Hydraulic shock absorber and laboratory device

Abstract

A positioning foot having a hydraulic shock absorber with a fluid-filled hollow cylinder (210), in which a piston (220) that moves axially between an advanced, spring prestressed position and a retracted position. The piston separates a front axial fluid space (214) and a rear axial fluid space (215) from one another in the hollow cylinder. Both fluid spaces are connected to one another in a fluid exchanging fashion via at least one throttle opening (223) in the piston. The piston is rigidly connected to a piston rod (221), which passes through the front fluid space and abuts a fixed stop (218) in the retracted position, in which the volume of the rear axial fluid space is minimized and the volume of the front axial fluid space is maximized. The spring prestress is dimensioned so that the weight of the device body moves the piston dampingly into the retracted position.

Claims

1. Laboratory device comprising: a device body installed on a plurality of positioning feet attached to the device body, wherein at least one of the positioning feet comprises a fluid-filled hollow cylinder, in which a piston is configured to move axially between an advanced position supported with a spring prestress, and a retracted position counter to the spring prestress, wherein the piston separates a front axial fluid space and a rear axial fluid space from one another in the hollow cylinder, wherein both fluid spaces are connected to one another in a fluid exchanging fashion via a plurality of throttle openings in the piston, wherein the piston is rigidly connected to a piston rod, which passes through the front fluid space, and abuts a fixed stop in the retracted position, in which the volume of the rear axial fluid space is minimized and the volume of the front axial fluid space is maximized, wherein the spring prestress is dimensioned such that the weight of the device body, which exerts a load when the laboratory device is installed on the positioning foot, is sufficient to move the piston into the retracted position in a damped manner and wherein the throttle openings are arranged in the piston to be sealed in succession by an inner wall of the hollow cylinder as the piston moves axially from the advanced position to the retracted position.

2. Laboratory device, as claimed in claim 1, wherein the at least one positioning foot is configured as a hydraulic shock absorber arranged vertically adjustably on the device body of the laboratory device.

3. Laboratory device, as claimed in claim 1, wherein the hollow cylinder comprises an external thread, which is screwed into a corresponding internal thread on the device body, as well as a rotating actuating element that is rigidly connected to the hollow cylinder.

4. Laboratory device, as claimed in claim 1, wherein the hollow cylinder comprises an external thread, which is screwed into a corresponding internal thread on the device body, wherein the internal thread is mounted on the device body to allow rotational motion, and further comprising a motorized rotational drive.

5. Laboratory device, comprising: a device body installed on a plurality of positioning feet attached to the device body, wherein at least one of the positioning feet comprises a fluid-filled hollow cylinder, in which a piston is configured to move axially between an advanced position supported with a spring prestress, and a retracted position counter to the spring prestress, wherein the piston separates a front axial fluid space and a rear axial fluid space from one another in the hollow cylinder, wherein both fluid spaces are connected to one another in a fluid exchanging fashion via at least one throttle opening in the piston, wherein the piston is rigidly connected to a piston rod, which passes through the front fluid space, and abuts a fixed stop in the retracted position, in which the volume of the rear axial fluid space is minimized and the volume of the front axial fluid space is maximized, wherein the spring prestress is dimensioned such that the weight of the device body, which exerts a load when the laboratory device is installed on the positioning foot, is sufficient to move the piston into the retracted position in a damped manner wherein the piston comprises in the piston side wall a plurality of throttle openings, which connect the axial fluid spaces, and of which the further the piston is moved out of the advanced position in the direction of the retracted position, the more are closed by an inner wall projection of the hollow cylinder, and wherein the inner wall projection rests against the piston side wall.

6. Laboratory device, as claimed in claim 1, wherein a plurality of the positioning feet are attached to the device body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings show in:

(2) FIG. 1: the bottom plate of the device body of a laboratory device with three positioning feet in accordance with the present invention;

(3) FIG. 2: a perspective view of a single positioning foot;

(4) FIG. 3: a partially hidden sectional view of the positioning foot from FIG. 2;

(5) FIG. 4: a schematic representation of a shock absorber, used in accordance with the invention, in its advanced position;

(6) FIG. 5: the shock absorber from FIG. 4 in its retracted position.

DETAILED DESCRIPTION

(7) Identical reference numerals in the figures indicate the same or analogous elements.

