US3185237A - Hydraulic rams - Google Patents

Description

May 25, 1965 J. BUTTERWORTH HYDRAULIC RAMS I 3 Sheets-Sheet 1 Filed Dec. 6. 1961 M y 1965 A. .J. BUTTERWORTH 3,185,237

' HYDRAULIC RAMS Filed Dec. 6. 1961 3 Sheets-Sheet 2 Awe/woe Amman/.0 dmuss Burrnwaxr BY M f-CJM May 25, 1965 J. BUTTERWORTH 3,185,237

HYDRAULIC RAMS Filed Dec. 6, 1961 3 Sheets-Sheet I5 A ken/04w Jnuss .BUTTEKWORTH United States Patent 3,185,237 HYDRAULIC RAMS Archibald .lames Butterworth, 7 Grove Gardens, Frimley, England Filed Dec. 6, 1961, Ser. No. 157,429 Claims priority, application Great Britain, Dec. 7, 1960, 42,051/69; Dec. 6, 1961, 43,781/61 1 Claim. (Cl. 180-1) This invention relates to hydraulic rams of either the single or double acting type. For certain purposes it is advantageous to be able to extend the ram rapidly under no load or light load conditions whereafter extension under load may be less rapid.

Such conditions apply where a hydraulic ram is employed on a motor vehicle to lower rollers into engagement with the ground to raise the vehicle wheels at one end of the vehicle from the ground which rollers engage the raised wheels and may be driven by them and the rollers are arranged to roll along the ground in such a direction as to swing the end of the vehicle sideways. In such an arrangement the rams are supplied with hydraulic fiuid through a control valve from a pump driven by the vehicle engine and it is advantageous to lower the rollers into engagement with the ground as quickly as possible.

According to this invention there is provided a hydraulic transfer for connection between a source of fluid pressure and a hydraulic ram which transfer comprises a compound piston and cylinder, the smaller area piston and cylinder being arranged to communicate with an inlet for connection with the source of fluid pressure and the larger area piston and cylinder being arranged to communicate with an outlet for connection with the ram and valve means operated by the movement of the compound piston at one end of the stroke arranged to place the inlet and outlets in direct communication with one another, and cut off the communication between the larger area piston and the outlet.

The movement of the compound piston under t e ac tion of the hydraulic pressure may be against the action of a spring and said valve means may be arranged to produce sufficient back pressure that when the inlet and outlet are in direct communication the hydraulic pres sure on the smaller piston is sutficient to counter the force of the spring.

The two sides of the smaller part of the piston may be by-passed by a passage which at one end communicates through valve parts with said outlet and the other end communicates through a non return valve with said inlet.

The by-pass passage may comprise a pipe which extends in a fluid tight manner through a wall of the smaller area piston and is connected at one end to said outlet and is provided with valve parts which are partly covered by said wall at one limit of movement of the com-. pound piston and which pipe at the other end is pro-- vided with said non return valve one side of which is in permanent communication with said inlet.

There may be provided in combination with a hydraulic transformer as set out above a motor driven pump connected through valve means with a reservoir and with the inlet of the transformer and a hydraulic ram connected with the outlet of the transformer.

The valve means may be under joint control of a manipulating member, means controlling the speed of ratus embodying the combination as set out above two hydraulic rams are connetcted to the outlet of the hydraulic transformer and each in extending brings a roller into engagement with the road and raises an adjacent vehicle wheel from the road and at the same time engages that vehicle wheel whereby the roller may be driven by said wheel and rolls along the road in such a direction as to swing the end of the vehicle sideways.

The ram assemblage at its upper end may be articulately connected to a spring part of the vehicle whereas the lower end on which the roller is mounted is connected by a link to an upsprung part of the vehicle so that extension of the ram results in the roller being swung downwardly and sideways.

Other features are set out in the following description and claims which description indicates how the invention is applied to a vehicle parking mechanism reference being made to the accompanying drawings in which:

FIGURE 1 is a view of a part of the back axle of a vehicle looking from the front thereof and showing diagrammatically the hydraulic transformer, the associated gram-p, control valve and one hydraulic ram in the extended condition and the roller for engagement with the ground and with the vehicle wheel, on one side only of the vehicle, the other side of course being the mirror image of the illustrated side;

FIGURE 2 is a similar view to FIGURE 1 and showing the ram in its contracted condition and omitting the transformer;

FIGURE 3 is a section through the hydraulic transformer;

FIGURE 4 is an outside view of the transformer;

FIGURE 5 is a view looking from the left of FIGURE 4 and FIGURE 6 is a side view of an arrangement for interlinking the control valve for the rams with the throttle valve for the vehicle engine.

