GB2045140A - Supporting device - Google Patents

Abstract

A supporting device for supporting an article (1), e.g. a piston rod to be force-fitted into a piston (4), having a recess (1a) in the end surface thereof, comprises a main body (5) in which two pistons (6 and 7) are coaxially disposed, the pistons respectively supporting the annular end face of the article and the inner face of the bore. An enclosed chamber (8) is defined in the main body by the two pistons, and a force- transmitting deformable material (9), e.g. oil, rubber, or granular material, is contained in the enclosed chamber to transmit a force between the pistons such that, when one piston ingresses into the main body, the other piston egresses out of the main body. An axially extending through bore (6d) is formed in one piston. A force-receiving area (B) is defined on one piston (6) and around the bore (6d), and a force- receiving area is defined on the other piston (7) and is axially aligned with the bore (6d). A projection instead of a recess may be provided on the article. <IMAGE>

Description

SPECIFICATION Supporting device This invention relates to a supporting device and particularly to a device or anvil structure adapted for supporting an article (referred hereinafter as one article) in performing operations, such as force- fitting operations or the like, in which the article is connected integrally with another article by applying a pressing force. The device supports the one article and receives the pressing force. Such force-fitting operations are usually performed e.g. to integrally connect a piston of a cylinder device with one end a piston rod orto integrally connect one end of an output rod of a force multiplying pneumatic device with a piston member which receives the output force from a power piston.

However, a threaded hole or the like is usually formed in the other end of the piston rod or the output rod for connecting with a third article, such as a push rod for transmitting, e.g., the output force to a piston of a master cylinder, thus, the force fitting operation has been performed by supporting an annular surface area surrounding the hole formed in the rod or by supporting the inner end of the hole with a rod-shaped portion of the supporting device.

But the area supporting the pressing force is restricted very much and, therefore, a desired large pressing force cannot be applied. As a result, the two articles cannot be interconnected reliably and, the connection therebetween will sometimes be released during long period of usage.

An object of the invention is to prevent the shortcomings aforementioned and, to provide a supporting device having a large force-receiving area as compared with prior art devices.

The supporting device according to the invention comprises a main body, two pistons disposed coaxially in the main body and being displaceable respectively in the axial direction, a forcetransmitting deformable material enclosed in a closed chamber defined in the main body and acting on the pistons such that when one of the pistons ingresses into the main body the other piston egresses out of the main body and when the other piston ingresses into the main body the one piston egresses out of the main body, an axially extending through bore formed in one of the pistons, a force-receiving area defined on the one piston and around the through bore, and a force-receiving area defined on the other piston which aligns axially with the through bore.

Some preferred embodiments of the invention will be described, by way of example, with reference to the drawings, in which: Figure 1 is a schematic sectional view of a prior art device; Figure 2 is a view similar to Figure 1 but showing another prior art device; Figure 3 is a longitudinal sectional view of a supporting device according to the invention; Figure 4 is a view similar to Figure 3 but showing a second embodiment of the invention; Figure 5 is a view showing a third embodiment of the invention; and Figure 6 is a view showing a fourth embodiment of the invention.

In the prior art device shown in Figure 1, an output rod or the one article 1 is supported on a supporting device 3 which is mounted on a base 2. A rod portion 3a of the supporting device 3 is inserted into a threaded bore 1 a of the output rod 1 to bottom the inner end 1 d thereof. A piston or the second article 4 having a recessed portion 4a is located above the output rod 1 with the recessed portion 4a facing a projecting portion 1 b of the output rod 1. By utilizing a hammer or the like (not shown) a pressing force f is applied on the piston 4 so as to forcibly engage the recessed portion 4a with the projecting portion 1 b. In Figure 2, the lower end 1c of the output rod 1 is directly supported on the base 2 which acts as the supporting device.In either case, the pressing force f is received by a relatively restricted area portion of the inner end id of the threaded bore 1 a (Figure 1), or of an annular surface portion 1 c defined around the bore la of the output rod 1; thus, it has been difficult to apply a large pressing force.

