve formed in an oil passage 13b which is formed in the body 1a parallel with the oil passage 13a and through which the pressure inlet 13 is connected with the front oil chamber 10 of the bore 10. Reference numeral 14 designates a valve device such, for example, as a solenoid valve which connects the pressure inlet 13 with the oil chamber 8 of the bore 6 through oil passages 14a and 14b. The oil flowed into the oil chamber 8 through the solenoid valve 14 returns to an oil tank 18 through the throttle device 16 and an oil passage 17 formed in the body 1a and an oil passage 17a.

In the case where the solenoid valve 14 is closed as shown in the figure, the oil supplied to the pressure inlet 13 from the pressure supply source 19 flows into the front chamber 10 through the check valve 11 to shift the piston 3 to the right hand direction in the figure against the coiled spring 2. As a result, the projection 5 attached to the piston 3 is also shifted to the right hand direction in the bore 6 of a small diameter to substantially close the throttle device 16, which will means that no oil flows through the throttle device 16. In this case the spring force of the coiled spring 2 is selected in such a manner that when the solenoid valve 14 is opened and the rated oil flows through the solenoid valve 14 into the oil chamber 8, the spring force of the coiled spring 2 is large enough as compared with the oil pressure exerting on the piston 3 due to the inner pressure drop of the oil through the solenoid valve 14.

When the solenoid valve 14 is opened, when the pressure oil is fed to one oil chamber of the hydraulic actuator (not shown) upon the acceleration signal and the solenoid valve 14 is opened by connecting the outlet chamber thereof to the acceleration and deceleration valve, the oil flows to the oil chamber 8 of the bore 6 from the pressure inlet 13 through the oil passage 14a, the solenoid valve 14 and the oil passage 14b and the oil flowed into the oil chamber 8 flows into the tank 18 through the throttle device 16 which is opened little and the oil passages 17 and 17a. At this time the pressure difference between the front and back oil chambers 10 and 7 of the bore 4 divided by the piston 3 is substantially equal to the inner pressure drop in the solenoid valve 14. Thus, the piston 3 is moved to the left hand direction in the figure by the spring force of the coiled spring 2. The moving speed of the piston 3 to the left is determined by the throttle 12 formed in the oil passage 13a. As the piston 3 is moved to the left, the opening of the throttle device 16 is increased gradually to increase the flow rate of the oil through the throttle device 16. When the piston 3 arrives at the left hand end of the bore 4, the throttle device 16 is opened at its maximum. Thus, the piston of the hydraulic actuator can be moved at high speed following to the acceleration motion.

If the solenoid valve 14 is closed, i.e., if the piston of the hydraulic actuator (not shown) is moved to a predetermined position, the deceleration signal is produced by, for example, a limit switch and then the solenoid valve 14 is closed, no oil flows through it. Accordingly, the oil pressure in the chamber 7 is decreased to increase the pressure difference of the oils between the front and back chambers 10 and 7 over the spring force of the coiled spring 2. As a result, the oil flows into the chamber 10 through the check valve 11 to shift the piston 3 to the right. According to the movement of the piston 3 to the right, the opening degree of the throttle device 16 is decreased to decrease the flow rate of the pressure oil through the throttle device 16, by which the moving speed of the piston 3 to the right is made low. When the piston 3 reaches the right end of the bore 4 at low speed, its movement is stopped. The flow rate an amount of the oil flowed into the front chamber 10 during the movement of the piston 3 at decelerated speed to the right is a constant value determined in accordance with the amount of the moving volume of the piston 3. As set forth above, the deceleration operation of the piston 3 is carried out with the oil of a constant volume.

Accordingly, the deceleration distance of the piston of the hydraulic actuator (not shown) from the generation of the deceleration signal becomes also constant.

Another example of this invention will be explained hereinbelow with reference to FIGS. 2 and 3 in which reference numerals same to those of FIG. 1 show the same elements and their explanation will be omitted for the sake of brevity because they are substantially same in construction and operation.

In this example first and second check valves 21 and 22 are respectively provided in the body 101a instead of the biasing means such as the coiled spring 2 in the example of FIG. 1. The first and second check valves 21 and 22 are both closed when the differential pressure is lower than a set value, while opened when the differential pressure is higher than the set value. The first check valve 21 is located in the oil passage 13a for connecting the pressure inlet 13 with the front chamber 10, while the second check valve 22 is located in an oil passage 22a formed in the body 1a for connecting the back chamber 7 with an annular oil groove 26 formed in the body 1a around the bore 6 at the position adjacent to the groove 15 and at the right side with respect to the latter. Reference numeral 14e represents an oil passage which connects an oil outlet 13' of the passage 13a connected to the pressure inlet 13 with a first closed portion 14c of the solenoid valve 14, reference numeral 14f an oil passage which connects a second closed portion 14d of the solenoid valve 14 with an oil passage 20 formed in the body 101a and connected to the oil passage 22a and to the annular groove 26, reference numeral 14g an oil passage which connects the first closed portion 14c with an oil passage 28 formed in the body 1a and connected to the back oil chamber 7 and to the passage 22a, and reference numeral 14h an oil passage which connects the second closed portion 14d with a branch oil passage 27 formed in the body 101a and connected to the front chamber 10 and to the oil passage 13a. The check valve 11 and the throttle 12 used in FIG. 1 are omitted in this example.

