DE2922991A1 - HYDRAULIC PUMP FOR HOSPITAL BEDS - Google Patents

Description

description

The invention relates to a hydraulic pump according to the preamble of the main claim.

Such hydraulic pumps are particularly suitable for height-adjustable hospital beds, where in one Housing an oil container, at least one pump piston displaceable in a cylinder with an inlet valve, one on The outlet line connected to the pump cylinder with an outlet valve and a return line containing a backflow valve are provided, wherein the spherical valve body of the backflow valve can be moved in a guide by a The actuating rod can be actuated against the action of a spring and an axis with a Cam is provided for actuating the pump piston and for limiting the movement of the actuating rod of the non-return valve are.

In known pumps of this type, the outlet valve comprises a ball which is pressed against a valve seat by spring force will. If such a pump is used for hospital beds, it depends on the bed mass and the patient's weight caused back pressure so small that the ball is often not pressed tightly onto the valve seat. There-

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a small stream of oil seeps through it back into the oil container and the bed sinks slowly. To avoid these difficulties, the use of a ball is compulsory Very strong spring pressing against the seat is unsuitable, since such a strong spring opens the drain valve would disturb.

It is therefore the object of the invention to avoid the disadvantages occurring in the prior art and a To provide a pump of the above type in which there is no leakage of the drain valve.

The features indicated in the characterizing part of the main claim serve to solve this problem. This achieves that leakage of the outlet valve is effectively prevented by the shape of its valve body. The valve body is for this purpose of the exhaust valve elongated and has a polygonal cross-section, which with little play in an im Cross-section circular outlet pipe fits and at its end region facing the valve seat a groove with a has inserted O-ring, which lies on the valve seat when the exhaust valve is closed.

The elongated valve body with a polygonal cross-section cannot tip over and even then effectively seals the valve.

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sam when the spring acting on the valve exerts only a small force.

In the known pump there is a sudden closure of the return line when the return valve of its open position is brought into its closed position and the spherical valve body by the actuating rod has been pushed away from the valve seat. The lowering of a hospital bed with the help of the known pump is used this ended abruptly, which is extremely disadvantageous for seriously ill patients.

To avoid these disadvantages, the hydraulic pump described above is in a preferred embodiment with a Provided check valve, which has an O-ring shaped valve seat and in which the actuating rod of the check valve is provided with a head piece which, together with the O-ring, forms a narrow annular gap.

The fluid flowing back through the annular gap causes a braking effect. The transition from normal fluid backflow to the container for a completely sealing closure of the return line takes place progressively. the The end of a lowering process of a hospital bed is therefore practically completely smooth.

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The invention is explained in more detail below with reference to figures; show it:

Figure 1 is a perspective view of a hospital bed with a support frame and a hydraulic pump to raise or lower the bed;

FIG. 2 shows a longitudinal section through the hydraulic pump;

FIG. 3 shows an enlarged cross section through an outlet valve;

FIG. 4 shows a section along the line IV-IV in FIG. 3; and

FIG. 5 shows a longitudinal section through the return line the non-return valve.

Figure 1 shows a hospital bed with a couch 1 and a mobile frame 2. Between these two parts are hydraulic extendable supports 3 are provided. These supports consist of two telescopic cylinders, each of which is the upper can be moved upwards or downwards with the aid of a hydraulic piston. Each of the two hydraulic cylinders is over Hydraulic lines connected to one of two hydraulic pumps housed in a common housing 4 and are operated by a pedal 5.

Figure 2 shows a longitudinal section through one of the two pumps. An axis 6 of the pedal 5 extends through the pump

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housing 4. A cam 7 and a stop 8 sit on the axis 6. The two end positions of the cam 7 are through dashed lines shown.

The cam 7 is used to actuate a pump piston 9, which can be moved back and forth in a cylinder guide 11 is. The cylinder guide 11 sits in a cover 12. The free space in the housing 4 is filled with hydraulic oil.

An outlet line 13 is provided within the cover 12, one end of which extends into that of the cylinder guide 11 expanded space and its other end to a leads to a piston / cylinder unit of one of the hydraulic supports.

The cover 12 is pressed against the housing 4 by a screw bolt 15.

In the outlet line 13 there is an outlet valve 18, which is shown below will be described in detail. A return line 19 opens into the outlet line 13, the return line 19 being provided with a non-return valve 21 which is explained in more detail below.

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The piston 9 has one with the oil container in connection standing channel 22 which can be closed by an inlet valve 23. The inlet valve 23 comprises a ball 24, which is pressed by a spring 25 against a valve seat. The piston 9 is loaded by a spring 26 that pulls it out the cylinder guide 11 pushes out.

