GB2059020A - An air-pressure regulating apparatus - Google Patents

Abstract

An air-pressure regulating apparatus suitable for regulating the pressure of air supplied to a piston- type of air-balancer has a hollow body 1 divided into two chambers 1a and 1b by a diaphragm 2, chamber 1a being vented to atmosphere and chamber 1b having an outlet port 4, an inlet valve 5 communicating with an inlet port 3, and a pressure relieving valve 7. A first compression spring 12 mounted between discs 10a and 10b serves to urge the diaphragm 2 towards the chamber 1b, the spring force being adjustable by means of screw-threaded adjuster 11. A cylindrical cam 15 can be operated manually to hold the disc 10a at a position where the inlet valve 5 remains open and the pressure relieving valve remains closed, or at another position where the inlet valve 5 remains closed and the pressure relieving valve remains open. In the illustrated position of the cam 15, the disc 10a is free to move over a limited range, thereby allowing pressure regulation to take place. A second adjustable spring 20 also biasses the diaphragm, irrespective of the action of the cam 15 on the disc 10a. <IMAGE>

Description

SPECIFICATION An air-pressure regulating apparatus This invention relates to an air-pressure regulating apparatus, suitable in particular (but not exclusively) for use with an air-balancer of the type in which an article, while being suspended by an air-cylinder, is maintained at a given position by a lifting force equal to the weight of the article, so that the article may easily be freely handled by an operator, despite the weight of the article.

Air-balancers are known and have been described for example in our Japanese Patent Specifications Nos. 791224 and 810332.

The balancers there described allow an article not only to be freely moved up or down whilst being suspended in a balanced state, but also may be raised or lowered, in the manner of a hoist upon operaton of a handle. However, a piston valve is used in these known arrangements, which valve has portions subjected to friction and which therefore are lubricated by an oiler. This known arrangement thus suffers from some disadvantages: oil contamination can occur as oil issues through the exhaust port, valve trouble may occur due to oil shortage, and frequent overhaul of the valve is required.

It is an object of this invention to provide an air pressure regulator suitable for an airbalancer, which apparatus does not suffer from the just-mentioned probiems when used in conjunction with an air-balancer.

Accordingly this invention provides an airpressure regulating apparatus comprising a hollow body, a diaphragm mounted within the body to divide the interior thereof into two chambers one of which is vented to the atmosphere and the other of which is provided with an outlet port for pressure-regulated air, the other chamber also being provided with air inlet and pressure relief valves which are alternatively opened in response to movement of the diaphragm, a compression spring mounted between a pair of abutments, one of which is adjustably disposed with respect to the body and the other of which is connected to the diaphragm to exert a force thereon tending to move the diaphragm into the other chamber thereby closing the pressure relief valve and opening the air inlet valve, and a manual control to effect movement of the other abutment allowing the air-pressure in the other chamber to be regulated by the diaphragm or to be above or below the regulated pressure.

Preferably the manual control has a first position in which said other abutment is moved away from the diaphragm thereby relieving the regulated pressure, a second position in which said other abutment is moved forwards the diaphragm thereby opening the air inlet valve to the other chamber, and a third position in which said other abutment is free to move with the diaphragm in response to air-pressure in the other chamber. The manual control may be provided with a stop arrangement, whereby the control will remain set to the first position, thereby providing an 'off' state for the apparatus.

A second compression may be provided to urge the diaphragm towards the other chamber, which second spring acts on the diaphragm irrespective of the setting of the manual control. This arrangement has the advantage of allowing the weight of a hook or other attachment to an air-balancer to be compensated for, when the air-pressure regulating apparatus is used in conjunction with a piston type of balancer.

The invention extends to the combination of an air-pressure regulating apparatus and an air-balancer of the piston type, arranged such that the apparatus directly or indirectly (for instance via a relay valve) controls the supply of air under pressue to the balancer, from a source of compressed air.