In Figure 3, the output rod 1 is supported on a supporting device of the present invention which comprises a main body 5 mounted on the base 2, a first piston 6 slidably fitted in a recess or bore 5b of the main body 5, and a second piston 7 disposed coaxially with the first piston 6 and slidably mounted in an inner cylindrical surface portion 6b of the first piston 6. The first piston 6 has a generally inverted cup-shaped form defining the upper surface 1a, the lower surface 6c and the inner cylindrical surface 6b, and has a central bore 6d. The second piston 7 has a rod portion 7a freely penetrating the bore 6d of the first piston 6 and projecting upwardly of the supporting device. A closed chamber 8 is formed in the bottom portion of the recess 5b and its upper end is defined by the bottom surfaces 6c and 7c of the pistons 6 and 7.Aforce-transmitting deformable material 9 is enclosed in the chamber 8. The force-transmitting deformable material may be liquid such as oil or water, a resilient material, such as rubber or the like, fine granular material; such as powder of any suitable material, or a highly viscous material. The material 9 is required to transmit the force received from either of the pistons 6 or 7 to the other piston 7 or 6; however, highly compressible materials such as gas or the like are not preferable.

In the illustrated embodiment, oil has been introduced into the chamber 8 through a passage 10, and a plug 11 closes the passage 10. Seal members 12 and 13 are arranged in the sliding portions between the main body 1 and the first piston 6, and between the first and the second pistons 6 and 7.

In operation, the rod portion 7a of the second piston 7 is inserted into the bore 1a of the one article or output rod 1, and the lower end ic of the rod 1 is mounted on the upper surface 6a of the first piston 6 and, thereafter, a force-fitting operation is performed by applying a force F on the second article or piston 4. The lower end lcofthe rod 1 tightly abuts with the upper surface 6a of the first piston 6, and the upper end of the rod portion 7a of the second piston 7 tightly abuts with the inner end Id of the bore 1a of the output rod 1. Hereinafter, the latter abutting portion is referred as abutting portion A, and the former abutting portion is referred as abutting portion B.Firstly, it is supposed that the rod 1 is, in the initial stage, supported by only one of the abutting portions A or B owing to the difference between the depth C of the bore 1a of the output rod 1 and the length of the rod portion 7a of the second piston 7 as measured from the upper surface 6a of the first piston 6. When the force F is applied on the output rod 1 the first and the second pistons relatively move in the vertical directions by virtue of the force-transmitting material 9 so that both of the abutting portions A and B act reliably.

More particularly, it is assumed that the depth e of the bore 1a is shorter than the projecting length of the rod portion 7a of the second piston 7 in the initial stage, so that the abutting portion B is separated when the abutting portion A is engaged, and the pressing force F is applied to the piston 4. Thus, the second piston 7 is displaced downwardly and a force is transmitted through the material 9 to the first piston 6, whereby the first piston 6 is displaced upwardly and the upper surface 5a of the first piston 6 engages with the open end 1 c of the output rod 1 (the abutting portion B engages), whereby, the force F is received by the abutting portions A and B.

Preferably, both of the abutting portions are brought into the engaging conditions by manually applying a pressing force on the output rod 1 to displace either of the pistons 6 or 7 downwardly, thereby displacing the other piston 7 or 6 upwardly prior to applying the pressing force F.

Let a1 be the cross-sectional area of the inner end id of the output rod 1 or the abutting area of the abutting portion A, a2 be the cross-sectional area of the open end 1c of the output rod 1 or the abutting area of the abutting portion B, S, be the crosssectional area of the bottom surface 6c of the first piston 6 which is exposed to the material 9, S2 be the cross-sectional area of the second piston 7 which is exposed to the material 9, F1 be the component of the force F acting on the abutting portion A, and F2 be the component of the force F acting on the abutting portion B.By making the areas S, and S2 proportional to the areas a1 and a2, the following equation can be obtained: al/a2 = S1/S2 = F1/F2 Therefore, the stresses ol and a2 generated respec tively in the abutting portions A and B are equal as shown in the following equations: ol = F1/a1 and a2 = F2,a2, thus ai = In the second embodiment of the invention shown in Figure 4, the first and the second pistons 6 and 7 are separately mounted in the main body 5. The main body 5 consists of an upper main body 5' and a lower main body 15'.