When the pedal 5 is depressed, the piston 9 is pressed by the nook 7 into the cylinder guide 11, whereby Hydraulic oil from the right part of the cylinder guide 11 according to Figure 2 is conveyed into the outlet line 13. The outlet valve 18 opens and hydraulic oil can enter the line stream. The inlet valve 23 is closed. When the pedal 5 is released, the piston 9 is moved by the spring 26 in Figure 2 pushed to the left. When the outlet valve 18 closes, a negative pressure in the right chamber of the Inlet valve 23 generated so that the ball 24 lifts against the action of the spring 25 from the associated valve seat. This allows hydraulic fluid from the oil tank through the Channel 22 and the opened inlet valve 23 flow into the right chamber of this valve, whereupon the ball 24 again is pressed against its valve seat.

For the return flow of hydraulic fluid from the supply line The return valve 21 located in the return line 14 must be opened to the oil container. This is done through a

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Actuating rod 28 which can be displaced in a guide 27. The guide 27 is attached to the cover 12. the Actuating rod 28 can be moved to the right by a stop 8 when the pedal is brought into its highest position will. When the backflow valve 21 is opened, liquid can flow from the line 14 into the backflow line 19, the backflow valve 21 and flow back through a channel 29 into the oil container.

In Figures 3 and 4 it can be seen that the valve body 31 of the outlet valve 18 is elongated and square Has cross-section with rounded corners. This valve body 31 is located in a region of the outlet line 13, which has a circular cross-section of relatively large diameter. The valve seat of the exhaust valve 18 is at the transition point from the smaller to the larger diameter of the outlet line 13. At the lower end of the valve body 31 a groove is provided in which an O-ring 32 is located. This O-ring 32 is when the exhaust valve is closed 18 on the associated valve seat.

The valve body 31 is moved into its closed position by a spring 33 pressed. Between the straight side walls of the valve body 31 and the cylinder wall of the outlet line 13 fluid can flow. Due to the elongated shape of the.

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Valve body 31 is prevented from tipping over. When the outlet valve 18 is closed, this seals itself only a small spring force of the spring 33 is reliable.

Figure 5 shows a preferred embodiment of the backflow valve 21, the actuating rod 28 for actuating the backflow valve being clearly visible. The valve body 34 of the non-return valve 21 is a ball which is pressed by a spring 30 onto a valve seat. The valve seat comprises a shoulder-shaped area with an O-ring 35, on which the ball 34 rests when the valve is closed. The operating rod 28 has an enlarged head piece 36 provided.

When the backflow valve 21 is closed, a narrow annular gap is formed between the enlarged head piece 36 and the O-ring 35 just before the ball 34 on the O-ring rests. The resulting narrow annular gap causes a slow flow interruption instead of a sudden one Interruption of the return flow.

The use of the above-described pump according to the invention for hospital beds leads to the fact that in a certain Height adjusted bed does not gradually decrease due to leakage of the outlet valve 18 and that upon termination the lowering movement of the bed with the help of the pedal 5,

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of the stop 8 and the actuating rod 28 no sudden interruption of the downward movement, but a gradual one Braking takes place.

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Claims (2)

U EXKÜ LL & STOLBERG ρηογκλιοηλι Htf'Hif.iMi * iivt'i PATE NI ANWAl 1 Γ HIlOHl IHI L UHOI I AN 1 'AI I NT O [I If Γ BESELERSTBASSF AD 2000 HAMBURG 53 DH JD FHHG DR DIPL ING JÜRGEN SUCHANTKE DIPL ING AFiNUtF HUBEH DR ALLARD from KAMEKE OR KARL HEINZ SCHULMEYER HOGEVEEN MACHINEFABRIEKEN BV (Prio: June 8, 1978 Marsweg 55 Netherlands No. 78.06248 - 15840) NL-8013 PE ZWOLLE Hamburg, June 1, 1979 Hydraulic pump for hospital beds claims 1. Hydraulic pump, especially for height-adjustable hospital beds, with an oil tank having housing, with a displaceable in a cylinder and having an inlet valve Piston, with an exhaust line connected to the cylinder with an exhaust valve, with a a return line having a return flow valve, the return flow valve having a spherical shape Has body which is displaceable in a guide against the force of a spring by an actuating rod can be actuated and wherein a shaft attached to a foot step with a nook for actuation of the piston and a stop for operating the actuating rod of the non-return valve serve, characterized in that the valve body (31) the outlet valve (18) is elongated 8S1 / 0742 ORIGINAL INSPECTED Has a shape with a polygonal cross-section and with little play in the outlet line, which is circular in cross-section (13) fits, whereby its end facing the valve seat has a groove for receiving an O-ring (32), which lies on the valve seat when the drain valve (18) is closed. 2. Hydraulic pump according to claim 1, characterized in that the backflow valve (21) has an O-ring-shaped seat (35) and that the actuating rod (28) of the backflow valve (21) is provided with a head piece (36) which, together with the O-ring seat (35), forms a narrow annular gap. 909851/07 L2