US2957734A - Hydraulic cylinder - Google Patents

Description

Oct. 25, 1960 s. B. MGLEOD HYDRAULIC CYLINDER 2 Sheets-Sheet 1 Filed Oct. 2, 1956 2,957,734 HYDRAULIC CYLINDER Stewart B. McLeod, Toledo, Ohio, assignor to Dura Corporation, a corporation of Michigan Filed Oct. 2, 1956, Ser. No. 613,425

1 Claim. crew-2 Thisinvention relates to hydraulic cylinders of the type used in hydraulic actuators for automobile tops,

hoods, deck-lids, seats, and the like, for folding beds, convertible furniture, etc.

i Cylinders designed for use in such applications-must be extremely compact and provide maximum piston stroke per inch of length because low automobile body silhouettes and modern furniture design allow space for disposition of power actuators.

Accordingly it is the primary object of my invention to provide an improved hydraulic cylinder which will satisfy the above requirements.

Another object is to provide a cylinder of the type specified which is more economical to build than those currently in use.

Still another object is to provide an improved cylinder with solenoid operated valve means incorporated therein for preventing movement of the piston except when the valve is open, said valve means including means for compensating for fluid expansion due to temperature changes.

Other objects and features of the invention will become apparent as the description proceeds when considered in conjunction with the accompanying drawings, wherein:

Fig. 1 is a longitudinal sectional view of a cylinder made in accordance with my invention;

Fig. 2 is a section along the line 2-2 of Fig. 1;

Fig. 3 is a section along the line 3-3 of Fig. 1;

Fig. 4 is a longitudinal sectional view of a cylinder incorporating a solenoid valve therein, a valve being shown in closed position;

Fig. 5 is a fragmentary section through the valve taken on line 55 of Fig. 4; and

Fig. 6 is a longitudinal section through the valve portion of the Fig. 4 cylinder showing the valve in open position.

Referring now to Figs; 1 to 3 inclusive, it will be seen that I have shown a cylinder having a body 10 and end castings 12 and 14. The body or casing 10 is made of metal tubing cut to desired length. The end castings 12 and 14 are preferably die cast. The casting 12 has an integral boss 16 provided with an opening 18 by means of which the cylinder may be mounted for hinging movernent. A cast chamber 20 provides clearance for one end of a piston rod 22 and is connected by a passageway 24 with a threaded opening 26 by means of which fluid may be introduced or withdrawn from the cylinder.

The other end casting 14 has a similar chamber 28, passageway 30 and opening 32. It is also provided with an integral internal boss 34 which provides sliding support for the piston rod.

It will be noted that the end castings 12 and 14 are each formed with a concentric outer groove. This groove 36 is of semi-circular shape and has a second concentric groove 38 of rectangular shape in its bottom wall. When the cylinder is assembled, an O ring 40 of compressible material is placed in the groove 38 by stretching the ring over the outer diameter of the end casting, and the end 2,957,734 Patented Oct. 25, 1960 of the tubing is crimped by rolling into the groove 36 asshown. The rolling operation crimps the tube end portion such that it firmly and tightly grips the end casting and the O ring is compressed such that the end of the cylinder is sealed against leakage.

' This connection of the tubing to the end castings constitutes an extremely important feature of my invention for the reasons that it. is easily and quickly accomplished with simple machinery, it requires minimum length of end casting and tubing to provide a firm connection and a strong seal, and any excess pressure in the cylinder that might occur under abnormal conditions of operation will tend to. bulge the tubing adjacent the end casting and draw the crimped portion into tighter gripping relation with the end casting groove.

a-rThe piston rod 22 is flared at its outer end 42 and :provided with an: opening for connection to any device or linkage tobe actuated thereby. The inner end of the rod .22 carries a piston 44fastened togthe rod by a staked nut 48. An 0 ring 46 is carried by the piston in a peripheral groove provided therein. The ring is compressed between the sides and bottom of the groove and the wall of the cylinder and provides a low-friction slid-ing seal.