The advantage offered by the air-pressure regulating apparatus of this invention is mainly that the apparatus needs no lubrication with the result that it is free from conventional oil contamination problems, valve trouble due to oil shortage and does not require frequent overhauls. An air-balancer provided with the apparatus can be controlled easily for balancing, lifting, lowering and off states, by operation of a single handle of the manual control.

By way of illustration only, three specific embodiments of air-pressure regulating apparatus of this invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is a longitudinal sectonal view of a first embodiment of air-pressure regulating apparatus constructed in accordance with this invention, for use with a relatively small size air-balancer; Figure 2 is a plan view of a cam mounted in the apparatus of Fig. 1; Figure 3 is a view similar to part of Fig. 1 but of a portion of a second embodiment of this invention, for use with a medium size airbalancer; and Figure 4 is a diagrammatic view of a third embodiment of the apparatus being used with a relatively large size air-balancer, with the intervention of a booster relay.

As can be seen from Fig. 1, the air-pressure regulating apparatus comprises a body 1 divided into an atmospheric chamber 1a and a pressure chamber 1 b by a diaphragm 2, the atmospheric chamber 1 a being open to the atmosphere. The body 1 defines an inlet port 3 communicating with the pressure chamber 1 b through an inlet valve 5, which port 3 is for connection to a compressed air source (not shown) and an outlet port 4 communicating directly with the chamber 1 b, for connection to an air-balancer (such as shown in Fig. 4).

The inlet valve 5 is fixed to a common shaft 6, on which a relief valve 7 is also fixedly mounted. The relief valve 7 co-operates with a central bore in the diaphragm 2 in the pressure chamber 1 b, to relieve excess air-pressure. The atmospheric side of the diaphragm 2 is urged by one end of a rod 8, which extends from the body 1 into a cylinder 9.

The cylinder is secured to the body 1 and contains a pair of discs 1 Oa and 1 Ob, a compression coil spring 1 2 being interposed between the discs. The other end of the rod 8 is received in the front disc 1 Oa, so as to be biased forwardly by the coil spring 1 2. The resilient force of spring 1 2 can be adjusted by an adjuster bolt 11 threaded in the cylinder 9 so as to engage behind the rear disc 1 Ob. A pair of radial pins 1 3 are fixed to the front disc 1 Oa and project out of the cylinder 9 through a pair of elongate slots 14.

As can be seen in Fig. 2, a cylindrical cam 1 5 is rotatably mounted on the cylinder 9 and is formed with cam slots into which the pins 1 3 fit. The cam slots each have up, down and off cam-planes 16, 17 and 18. A handle 19 is attached to the cylindrical cam 1 5 so as to allow rotation thereof, to cause the pins 1 3 to engage one of the cam-planes.

In operation, the handle 1 9 is free (as shown in Fig. 2) and the adjuster bolt 11 is gradually threaded in, after an article has been attached to the balancer receiving air under pressure from the pressure regulating apparatus. Initially, the rod 8 presses the diaphragm 2 toward the pressure chamber 1 b to close the relief valve 7 and open the inlet valve 5. Then, compressed air enters the pressure chamber 1 b to press the diaphragm 2 back against the rod 8 and close the inlet valve 5. When the valve 5 is closed again, the diaphragm 2 lies at a position in which the forces of both the air-pressure in the pressure chamber 1 b and the coil spring 12 are in a state of balance. Thus, the balancer also is in the balancing state, in which the article is freely suspended by a force equal to its weight.In this balancing state, should the article be lifted by an operator, the air-pressure both in the balancer and thus also in the pressure chamber 1 b is slightly reduced to allow the diaphragm 2 to move toward the pressure chamber 1 b and open the inlet valve 5. Then, compressed air enters the balancer through the pressure chamber 1 b to assist the lifting. Thus, the operator can lift the article by exerting only a light force. On the other hand, when the article is pulled lower, the airpressure slightly increases, thus moving the diaphragm 2 against the resilient force of the coil spring 12, thereby opening the relief valve 7. This relieves the air-pressure in the balancer, with the result that the article can be lowered by exerting only a light force.

