FI57649B - HYDRAULIK ELLER PNEUMATISK ANORDNING - Google Patents

Description

Γ1 ANNOUNCEMENT rn / iQ

• jggr · ib] <11) UTLÄGGNINGSSICRIFT 5 / o4y c (45)! v: (51) KY.ik.Va.3 P 15 B 11/04 // B 66 P 9/22 g Q | uj | FINLAND (21) P * t * nttlh * k * mu · - PattntaiwBknlng 766/73 (22) Haktmltpilvi - An * eknlng * dtg lU. 0 3 · 7 3 (23) Alkupllvl —GlltIghMsdig lfc.03.73 (41) Tullut | ulklMk «l - Bllvlt offontllg 25.09.73 PMKttl. j. r.kliteri controlled Mimmi »* - |. M | .ll »M„ * · ._

Patent- och ragisterttyralsan Antökan utlagd och utl. * Krlft * n publicirtd 30.05.80 _ (32) (33) (31) Requested privilege —Begird prlorltet 2 ^ .03.72

Sweden-Sweden (SE) 3859/72 (71) Ab Bygg- och Transportekonomi (BT), Svarvargatan 8, Mjölby, Sweden-Sverige (SE) (72) Anders Ivar Bryntse, Mjölby, Karl-Erik Berkestad, Linköping, Sweden This invention relates to a hydraulic or pneumatic device which includes a cylinder and piston arrangement for rapid movement and working movement, the device being specially designed for goods handling trolleys, e.g. fork lift trucks. Length of stay.

Known such fork cranes have a fixed transmission between the movement of the pump piston and the movement of the lifting piston. The transmission is arranged so that at the maximum load of the fork-crane it is possible to effect the movement of the pump piston by means of a manually operated lifting rod system. Thus, the transmission is not effective when lifting light loads or with an unloaded fork crane, as is later the case before the fork crane pushed under the load is pumped up into contact with the load. This height of the unladen lifting movement depends on the structure of the pallet and usually varies between 15-1 + 5 mm. the standard transmission of the jib crane is chosen so that the pump jet raises about 10 nm of motion on the lifting piston.

The object of the present invention is to provide an automatically load-dependent lifting piston movement, whereby the above-mentioned disadvantages can be largely eliminated.

2 57649

In other contexts, such devices are known. In such a device, a pressure medium is fed through a pipe fixed to the bottom of the cylinder, around which the lifting piston is movably mounted. Thus, an additional working chamber is provided, which is utilized to provide rapid movement.

It is fundamental to this invention that the cylinder, together with the piston rod, is shaped so as to form two working chambers outer relative to the piston rod. Thus, it is possible to feed the substance almost anywhere along the entire length of the cylinder. The structure also becomes simple and economical and has a minimum number of moving parts. The method is very well suited for cylinders with a short stroke length, such as in the case of fork lift cylinders, where the freedom to select the medium in question allows the cylinder according to the invention to be created, which is externally related to a well-established and well-justified embodiment.

The features of the invention are defined in the claims after the description.

The invention will now be described with reference to the accompanying drawing, which shows in longitudinal section a device according to the invention.

The drawing has 1 cylinder body, which includes two longitudinally integrated piston rod-shaped plungers 5 and 6. These have different diameters, of which the plunger 5 has a larger diameter, and the pistons are practically tightly and easily slidably guided against the cylinder body in controls 3 and 1. The length of the plungers 5 and 6 is determined by the requirement that they, when maximally extended, must still be guided in controls 3 and 1+. The plungers 5 and o are further provided with a central bore 7 »which together with the channels 8 and 10, the ball 11, the stop 12 and the valve hole 13 allows the pressure medium to pass from the working chamber 1U to the second working chamber 15, but not in the opposite direction, because the ball 11 then seals against the stop 12.

The cylinder body 1 also includes a reservoir 16 for the pressure medium and a passage 17 and 18, which allows the pressure medium to flow from the reservoir 16 into the working chamber 1U, but not in the opposite direction, since the valve ball 19 then seals against the stop 20.

