DE1936370A1 - Valve unit for controlling double-acting working cylinders - Google Patents

Description

VOLKSWAGEKWEHK Aktiengesellschaft 1936370

518 Wolfsburg the Η. July 1969

Our reference: K 804
1728-Al / Bu

description

Valve unit for controlling double -acting working cylinders

The invention relates to valves with a 5-way 3-position slide for controlling double-acting working cylinders with pneumatic or hydraulic drive, the pistons of which move quickly when an appropriate protective device is actuated should be stopped and held in this stop position »

It is known to use valves with 5-way 3-position spool To use control of double-acting working cylinders » The middle position of the slide is locked of the working piston used. In a known execution, both sides of the piston are in this middle position with the full network pressure applied, resulting in a satisfactory stop and a stability of the position cannot be achieved because of external weights and different piston surfaces resulting forces are not compensated. In another version are in the middle stop position of the slide, all channels of the valve are closed. Although this valve shows good stopping behavior even with larger masses, because a one-sided increase in brake pressure is possible. However, the resulting springback is undesirable. In addition, one-sided weight loading or different piston areas and leaks in the lines can result or the stop position in the piston cannot be maintained. The main disadvantage of this valve, however, is that the After a longer stop position, continue driving the amount of air necessary for the exhaust air throttles and end position damping to work has escaped through leaks, which results in an unintentionally rapid movement.

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Another disadvantage of the previous valves with 5-way 3-position spool is that in an emergency stop the cylinder one System are no longer able to absorb external forces and may leave their end position already reached.

The invention is based on the object of building a valve with which is necessary for the stable stop position of the working piston Pressures in the cylinder sides can be set according to the respective load and piston area ratios can ensure that the required equilibrium condition is met and is retained even in the event of leaks. In addition, the Piston be able to absorb external forces in its end positions.

In the following 2 valves are described, which are in the task meet the requirements mentioned. The valve 1 in FIG. 1 is acted upon the cylinder sides in the stop position with the necessary equilibrium pressures. The valve 2 in Fig. 2 provides a unilateral pressurization in the end positions of the working piston, whereby the piston can absorb external forces. The functioning of both valves is independent of one another. Therefore you can easily combine both valves in one valve.

The structure of the valve is explained with reference to Fig. 1:

The piston 2 of the cylinder 1 is loaded with the weight 3 » via the connection plate 6 from the slide which is movable in the housing 9 10 controlled. The upward movement (direction A) takes place by actuating the left solenoid valve 19 »by pressing in channel 17 into the left pilot control room by moving the slide 10 to the right (Direction A) against spring 14 and stop 16, the space A the receives full setting pressure and room B via duct S and the exhaust air throttle 8 is relieved. The downward movement takes place in the same way, but in the opposite sense through solenoid valve 20,

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Pressure on channel 18 and the right pilot control chamber, slide 10 to the left (direction B) against spring 13 and stop 15 » whereby pressure is applied to side B and side A is relieved via channel R and exhaust air throttle 7. In the event of a stop, none of the solenoid valves 19 and 20 is excited, the channels 17 and 18 are relieved and the springs 13 and 14 bring the slide into the center position shown.

According to the invention, the additional channels are new on this slide A1 and A2, as well as B1 and B2, which are only connected to one another in the middle position by the slide recesses 11 and 12, respectively However, working positions are locked.

Another new feature is an additional pressure control unit 21, which contains four pressure relief valves. The left pressure relief valve, which is designed with a good braking effect on the full nominal width, which consists of valve disk 25, spring. 27, spring plate 29 and adjusting screw 31, ensures a rapid build-up of brake pressure in space A2 up to a value that can be set by 31, which acts on cylinder side A via A2, A1 and channel 23 in the middle position. When the spring 27 is relaxed, as shown,

the full network pressure (e.g. 5 kp / cm) is effective. The in part 31 built-in, consisting of ball 33 »spring 35 and adjusting screw 37 and the pressure relief valve designed with a smaller nominal diameter has the task of a slightly higher setting (e.g. 5 »5 kp / cm) to reduce any short-term pressure increases that may arise during braking so that within a predetermined time (approx. 1 to 3 seconds) after the stop time the set pressure in A1, A2 and A is achieved and maintained, even if there are leaks. The two overpressure valves arranged on the right with parts 26, 28, 30, 32, 34, 36 and 38 have the same effect on channel B2, i.e. in the middle position of the spool also on cylinder side B. Weg the weight load 3 must be met to meet the stability condition in the stop position, the pressure in B by tensioning the spring 28 and releasing the spring 36 accordingly

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be reduced (ζ. B. 2.5 kp / cm), with the small pressure relief valve must also be set a little higher than the nominal pressure (ζ. B. 3 »0 kp / cm). The large pressure relief valve is closed, when the corresponding equilibrium pressure has built up in B. The small pressure relief valve has the task of following the previous Downward movement of the existing full network pressure after a certain time (1-3 seconds) after the stop has been pressed to the target pressure (e.g. 3fO kp / cm).