When the handle 1 9 is operated to fit the pin 1 3 on the up cam-plane 16, the rod 8 together with the disc 1 Oa are advanced to open the inlet valve 5 and hence to let compressed air through chamber 1 b into the balancer. Thus, the balancer is in the lifting state, and the article is rapidly lifted.

When the handle is operated to fit the pin 1 3 on the down cam-plane 17, the rod 8 together with the disc 1 Oa are retracted to open the relief valve 7 and relieve the airpressure from the balancer. Thus, the balancer is in the lowering state, and the article is steadily lowered. When the handle is released from the up and down planes 16, 17, the balancer always remains in the balancing state.

When the handle is operated to fit the pin 1 3 into the recess defined by the off camplane 18, the relief valve 7 always remains open and the balancer is in the off state, so that the article can be removed from the balancer. By virtue of the shape of plane 18, the pin 1 3 remains fitted in the recess defined thereby, even when the handle 1 9 is released.

In the case of the balancer supporting a somewhat heavy hook, article or the like, a second compression coil spring 20 can be used. Otherwise, the hook would inconveniently move down to the lowest position when the balancer is in the off state. The second coil spring 20 is mounted in parallel with and beside the aforementioned coil spring 1 2 and drives a lever 21. The lever 21 projects through a slot into the cylinder 9, the end of the lever being bifurcated to straddle the rod 8 and engage a shoulder portion 8a thereof, so that the second coil spring 20 biases the rod 8 toward the pressure chamber 1 b in conjunction with the aforementioned coil spring 12, through the intermediary of the lever 21.The second coil spring 20 is arranged to act to the rod 8 and give a balancing force equal to the weight of the hook when the balancer is in the off state, in which the aforementioned coil spring 1 2 is rendered inactive.

Fig. 3 shows a second embodiment constituting a modification of the apparatus shown in Figs. 1 and 2 so as to be suitable for a medium size air-balancer. The first coil spring 1 2 acts on the rod 8 indirectly, through the intermediary of the lever 21 which also is acted on by the second coil spring 20. The medium size air-balancer needs to be capable of handling a greater air-flow, and thus has a larger diaphragm which is acted on by a greater spring force than the apparatus for a smaller balancer. However, the first coil spring 12 in Fig. 3 is the same as that in Fig. 1, because the force exerted by the spring is increased by leverage of lever 21 acting on the rod 8. The handle of the apparatus in Fig.

3 needs no greater operating force than that of Fig. 1, since the coil spring rates are the same.

When the apparatus is used with a relatively large air-balancer, the apparatus should be provided in a compressed air signal circuit rather than directly to control the air supply to the balancer, for such a balancer would otherwise require regulating apparatus having a very large diaphragm urged by a very strong spring. Even were a lever provided to increase the force of the spring (as in the embodiment of Fig. 3), the spring force may prevent the handle from being manually operated. A large diaphragm is necessary because a large air flow rate is required for a relatively large size air-balancer, and thus the inlet and relief valves must have an enlarged cross-sectional area; the diaphragm must thus have an increased diameter so as to maintain the required area ratio with respect to the valves, to prevent a reduction in sensitivity of the apparatus.

As can be seen in Fig. 4, the apparatus of this invention is connected as a generator for an air pressure signal supplied to a booster relay 22, directly coupled in series with a source of pressurised air and the relatively large size air-balancer 25. Circuit lines, as are shown by broken lines in Fig. 4, connect the inlet and outlet ports 3 and 4 of the body 1 of the apparatus respectively to a compressed air source 26 and the signal port 27 of the booster relay 22, and the inlet and outlet ports 28 and 29 of the booster relay 22 respectively to the compressed air source 26 and the inlet port 30 of the air-balancer 25.