Referring to FIGURES'I and 2 a rarnl is surrounded by a protective bellows 2 or cover which may. be of synthetic rubber and which may also enclose or incorporate a tension spring 3. The lower element 4 of the ram 1 is rigidly attached to a roller mounting 5 which may be a high duty iron casting. The mounting 5 carries a roller 6 in bearings not shown in this view. A horizontal fore and aft extending pivot pin 15 passing through a part of the mounting 5 secures it to the lower end of a link 7. The upper end of this link is similarly pivoted at 11 on a stationary portion of rear wheel mounting 8. The-vehicle shown has independent suspension by mean of a lower wish bone 9 and transverse leaf spring 10 in a known manner. In this case the upper link pivot 11 has been formed as an extension of the wish bone pivot for convenience, but this pivot 11 may be located elsewhere if preferred.

A hydraulic pipe 12 is connected between the ram 1 and the outlet 22 of a hydraulic transformer 16, 19 (described later) and another pipe 168 connects the inlet 25 of the hydraulic transformer through a valve indicated generally at 166 either to the outlet of a pump-165 driven from the engine of the vehicle or to a fluid storage vessel 169. The valve is arranged to be under the joint, control of a manipulating shaft 167, the pressure of the fluid I, within the valve casingand an electrical device 17% conthe motor which drive the pump and of the hydraulic pressure generated by the pump as set out in US. Patent application Serial No. 801,254, filed March 23, 1959, now Patent No. 3,128,839.

In applying the invention to a vehicle-parking appa Y 14 to the sprung portion of the vehicles chassis frame or body, that is to say, it does not move relative to the main structure when the wheels rise and fall under the influence of road irregularities. tion in the retracted position. It will be seen that the link 7 now lies in a substantially horizontal position, and that when the wheel and hub assembly rise and fall due to the action of the road upon the vehicles springs this link will idle like a normal suspension link without appreciably disturbing the position of the ram and roller as sembly to which it is attached. 7

When the driver actuates the control valve 166 hydraulic fiuid under pressure will be delivered through pipe 12 to ram 1 causing it to extend. As the pivot pin 15 is located below the centre-line joining the upper ram pivot and the upper link pivot 11 extension of the ram will cause the roller assembly to be lowered until it touches the road.

As the height of the upper ram pivot 14 can vary vertically with relation to the road surface and therefore to the final position of roller 6 owing to movement of the springs in accordance with the degree of loading of the vehicle the actual extension required in this ram may vary under differing conditions. For this reason it is desirable to provide sufiicient travel in the ram to enable it to engage fully with the tire under the conditions of lightest load, bearing in mind the fact that the extensive force of the ram will also react on pivot 14 in such a way as to raise the chassis and body of the vehicle an additional dis- 7 tance from the road.

Any convenient arrangement of spring means in place of or in addition to said spring 3 may be used to withdraw the roller 6 from its operating position and bring the equipment to the fully retracted position shown in FIG- URE 2. Alternatively, a double-acting ram system may be used so that retraction as well as extension is performed hydraulically.

Where a conventional twostage single-acting ram is V employed, as in FIGURES 1 and 2, that part of the operating cycle whichlowers the roller assembly from its retracted position to its first contact with the road will necessarily be performed by the larger of two concentric ram cylinders since the larger piston area of this ram stage will cause it to extend first. This situation has two disadvantages and it is an object of the present invention to overcome these. In the first place, a great deal of hydraulic liquid must be displaced to fill the larger ram cylinder, and if the fiuid pump is to be of reasonable size FIGURE 2 shows this construe fluid sufiicient to fill the large diameter upper cylinder cf a conventional two-stage ram. In this way the lost motion involved in bringing the rollers 6 (FIGURES ;1 and 2) down to a point near the road surface is carried out rapidly, and owing to the effort required to displace this volume of hydraulic liquid by pressure acting against a small operating piston there is an immediate rise of pressure at the control valve, so that the control knob will immediately be retained in the out or operating position during this part of the cycle.