With the slide valve described, it is possible for everyone Stop cylinder pistons with constant weight load or unequal piston areas quickly and in the position they have reached, to be able to hold as long as desired even in the event of leaks in the piston, the rod seal or in the lines, whereby for the When restarting, there is enough air available for the exhaust air throttles to work effectively.

If the weight influence is not constant (crank or knee lever movements) it is also possible to meet the equilibrium condition for each cylinder position if the pressure relief valves are stroke-dependent using curves or similar means adjusted.

The valve 2 is explained below according to FIG.

The piston 2 of the cylinder 1 is loaded with the weight 31 via the connection plate 6 of the movable in the valve housing 9 Slide 10 controlled, with the piston 2 braked in the drawn center position and held with a tight system will. Neither of the two limit switches 4 (position B) and 5 (position A) is activated.

For the downward movement in direction B, the slide 10 must assume the left end position, the channels P with B and A with S are connected and the exhaust throttle 7 determines the speed. In the piston end position B, the end position indicator is switched 4 actuated.

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In the same way, but reversed, the upward movement in direction A is caused by the right end position of the slide 10 triggered, where there is a connection from P to A and B to S with speed adjustment by exhaust air throttle 8. In the Piston end position A, the end position signaling switch 5 is actuated. At or in the ends of the slide 10 are the two, from the parts 11, 15, 15 and 17 for the left side and from the parts 12, 14, 16 and 18 for the right side existing additional Arranged pilot piston. You have them in well-known slide designs Task performed by 2 springs, the slide 10 by pressure on the pilot control chambers 25 and 25 as well as 24 and 26 in to bring the middle position. Pressure in rooms 24 and 26 and relief in rooms 25 and 25 is in the left slide position B, reversed pressure on 25 and 25 and relief on 24 and 26 the right slide position A, whereby the sizes of the control surfaces are intentionally designed so that the surfaces F (D) are more than twice as large as the surfaces f (d), so that for the movement in the middle position one of the surfaces F (D) - f (d) corresponding greater force is available as for the force causing the end positions, which corresponds to the areas f (d). By this measure, the security for reaching the middle position is significantly increased, because a stiff or to The valve with a tendency to seize no longer reaches the end position with the lower force (malfunction with the need to change the valve), However, it is to be assumed that the central position for stopping the piston is still safely reached with the greater force will.

Another important property of the thus formed slide is that it if all Ansteuerräume 25, 25, 24 and 26 are pressureless its respective end position reached by the friction of the seals 15t ¹ 5, 14 and 16 maintains. This property is used for end position stabilization.

To explain the function of the pilot control unit 64 and the solenoid valves 54, 55, 56 and 57, the drawn state went out.

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-6- 1336

The pilot pressure comes from channel P via channel 51, the recess in seal 35 »over filter 33» channel 36, over the one in the left Position standing storage valve 46 in the channel 43 and from there via the non-actuated pilot valves 37 and 38 and via the Channels 29 and 30 in the pilot control rooms 23 and 25 or 24 and 26, whereby the middle position of the slide is reached and the working piston 2 is stopped. There is also pressure under the two solenoid valves 54 and 55 · All other channels are depressurized.

If the working piston is now to move in direction A, is activated by manual or automatic actuation of the button 60 the solenoid valve 55 is energized, whereby pressure is applied to the initially still blocked solenoid valve 57 and in the channel 48 »as well as via the Throttle 40 enters the channel 27, which at its end by the middle position stop, which also acts as a valve disk 17 is closed so that on the control piston of the pilot valve 38 the pressure can build up and the left one at that Switch position assumes. This means that channel 30 and the pre-control rooms become 24 and 26 relieved, so that the slide 10 and piston 12 due to the pressure on the left in space 2.5 to the right is shifted in direction A against the stop 20, whereby the piston movement 2 in direction A takes place. Interrupting push button 60 results in the initial state again. By briefly manual tapping, the piston 2 can thus with short partial movements be moved slowly to any position.

If the piston 2 is in its end position when the solenoid valve 55 is energized A has reached and actuated the limit switch 5 and so that the solenoid valve 57 is energized, channel 52 receives the right side of the OR element 50 pressure, whereby channel 51 is blocked will. Via channel 4? becomes the left large piston of the accumulator valve 46 applied and pushed this to the right, although also on the right smaller piston surface via the or-member 44 and channel 45 pressure is pending. In this position, channel 43 »channel 29 and the left pilot control chambers 23 and -. 25 relieved, so that the slide end position A and thus the pressure remains in room A. After the pressure has been reduced, the

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Button 6θ or the plug 61 or the emergency switch 62 or the Main switch 63 are interrupted by the solenoid valve 55, partly also the solenoid valve 57, the channels 48, 27, 45, 52 and 49 and thus both sides of the storage valve 46 be relieved, but this does not change its position. The right end position of the slide 10 is therefore retained. That subsequent switching back of the valve 38 also remains without effect.