The cylinder body further includes a passage 21 which, in a manner known per se, is connected to the pump during pumping up and lowering into the tank 16 by means of a valve system not shown here.

In addition, the cylinder body 1 in the hole 29 includes a valve consisting of a hole 22, a ball 23, a piston 2U, an O-ring 25, a spring 26 and a screw 27, 57649 provided with a hole 28. A piston 2h with an O-ring 25 is easily movable through the hole 29 regarding. When the spring-loaded valve opens, the channel 21 is connected to the working chamber IU via the channel 22, the ball 23 and the channel 30.

The device works in the following ways:

To cause the plungers 5 and 6 to protrude, the pressure medium is pressed, through a valve system known per se, through the channel 21 into the working chamber 15 and through the channels 8 and 10 into the bore 7, whereby the ball 11 is pressed tightly against the stop 12. Since the connection of the channel 21 with the working chamber IU is closed by pressing the ball 23 with the spring 26 by means of the piston 2h tightly against the opening of the hole 22, the pressure in the pressure medium affects only the surface corresponding to the difference between the plungers 5 and 6. Thus, a large amount of pressure gap is introduced, taking into account the large movement in the plungers 5 and 6, whereby pressure medium is also sucked from the container 16 through the channel 17, past the ball 19 and through the channel 18 into the working chamber 1U. When the plunger 5 and 6 are loaded so that the pressure of the pressure medium reaches a value such that the total force acting on the cross-sectional area of the hole 22 exceeds the spring force 2β, the ball 23 is depressed and the medium gets a free wedge in the chamber consisting of hole 29 and piston 2U, and through channel 30 to the working chamber IU. In this case, the ball 19 rises against the stop 20 of the knife and prevents the medium from flowing into the container 16. The pressure of the medium then immediately drops to a value corresponding to the load on the plungers 5 and 6 divided by the cross-sectional area of the piston 5. The screw 27 is provided with a hole 28 to ensure that the cross-sectional surface of the piston 2h facing the spring 26 is always under air pressure. Said connection does not always have to take place with the valve 23-29 shown and described here, but can be provided with a small gap or the like, whereby pressure equalization can take place at a certain piston rod load 11a and pumping speed. However, such a system is dependent on the viscosity of the pressure medium and also causes losses with the constriction caused by the gap. The described switch valve 23 ~ 29 is independent of viscosity differences and can in principle be made lossless.

In order to lower the plungers 5 and 6, the duct 21, via a valve system known per se, is connected to the tank 16, where there is always approximately atmospheric pressure. Thus, the pressure medium under overpressure in the working chamber 15 can flow freely into the tank 16, whereby the medium in the working chamber 1U also

Claims (2)

A hydraulic or pneumatic lifting device comprising a cylinder system through which pistons of different diameters pass coaxially and movably to enable a rapid stroke and a working stroke, characterized in that said pistons are two longitudinally interconnected first (5) piston rod-like plungers (5) the diameter in the lifting direction is larger than the diameter of the second (6) keel so that an annular abutment is formed between the two pistons, forming a first pressure surface of the pressure medium, the second pressure surface being formed from the end surface of the second piston (6), and two separate pistons formed in the cylinder (1); (5, 6) longitudinally separated working chambers (1U, 15), of which in the lifting direction the first (15) is in direct contact with the first pressure surface and the second (1U) is in direct contact with the second piston (6), the cylinder parts surrounding each piston (5, 6), kuk in separately is equipped with a separate input cable (21 resp. 22, 30) for a pressure medium, one of which (22, 30) is fitted with a shut-off valve (23) which opens under the action of the pressure of the medium only after it has reached a certain maximum value. Device according to Claim 1, characterized in that a channel (7, 8, 10) connecting the two working chambers (1U, 15) is arranged in the plunger (5, 6), in which a non-return valve (11, 12, 13) is arranged, which allows the flow of pressure medium between the working chambers (1U, 15) in only one direction, from the second working chamber to the first working chamber.