First and second diaphragms 23 and 24 are mounted in the booster relay 22, the second diaphragm 24 being adapted to receive an air pressure signal and act on the first diaphragm 23, as an air spring. In a case where both diaphragms are of the same diameter, the signal and regulating air-pressures are identical and balanced one with the other. The signal pressure generated in the apparatus needs only a small amount of air to flow and only a small diaphragm backed up by a relatively weak spring, so that the handle 1 9 can be operated as easily with a light force as in the case of regulating apparatus for a small size air-balancer. The large size air-balancer 25 shown in Fig. 4 is always provided with a relatively heavy hook 31 together with an attachment 32 to seize an article 33. The weight of the hook and the attachment should be balanced with the aforementioned second spring in the apparatus, when the handle 1 9 is set to the off state.

From the foregoing, it will be understood that the pressure regulating apparatus of the invention as described above can be used in conjunction with air-balancers of all sizes, and allows a good balancing effect as well as permitting the balancer to have a raising and lowering performance, as a hoist. Moreover, the apparatus can be adjusted to compensate for the weight of a hook and any attachment to the balancer, before an article is connected thereto. Operation of the apparatus to control the balancer is easy, quick and reliable, by operating a single handle of the apparatus.

The apparatus is free from oil contamination, seizures and oiling-maintenance, because it has no oiler.

Claims (9)

1. An air-pressure regulating apparatus comprising a hollow body, a diaphragm mounted within the body to divide the interior thereof into two chambers one of which is vented to the atmosphere and the other of which is provided with an outlet port for pressure-regulated air, the other chamber also being provided with air inlet and pressure relief valves which are alternatively opened in response to movement of the diaphragm, a compression spring mounted between a pair of abutments, one of which is adjustably disposed with respect to the body and the other of which is connected to the diaphragm to exert a force thereon tending to move the diaphragm into the other chamber thereby closing the pressure relief valve and opening the air inlet valve, and a manual control to effect movement of the other abutment allowing the air-pressure in the other chamber to be regulated by the diaphragm or to be above or below the regulated pressure.

2. An air pressure regulating apparatus as claimed in claim 1, wherein the manual control has a first position in which said other abutment is moved away from the diaphragm thereby relieving the regulated pressure, a second position in which said other abutment is moved towards the diaphragm thereby opening the air inlet valve to the other chamber, and a third position in which said other abutment is free to move with the diaphragm in response to air-pressure in the other chamber.

3. An air-pressure regulating apparatus as claimed in claim 1 or in claim 2, wherein a rigid rod interconnects said other abutment and the diaphragm, such that the force exerted by the compression spring is transferred through the other abutment and the rod to the diaphragm, thereby to bias the diaphragm towards the other chamber.

4. An air-pressure regulating apparatus as claimed in any of claims 1 to 3, wherein a second compression spring is provided to urge the diaphragm towards the other chamber in conjunction with the first-mentioned compression spring, the second compression spring remaining operative irrespective of the setting of the manual control.

5. An air-pressure regulating apparatus as claimed in claim 4, wherein means are provided to adjust the thrust exerted by the second compression spring.

6. An air-pressure regulating apparatus substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2 or in Fig. 3 of the accompanying drawings.

7. The combination of an air-pressure regulating apparatus as claimed in any of the preceding claims and a piston-type of airbalancer, air under pressure being supplied to the balancer by the air-pressure regulating apparatus from a source of compressed air.

8. The combination of an air-pressure regulating apparatus as claimed in any of the preceding claims, a piston-type of air-balancer and a pressure-controlling relay valve, the airpressure regulating apparatus regulating the signal air-pressure supplied to the relay valve and the relay valve controlling the supply of air under pressure to the balance from a source of compressed air, depending upon the signal air-pressure.

9. The combination of claim 8 substantially as hereinbefore described with reference to and as illustrated in Fig. 4 of the accompanying drawings.