The piston 2, which is under pressure in the end position A, is therefore now able to absorb external forces.

The movement of the working piston 2 in the opposite direction B is by pressing the button 59 and energizing the solenoid valve 54 initiated. The pressure in channel 47 "made possible by the throttle 39 and the blocked check valve 41" has an effect first via the OR element 44 blocking the channel 48 and the channel 45 onto the right small piston area of the accumulator valve 46 off. Since the larger left piston area is depressurized (55 and 56 not excited), it takes up the left position again and the channel 43 receives pressure, which is also via the non-actuated valve 38 and the channel 30 in the right pilot control chambers 24 and 26 arrives. The left valve 37 is initially not yet switched because the channel 28 is still connected to the relief channel 22 connected is. Above 37 and 29, rooms 23 are also given and 25 pressure. The piston 12 with the stop 18 and the slide 10 therefore briefly assume the middle position. Only when the channel 28 passes through the valve, which also acts as a valve seal Stop 18 is closed and pressure is built up, the valve 37 can switch, relieve the channel 29 and the spaces 23 and 25, whereby the slide 10 moves to the left because of the pressure in the space 26 and causes the piston movement 2 in direction B. The resulting opening of the limit switch 5 and falling off of the solenoid valve 57 remains ineffective. There is now a stop again at each point of the stroke by opening 59, 61, 62 or 63 and a "tap" with button 59 is possible.

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Only the end position switch 4 closing in end position B is effected the right position again via the solenoid valve 56 and the OR element 50 of the storage valve 46 »whereby the slide 10 as a result bilateral relief maintains its position B and the pressure in channel B with simultaneous relief of the piston side A also stabilizes the piston 2 against external forces in this end position. The countermovement can then only be started again by pushbutton 60 and solenoid valve 55 »via the switching back of the accumulator valve 461 slide center position, switching of the valve 58 and triggered by moving the slide 10 to the right. This initially seems to be a time-consuming process « ^ You have it, however, by correspondingly large dimensioning of the ■ Valves 57, 58 and 46 as well as channels 51, 56, 45, 29 and 50 in the hand of keeping the time for this process within tolerable limits.

The requirement that the correct functioning of all moving parts must be a prerequisite for normal operational function, is fulfilled with regard to the pilot pistons 11 and 12 required for the middle position by the process described last, that a countermovement can only take place from the piston end position if the center position is previously faultless for a short time was achieved. If further z «B-. Valve 57 does not switch back, the slide position B cannot be left. If it does not switch, position B will not be reached. The same applies to valve 58 with effect on position A.

If the storage valve 46 is not activated after activation of 54 or 55 switches back to the left position, the slide 10 can no longer change its position because the control pressure is missing and a Piston movement is no longer possible. If it does not switch to the right in the piston end position, then the activation is interrupted the harmless middle position and when external force acts on the piston 2, this becomes its end position and thus leave its end position signaling switch 4 or 5. This also leads to a harmless malfunction. If the solenoid valve is in the stabilized cylinder end position B. 54 does not switch back, is a steering in the opposite direction A.

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no longer possible because the large left side of the accumulator valve 46 still over 56 »51» 50 and 49 is under pressure and this can't switch back. The same applies accordingly to the solenoid valve 55

If the solenoid valve 56 or the limit switch 4 no longer switches back, the movement in direction A and stabilization in the end position A is possible, the accumulator valve 46 having assumed its right-hand position. When the button 59 and solenoid valve 54 are next activated, however, the accumulator valve 46 also receives pressure on the large left control surface, so that it cannot switch to the left and a slide movement 10 is no longer possible. The same applies mutatis mutandis to the solenoid valve 57 ¹ HiId the limit switch 5 · The valve can therefore be addressed as "intrinsically safe" due to the properties mentioned.

About impurities in the pilot control medium, which the function of the storage valve, which is mainly designed as a sealless slide 46 can disturb, to keep away is a replaceable one Filter 33 is provided.

By turning the seal 35 mn 180 it is also possible to to be able to supply the pilot control medium to the connection 34 of the plate 32 externally when the main slide 10 is at higher pressure should be operated.

When using the valve in purely pneumatic or hydraulic The solenoid valves 54 and 55 can be dispensed with. The control then takes place directly on channels 47 and 48. The solenoid valves 56 and 57 must then be operated pneumatically or hydraulically controllable valves are replaced, which are then operated by end position signaling valves. The function is otherwise the same.