The flow direction of the oil through the first check valve 21 from the pressure supply source 19 is selected in such a manner that the oil flowed into the pressure inlet 13 from the pressure supply source 19 passes to the front chamber 10 through the first check valve 21, while the flow direction of the oil through the second check valve 22 is selected in such a manner that the oil flowed into the oil passage 28 flows through the second valve 22 to the annular groove 26. Reference numeral 25 shows a top portion of a diameter substantially same to the inner diameter of the bore 6 which is attached to the free end of the projection 5. The oil passage 9 formed in the projection 5 passes through the top portion 25 and opens in the chamber 8 in the bore 6.

The solenoid valve 14 shown in FIG. 2 is closed, so that no oil passes through the solenoid valve 14 at this condition. If the solenoid valve 14 is opened as shown in FIG. 3, the oil supplied to the pressure inlet 13 from the source 19 through the pipe 19a flows into the back chamber 7 through the oil passage 14e, a first opened portion 14c' and the oil passages 14g and 28, while the oil in the front chamber 10 flows to the oil tank 18 through the oil passages 27, 14h, a second opened portion 14d', the oil passages 14f, 20, the throttle device 16 and the oil passages 17 and 17a. In this case the preliminary differential pressure values of the first and second check valves 21 and 22 are set in such a manner that when the rated amount of the oil is supplied to the solenoid valve 14, the both check valves 21, 22 are respectively opened by the differential pressure higher than the inner pressure drop of the oil through the solenoid valve 14.

When the solenoid valve 14 is opened and the piston 3 is moved to the left as shown in FIG. 3 at accelerated speed, the check valves 21, 22 are both closed. Accordingly, the oil from the front oil chamber 10 passes through the throttle device 16 only. As the piston 3 is moved to the left as in FIG. 3, the opening of the throttle device 16 is increased, whereby the flow rate of the oil therethrough is increased. When the piston 3 arrives at the left end of the bore 4, the opening of the throttle device 16 becomes at its maximum. At this time, the pressure differences of the oil between the pressure inlet 13 and the oil chamber 10 and between the oil chamber 7 and the oil passage 20 become large enough as compared with the set values of the check valves 21, 22, so that both the check valves 21, 22 are respectively opened to supply therethrough the oil from the pressure inlet 13 to the annular oil groove 26, whereby the acceleration of the movement of the piston 3 to the left is maintained to flow out therethrough the rated amount of the oil to the oil tank 18 through the oil passages 17 and 17a.

Following thereto, if the solenoid valve 14 is closed to prevent the oil from being passed therethrough, the oil passes from the pressure inlet 13 to the front oil chamber 10 through the first check valve 21 and the oil in the back oil chamber 7 flows out to the annular groove 26 through the second check valve 22. As a result, the oil in the front oil chamber 10 becomes higher than that in the back oil chamber 7 to move the piston 3 to the right in the figure with the result that the opening of the throttle device 16 is decreased and accordingly the amount of the oil passed therethrough is decreased. For this reason the moving speed of the piston 3 to the right becomes slow gradually and then the piston 3 reaches the right end of the bore 4 is the figure to stop its movement. Thus, the acceleration and deceleration of the moving speed of the piston 3 is carried out by the oil of a constant volume in this invention.

As set forth just above, according to this invention the right and left movements, namely the acceleration and deceleration movements of the piston 3 are practiced by the oil or that of the constant volume produced by the movement of the piston 3 by a constant length, so that the distance or range within which the piston movement is accelerated and decelerated can be made substantially constant. Accordingly, it may be apparent that the present invention is used for hydraulic position control apparatus with high accuracy and smooth position determination.

Further, the example shown in FIGS. 2 and 3 can be easily assembled and disassembled and small in size because there is employed no spring such as shown in FIG. 1.

FIGS. 4 and 5 show still another example of this invention in which reference numerals same to those of FIGS. 1, 2 and 3 represent the same elements and they are substantially same in construction and operation. For this reason, no detailed explanation will be given thereon.

In the example depicted in FIGS. 4 and 5 an oil passage 29 is provided in the body 1a which oil passage 29 connects the annular groove 26 with the oil passage 17 at its middle way. In the oil passage 29 there is provided a throttle valve such as, a needle valve 30 which can be controlled in its opening by, for example, hand from the outside of the body 1a. That is, the flow rate of the oil flowing through the throttle valve 30 can be easily adjusted.