(8) FIG. 1 shows a perspective view of the bottom plate 110 of a laboratory device 100, which, moreover, is not shown in greater detail. Said laboratory device comprises three positioning feet 200, which are implemented, according to the invention, in the form of industrial shock absorbers that are reallocated for a different purpose. For a more detailed description of the positioning feet 200, reference is made to FIGS. 2 to 5.

(9) FIGS. 2 and 3 show a perspective or alternatively a partially hidden sectional view of a positioning foot 200, which is screwed with the external thread 211 of its hollow cylinder 210 into an internal thread 111 of a support plate 112, which is rigidly connected to the bottom plate 110. The “special features” of the hollow cylinder 210 will be described below in the context of FIGS. 4 and 5.

(10) A piston rod 221 protrudes downwards from the hollow cylinder 210; and a head 222, which is pointed in the manner of a truncated cone, is arranged on the distal end of said piston rod. The piston rod 221 can be moved axially relative to the hollow cylinder 210 that is screwed into the support plate 112. A knurled wheel 213 is fixed to the external thread 211 of the hollow cylinder 210 with a lock nut 212, so that the hollow cylinder 210 can be rotated by manual rotation of the knurled wheel 213; and, thus, the positioning foot 200 can be vertically adjusted, on the whole, with respect to the bottom plate 110.

(11) FIGS. 4 and 5 show an industrial shock absorber, which is used, according to the invention, as a positioning foot 200, in an oversimplified schematic representation. A cup-shaped piston 220 is arranged in the hollow cylinder 210 in such a way that it is axially displaceable. The piston 220 is permanently connected to the piston rod 221, which passes through the front end face of the hollow cylinder 210 in a sealing manner. The seal may be arranged in the passage of the piston rod 222 through the front end face of the hollow cylinder 210. However, other sealing measures are also conceivable, such as, for example, the arrangement of a sealing rolling diaphragm or the like.

(12) The piston 220 is prestressed with a prestress spring 230 in its advanced position shown in FIG. 4. Said piston divides the interior of the hollow cylinder 210 into a front axial fluid space 214 and a rear axial fluid space 215. In FIG. 4, the front axial fluid space 214 is minimized in size, whereas the rear axial fluid space 215 is maximized in size. In FIG. 5, these ratios are reversed. The fluid spaces 214, 215 are connected to each other via breakthroughs 223 in the side wall of the piston 220.

(13) Starting from the non-loaded advanced position shown in FIG. 4, a shock absorber, which is used as a positioning foot 200, is subjected to an axially directed force on the piston rod 221 of said shock absorber when the laboratory device of the present invention is placed on a base plate. This results in a displacement of the piston 220 counter to the spring prestress of the spring 230, so that the damping fluid, with which the cavity of the hollow cylinder 210 is filled, flows from the rear axial fluid space 215 through the throttle openings 223 into the front axial fluid space 214. As a result of the fluid flow friction, the axial movement of the piston 220 is damped.

(14) During the immersion of the piston 220, the throttle openings 223 pass successively a shoulder 216 of an annular projection 217 in the interior of the hollow cylinder 210 and in this way are sealed one after the other in succession. Therefore, the total amount of the flow path that is available between the two axial fluid spaces 214, 215 decreases with the immersion of the piston 220, so that the resulting damping increases. The piston 220 comes to a standstill at the rear stop 218 in its retracted position shown in FIG. 5.

(15) In the inventive design of the positioning foot 200 the intrinsic weight of the laboratory device 100, which exerts a load on the positioning foot 200, is sufficient to transfer the piston 220 from its advanced position (FIG. 4) into its retracted position (FIG. 5) or, more specifically, upon transfer, to hold said piston in its retracted position counter to the spring force of the spring 230. Thus, the result is that the laboratory device is always installed gently, so that deleterious accelerations on delicate elements of the laboratory device are avoided, but at the same time it is achieved that the mounted laboratory device stands on its base without elastic, vibration-susceptible intermediate elements.

(16) The embodiments that are discussed in the specific description and shown in the figures represent exemplary embodiments of the present invention that are shown only for illustrative purposes. The person skilled in the art in question is given in light of the disclosure herein a wide range of possible variations.

LIST OF REFERENCE NUMERALS

(17) 100 laboratory device 110 lower shell of 100 111 internal thread of 112 112 support plate of 110 200 positioning foot 210 hollow cylinder 211 external thread of 210 212 lock nut 213 knurled wheel 214 front axial fluid space 215 rear axial fluid space 216 shoulder of 217 217 annular projection 218 end stop 220 piston 221 piston rod 222 head of 221 223 throttle opening 230 return spring