Figs. 4 to 6 inclusive illustrate a cylinder incorporating a solenoid actuated valve in one end. This type of cylinder is used in instances where the power actuated device must be locked against movement in one or the other of its extreme positions or in an intermediate position.

In this form of the device, the construction of the cylinder, piston, etc., is similar to that previously described so the description will not be repeated.

In order to accommodate the solenoid valve assembly within the cylinder casing, a piston stop member 50 is disposed therein and is provided with an O ring seal 52. The stop 50 is recessed on its top side to accommodate the lower end of the piston rod and has a reduced portion 54 provided with a threaded opening 56 and a smaller opening 58. These two openings receive a valve seat 60 which has a passage 62 therein.

The seat 60 is retained in place by a nut 64 which has a threaded portion extending into the opening 58 as shown. The nut 64 has a shouldered axial opening which receives the solenoid sleeve 66. The latter is retained in the nut opening by flaring one end into a groove 68 formed in the nut. The other end of the sleeve has a press fit with an end member 70 which threadedly engages the lower cylinder head casting 12.

A plunger 72 is received within the sleeve 66 and has a conical end portion 74 which engages and closes the passage 62 when in the Fig. 4 position. The plunger has an internal axial passage 74 and a pair of longitudinal peripheral grooves 77 connecting with radial passages 76. A coil spring 78 disposed in the passage 74 urges the plunger into the Fig. 4 or closed position at all times.

A solenoid coil 80 surrounds the sleeve 66 and is retained in desired axial position by suitable washers and spacers as shown. Connections to the coil 80 may be brought out to suitable terminals (not shown) on the casing 10. An outer sleeve 81 protects the coil from hydraulic fluid that may leak past the seal 52 and positions the stop member 50 with respect to the end casting 12.

Fig. 4 illustrates the parts as they appear when the valve is in closed position. The plunger 72 is urged by the spring 78 against the seat 60 thereby closing the passage 62. Under these conditions, no fluid can enter or leave the cylinder at either end and thus piston 44 is locked against movement in whatever position it was in when the valve closed. The size of spring 78 is chosen such that movement of piston 44 is prevented thus making it possible for whatever linkage with which the piston rod is connected to be locked in desired position. How

ever, the spring 78 will perm-it the plunger 72 to be forced off its seat by abnormal pressure in the cylinder such as might be caused by an abnormal rise in temperature. In such event, the spring will yield before the bursting pressure. of the cylinder, hoses or fittings is reached and =fluid will be permitted to pass from the cylinder through passages 62, 76, 77, 78, 82, 84 and 24, and into the system reservoir (not shown).

In the ordinary operation of the cylinder, energization of the solenoid winding 80 simultaneously with operation of the means furnishing pressure fluid to the cylinder will cause the plunger to uncover the passage 62 and permit passage of fluid into or out of the cylinder in accordance with the direction of flow.

I claim:

An end closure for a hydraulic cylinder, said closure including a portion extending into the end of an associated cylinder and having an annular outer groove concentrically formed in the periphery thereof, said outer groove having a substantially radially aligned concentric inner groove in the bottom wall thereof, a yieldable sealing ring disposed in said inner groove, the end portion of said cylinder being crimped into said outer groove in sealing engagement with said sealing ring thereby to firmly secured said closure in place and seal the cylinder end against leakage.

References Cited in the file of this patent UNITED STATES PATENTS 150,347 Moser Apr. 28, 1874 807,865 Prescott Dec. 19, 1905 821,663 Mitchell May 29, 1906 1,875,068 Malby Aug. 30, 1932 2,389,824 Smith Nov. 27, 1945 2,468,943 Parsons May 3, 1949 2,479,398 Parsons Aug. 16, 1949 2,487,512 Berger Nov. 8, 1949 2,502,290 Szitar Mar. 28, 1950 2,574,273 McLeod Nov. 6, 1951 2,586,683 McLeod Feb. 19, 1952 20 2,673,130 Becker Mar. 23, 1954 FOREIGN PATENTS 507,616 Great Britain June 19, 1939

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