In FIGURE 3 a tubular cylinder 16 is retained between end- plates 17 and 18, a tube 19 being permanently attached to the latter. The end plate 17 is provided with an air vent 17a. Tube 19 has formed at its end a disc 20 which carries a tube 21 ending in a suitable screwed union 22, to which is attached the feed pipe 12 which is connected to the ram 1. (FIGURES l and 2.) The end-plate 17 has similarly a feed union 23 centrally disposed and admitting oil under pressure from the pump 165 through a control valve 166 (such as is described in US. patent application Ser. No. 801,254) to the inside of stationary tubular piston rod 24. Piston rod 24 carries at its right-hand end as viewed in FIG. 3 sealing rings 25; and its lefthand end (as viewed in FIGURE 3) is rigidly secured to plate 17. Sliding on the outside of piston rod 24 is a compound piston 26.- The outer and larger area portion of this component carries sealing rings 27, and the inner and smaller area portion 28 is open to the inside of the tubular piston rod 24. This smaller piston face 28 is pierced by a close-fitting hole 28a, which'inay have labyrinth grooves (not shown), and through which passes the tube 21. The left hand end of the tube 21 carries a valve 29, and this is held tightly to the end of tube 21 by valve spring 29a. At the right this operation will involve a delay of several seconds.

Secondly, while this large cylinder is filling, there is only the resistance of the retraction spring to be overcome, and as the piston area is relatively large, very little hydraulic pressure will be developed. The preferred control system'described in British patent specification No. 852,124, is of the self-cancelling type,-in that it is only held in the operating position by hydraulic pressure acting on a shoulder between two diameters of the control valve plunger. In the absence of such pressure tlie'control valve plunger is pushed to the oif position by a return spring and the equipment is immediately retracted by the spring means described above. The effect of this arrangement with the conventional two-stage ram is that the driver, on pulling out the valve control knob,.rnust hold it out for several seconds until pressure builds up upon the roller reaching the road and beginning to take the weight of the vehicle. If he pulls it out and immediately releases his hold on it, as would be-usual with other control panel knobs, it will simply snap back into the 011" position. Thisneed to hold out the knob may be regarded as an irritating inconvenience by the driver.

To overcome these difiiculties there is provided what may be termed an accelerator or hydraulic transformer which in essence comprises a small piston subjected directly to the hydraulic pressure generated by a pump and the resulting movement of which is transmitted to a larger piston and so rapidly displaces a quantity of hydraulic hand end of the tube 21 are ports 30 and 31. Extending from the disc 20 at the right hand end of the tube 19 to the inner face of the large diameter'flange 33 of the compound piston 26 is a compression spring 32. On the control valve 166 being operated and oil being admitted to the bore of union 23, the compound piston 26 is forced to the right in FIGURE 3 by pressure on face 28. The large piston face 33 then displaces the oil inside tube 16 and through the ports 31, 30 and the piping 12 connecting union 22 to each ram 1 and causes the first stage of these rams to be operated. Owing to the difference in areas between piston faces 28 and 33, and the fact that the ram retraction spring 32 must be stressed to operate the ram, a relatively high pressure will be developed at piston face 28. By suitable proportioning of piston faces 28 and 33 it can be arranged that this pressure is sufficient to hold out the control valve 166 in the operating position as described in US. patent application Ser. No. 801,254 and this high pressure will at the same time cause the compound piston to be driven rapidly to the right, as viewed in FIG. 3, with consequent rapid expansion of the first stage of the rams. When compound piston 26 reaches its right hand most position, the right hand end of the piston will pass over ports 30 and 31 in succession, thus cutting oif communicationbetween piston face 33 and the connection 22. When this movement is complete ports 30 will emerge on the left hand side of face 28 and oil will then be permitted to feed directly from one end of the transformer unit to the other, through the tubular parts 24 and 26 and the ports 30 and thus the full pump pressure can be brought to bear on the sec- 0nd or working stage of the rams, so as to enable them to lift the road wheels clear of the road and bring the rollers into contact with the tires 92.v

While the equipment is in action for the purpose of driving the vehicle sideways and the engine is running, oil pressure will be mantained at its maximum, and the flow from the pump will be bypassed through a relief valve (not shown). Pressure on face 28 will therefore maintain the compound piston in its right hand most position and leakage of pressure from the high pressure zone into the zone surrounding the tubular portion of compound piston 26 will be prevented by face-type oil-seal 34, which will come in contact with the right hand face 35 of compound piston. On the control valve 166 being pushed to the off position, pressure will disappear inside the tubular portion of compound piston 26 enabling spring 32 to move the piston 26 into its fully left hand position, as shown in FIGURE 3. The space to the right of major piston face 33 will thus be re-filled with the working fluid which is withdrawn from the interior of the rams. The retraction of the parking equipment may then be completed by the force generated in the rams by the retraction springs causing the valve 29 to be moved against the action of the springs 29a to the left, from the position shown in FIGURE 3, permitting the excess oil to flow from tube 21 through the ports 36 in valve 29 and thence back to the reservoir 169 associated with the pump and control valve 166 as described in US. patent application Ser. No. 801,254. FIGURES 4 and 5 show external views of the accelerator unit, wherein draw-bolts 37 and nuts 38 form a convenient method of holding the assembly together. This transformer unit may be inserted at any convenient point in the oil feed line between the control valve and the rams.