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If the solenoid valves 54 or 55 do not switch on, occurs no control. If solenoid valve 56 or 57 does not switch on, the same harmless effect is present as if - as already described - the storage valve 46 is moving to the right is prevented.

Thus the requirement is that the proper function of all moving parts is a prerequisite for normal operation and in the event of malfunctions a piston stroke is no longer possible or the Stopping case occurs, fulfilled.

The valve must therefore be changed for further undisturbed operation. In addition, this valve is still used the correct functioning of the limit switch 4 and 5 controlled in each work cycle because of a movement out a bonded position can only take place if the end position signaling switch of the other end position is not actuated. An otherwise necessary electrical control is not feasible.

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Claims (14)

VOLKSWAGENWERK Aktiengesellschaft 1936370 Wolfsburg Mg 14 July I969 Our reference: K 80 &
1728-Al / Bu Expectations ".. valve unit (Fig. 1) with a 5-way 3-position slide '(1O) for controlling double-acting working cylinders with pneumatic or hydraulic drive, characterized in that the two sides of the working piston (2) are in the middle position of the control spool (1O) via two pressure relief valves (25, 27, 28, 31; 35, 55, 57 or 26, 28, 50, 52; 54, 56, 58) and channels (A2, A1, A or B2, B1, B), which in this slide position are related to each other, with the corresponding Equilibrium pressure are applied. 2. Valve unit according to claim 1, characterized in that the springs (27 and 28) of the two pressure relief valves with the help of Adjusting screws (51 or 52) are pretensioned so that the pressure relief valves are each set up according to the desired Close equilibrium pressure in the working cylinder. 3. Valve unit according to claim 1, characterized in that the setting of the pressure relief valves (25, 27, 31 or 26, 28, 32 and 35, 55, 37 or 34, 36, 38) is varied by curves or similar means depending on the piston stroke, 4. Valve unit according to claim 1, characterized in that the pressure relief valves consisting of the parts (35, 35, 57 or 54, 56, 58) by pretensioning the springs (55 or 36) and the appropriate size of the respective pressure relief valve one that occurs when the working piston (2) is braked Reduce the pressure increase within a predetermined time after the stop time. 009886/0928 5. Valve unit (Fig. 2) with a 5-way 3-position slide (1O) for controlling double-acting working cylinders pneumatic or hydraulic drive, characterized in that when the solenoid valves (54 » 55 »56, 57) an immediate stop of the working piston and in the end position A or B of this piston to remain in this position under full pressure with the help the pilot control unit (64) and the 5-way 3-position spool (1O) is caused. 6. Valve unit according to claim 5 »characterized in that on One pilot piston (11 or 12) with the seals (13 »15 or I4, 16) and the stops (17 or 18) is attached. 7. Valve unit according to claim 5 »characterized in that the control surface F of the pilot piston (11 or 12) more than is designed to be twice as large as the area f. 8. Valve unit according to claim 5 »characterized in that at non-activated solenoid valves (54, 55, 56, 57) the pilot control chambers (23, 25) or (24, 26) via channel (3I), filter (33), Channel (36), accumulator valve (46), channel (43), pilot valves (37 or 38) and channels (29 or 30) are pressurized ) . 9. Valve unit according to claim 5, characterized in that by Control of the pilot valves (37 or 38) the connection the pressure line P with the pilot control chambers (23, 25 or 24 »26) is interrupted and these are relieved. 10. Valve unit according to claim 5 »characterized in that the 5-way - 3 position slide by actuation of the end position switch (5 or 4)» which via solenoid valves (57 or 56), OR element (50), accumulator valve (46) , which has two different piston surfaces, channel (43), channel (29 or 30) relieve the pilot control chambers (23, 25 and 24, 26), with the help of the seals' (13, 15 or 14 »16) in its end position ^is held * 009886/0928 11. Valve unit according to claim 5 »characterized in that a movement of the slide (10) in the working position A or B only through the corresponding protective locks behind horizontal activation of the solenoid valves (55 or 54) can take place, but not by the sole actuation of the End position signaling switch (5 or 4) and the solenoid valves (57 or 56). 12. Tentileinheit according to claim 5, characterized in that the individual puncture elements of this valve are arranged in such a way that in the event of malfunctions of the slide (1O) its no longer leaves the assumed position or moves into the middle position. 15. Valve unit according to claim 5 »characterized in that the control medium is either removed from the heating duct P either and via channel (31), seal (35) »filter (33), channel (36) is supplied or via connection (34) »recess of the seal (35) rotated by 180 ° and filter (33) enters the pilot control channel (36), the channel (3I) being shut off will. 14. Valve unit according to claim 1 and 5 »characterized in that the two independent valve units in their mode of operation be combined in one valve unit. 009886/0928