Assuming that the throttle valve 30 is entirely closed and the opening of the throttle device 16 is in proportion to the position of the piston 3, the moving speed of the piston 3, in the other words the flow rate of the oil passing through the acceleration and deceleration apparatus is shown in FIG. 6 by a curves a, a' and a" in which the abscissa represents the time t and the ordinate the flow rate M of the oil. While, if the initial opening of the throttle device 16 is changed, the flow rate M of the oil changes in time lapse within the range shown by curves a' and a". For example if the initial opening of the throttle device 16 is substantially zero, the amount M changes in accordance with the curve a" with time lapse, which requires much time for acceleration.

In general, the acceleration conditions are different for respective position control device, so that it may be desired that the initial opening of the throttle device 16 can be varied.

Curves b, b' and b" in FIG. 6 show the relationship between the flow rate M of the oil and the time t when the moving speed of the piston 3 is decelerated. The curve b" shows the case where the initial opening of the throttle device 16 is substantially zero while the curve b' the case where the initial opening of the throttle device 16 is about maximum,

As may be apparent from the foregoing, with the embodiment shown in FIGS. 4 and 5 since the initial opening of the throttle device 16 can be changed or adjusted by controlling the throttle valve 30, the practical opening of the former can be selected effectively for the devices to be controlled in position irrespective of the initial opening of the throttle device 16.

It will be apparent that many modifications can be formed without departing from the concept of the novel concept of this invention.

Claims

We claim as our invention:

1. An acceleration and deceleration valve apparatus, comprising in combination:

a. a housing body (1a) having a bore (4) therein with a piston (3) in said bore, said piston dividing said bore into fromt (10) and back (7) chambers, bias means (2) operatively connected for biasing said piston (3), an oil chamber (8) juxtapositioned with said back chamber;

b. a tapered projection (5) on said piston extending into said back chamber and adapted to longitudinally enter said oil chamber (8);

c. a groove (15) in said oil chamber (8) towards said back chamber (7), said tapered projection and groove (15) being so disposed that the size of the groove opening is controlled by the longitudinal position of said tapered projection (5) so as to form a throttle (16) and an oil passage (17) from said groove;

d. an oil pressure supply source (19), throttle means (12) between said oil pressure supply source and said front chamber (10); and,

e. a by-pass line (14a, 14b) having a control valve (14) therein connected between said pressure supply source (19) and said oil chamber (8) whereby when the control valve (14) is closed, oil supplied from the pressure supply source (19) flows into the front chamber (10) to shift the piston (3) towards the back chamber (7) against the bias means (2) so that the projection (5) is also shifted, substantially closing the throttle (16) and, when the control valve (14) is opened, oil flows to the oil chamber (8) through control valve (14) through the throttle (16) and into the oil passage (17), the piston (3) is moved towards the front chamber (10) by the bias means (2).

2. A valve apparatus as claimed in claim 1 where said bias means (2) are coiled spring means disposed coaxially with said piston (3) coupled thereto.

3. An apparatus as claimed in claim 1 wherein said bore and said oil chamber are cylindrical and coaxial.

4. An apparatus as claimed in claim 1 wherein said bias means (2) are first and second spring biased check valves (21, 22) respectively coupled to said front and back chambers.

5. An apparatus as claimed in claim 1 including a second throttle operatively coupled to said first throttle.

6. An apparatus as claimed in claim 5 wherein said second throttle is a needle valve.

7. An acceleration and deceleration valve apparatus comprising a housing body (1a) having a bore (4) therein, a piston (3) in said bore with bias means (2) for biasing said piston, a throttle (16) with an opening which is controlled by said piston (3), said piston (3) dividing said bore into front (10) and back (7) chambers, an oil passage (14a, 14b) connecting said two chambers, a control valve (14) provided in said oil passage (14a, 14b), a pressure source (19) for supplying oil to said oil passage and through said throttle (16) said bore (4) and said throttle (16) being disposed in series, whereby when said valve is opened said bias means (2) operates to move said piston to one direction to gradually open said throttle with the movement of said piston, while when said valve is closed said piston is moved to the other direction by the amount of oil flowed into said valve to gradually close said throttle with the movement of said piston.

8. A valve apparatus as claimed in claim 7 where said bias means (2) are coiled spring means disposed coaxially with said piston (3) coupled thereto.

9. An apparatus as claimed in claim 7 wherein said bore and said coil chamber are cylindrical and coaxial.

10. An apparatus as claimed in claim 7 wherein said bias means (2) are first and second spring biased check valves (21, 22) respectively coupled to said front and back chambers.

11. An apparatus as claimed in claim 7 including a second throttle operatively coupled to said first throttle.

12. An apparatus as claimed in claim 11 wherein said second throttle is a needle valve.