In using this parking device it is a possibility that an inexperienced driver might stall the engine through not opening the throttle sufficiently when moving sideways up a camber for example. Another possible error would be to move the car sideways with excessive power and speed owing to opening the throttle too far. If it was thought desirable to minimise either of these possibilities of error, this might be done by interconnecting the valve control rod 167 with a link 152, 153 which opened the throttle slightly to a fast tick-over speed when the valve control knob was pulled, i.e., to a speed slightly in excess of the normal idling speed with the vehicle stationary and the engine under no load, and which at the same time locked the normal accelerator control, so that the throttle could not be opened further beyond a small degree. Such an arrangement is shown diagrammatically in FIG- URE 6 wherein a carburetor 149 is mounted on an engine manifold 151, and has a throttle spindle 150. This throttle is normally operated by means of rod 152, and lever 153, shown on the remote side of the carburetor. The throttle spindle protrudes through the carburetor body on the nearside, as drawn, and carries a throttle stop piece 154, one arm 154a of which carries the normal slow running control screw 155. A support 156 fixed to the carburetor is formed with a circular hole 156a, wherein fits the enlarged end of rod 157. This end portion of rod 157 comprises a ramp 158, which is in contact with the end of the screw 155, or it may be in contact with a non-adjustable portion of the throttle mechanism. Another arm 154b of throttle stop piece 154 lies adjacent to a slot 163 in the support for rod 157, and in this slot a pin 159 lies and is secured to the end 160 of the rod 157. The other end of rod 157 is connected by a pin joint 161 to an extension 171 of the manipulating shaft 167.

On the valve 166 being operated by pulling the manipulating shaft 167 and extension 171 to the right, as drawn, the rod 157 will also be carried to the right and the ramp 158 will cause the carburetor throttle to be opened slightly by acting on screw 155. At the same time pin 159 will be moved to the right to a point opposite lever arm 15%; the effect of these movements is that, in the. first place, the throttle will be slightly opened to a fast tick-over speed suitable for normal sideways parking movements, and at the same time the pin 159 will prevent further excessive opening of the. throttle by blocking the path of lever arm 154b should the accelerator be depressed.

I claim:

A vehicle parking apparatus comprising two telescopic hydraulic rams disposed on opposite sides of the vehicle adjacent two of the vehicle road wheels, a hydraulic transformer supplying fluid pressure to both of said rams, a ground-engaging roller on a movable part of each of said rams, said hydraulic transformer being arranged between a source of fluid pressure and cylinder means of said rams and comprising a cylinder assembly and a compound piston having a small area part and a large area part reciprocable in said cylinder assembly, means for connecting the cylinder assembly at one end to the source of fluid under pressure so that one side of the small area part may be subjected directly to said fluid pressure, means for connecting the other end of said cylinder assembly to the telescopic rams so that movement of the compound piston toward said other end of the cylinder assembly causes the large area part of the piston to displace fluid from the cylinder assembly into the rams thereby rapidly extending them and bringing the rollers into engagement with the ground and with said wheels and continued extension of the rams lifts the wheels from the ground, and a valve mechanism actuated by relative movement between the compound piston and the cylinder assembly so that upon approach of the compound piston toward the other end of the cylinder assembly the valve mechanism causes the rams to be placed into direct communication with the source of pressure so that further extension of the rams takes place under load thereby lifting the vehicle, said rollers being rotatable by said vehicle wheels in a direction to swing the end of the vehicle sideways.

References Cited by the Examiner UNITED STATES PATENTS 2,345,165 3/44 White 6054.5 2,375,750 5/45 Campbell 605 4.6 2,399,270 4/46 Vickers 6O'-5 4.5

FOREIGN PATENTS 852,124 10/60 Great Britain.

A. HARRY LEVY, Primary Examiner.

LEO FRIAGLIA, Examiner.

Images