The upper main body 5' and the lower main body 15' have recesses or cylinder chambers 5'b and 15'b respectively for slidably receiving therein a first piston 6' and a second piston 7'. A rod 7'a of the second piston 7' slidably and fluid-tightly passes through a partition wall 5'e which partitions the cylinder chambers 5'b and 1 5'b and through a through bore 6'd which is formed in the first piston 6'. A first closed chamber 8' is formed in the bottom portion of the recess 5'b and is exposed to the bottom surface 6'c of the first piston 6', and a second closed chamber 18' is formed in the bottom portion of the recess 1 5'b and is exposed to the bottom surface 7'c of the second piston 7'. The chambers 8' and 18' are intercommunicated by passages 10 and 10'.The chambers 8' and 18' contain therein the pressure transmitting material 9.

The operation of the second embodiment is similar to that of the first embodiment and, detailed description therefor is omitted.

In the third embodiment shown in Figure 5, the second piston 7" is fitted slidably in the recess 5b of the main body 5 and the first piston 6" is slidably received in a recess 7"b formed in the second piston 7" with a rod portion 7"a of the second piston 7 extending slidably through a bore 6"d which is coaxially formed in the first piston 6". A first closed chamber 8" is formed in the bottom portion of the recess 7"b. A second closed chamber 18" is formed in the bottom portion of the recess 5"b and is permanently communicated with the first closed chamber 8" through passages 10". The operation of the third embodiment is similar to that of the first embodiment and, detailed description therefor is omitted.

The fourth embodiment shown in Figure 6 does not have the rod 7a of the first embodiment and is adapted for supporting an output rod 1 having a projection 1 e formed on the lower end thereof. The projection 1 e has external screw threads formed there-around forthreadingly engaging with a third article (not shown). The projection 1e extends through a bore 6"'d which is formed in first piston 6"', and the lower end of the projection le abuts with the second piston 7"' at an area which is axially aligned with the bore 6"'d of the first piston 6"'. An annular shoulder portion 1f defined by the projection 1 e abuts with the first piston 6"'. The operation of the fourth embodiment is similar to that of the first embodiment.

It will be noted that the present invention is not limited by the embodiments heretofore described and, many changes or modifications may easily be made.

The rod 7a (7'a or 7"a) is integrally formed on the second piston 7 (7' or 7") in the illustrated embodi ments, but the rod 7a may be formed separately from the second piston and may be removably connected thereto or simply abutting with the second piston.

As described heretofore, the supporting device according to the invention can receive a large pressing force, in utilizing the device in e.g. force fitting operation, by a large force receiving area which is defined by the sum of, irrespective to the depth of the bore or the height of the projecting portion, the cross-sectional area of (the inner end of) the bore and the annular area of the open end of the bore, or the cross-sectional area of the projecting end of the projection and the annular area of the shoulder surrounding the projection. Thus, reliable connection can be formed by the force-fitting operation.

Further, an impact force effected in the forcefitting operation can be received through the forcetransmitting material on the main body; thus, the main body will not receive any locally concentrated stress and the service life of the device will be extended.

Further, in performing the force fitting operation or the like for forcibly connecting the one article with another article, the rod shaped portion extending from the second piston is inserted in the bore of the one article and the annular shaped edge of the one article is supported on the first piston when a bore is formed in the lower end of the one article; or the projection formed in the lower end of the one article is inserted through the opening formed in the first piston and is supported on the second piston and the annular shoulder formed on the base portion of the projection is supported on the first piston when the projection is formed on the lower end of the one article; thus, the one article can reliably be maintained at the vertical condition even when the one article has an elongated form, such as an output rod orthe like, and the force-fitting operation can easily be performed.

Claims (7)

1. A supporting device comprising a main body, two coaxial pistons displaceably disposed in the main body, a force-transmitting deformable material containd in an enclosed chamber which is defined in the main body and by the two pistons, said pistons being associated with one another by the forcetransmitting material such that, when one of the pistons ingresses into the main body the other piston engresses out of the main body, an axially extending through bore formed in a first of the pistons, a force-receiving area defined on one surface of said first piston and around the through bore, and a force-receiving area defined on one surface of the second piston and axially aligning with the through bore.

2. A supporting device as claimed in claim 1, wherein the force-receiving areas defined on the pistons coact to receive an axial force applied on one article which is supported on the device.

3. A supporting device as claimed in claim 1 or 2, wherein the force-receiving area of said first piston multiplied by the cross-sectional area of said second piston exposed to the force-transmitting material is equal to the force-receiving area of said second piston multiplied by the cross-sectional area of said first piston exposed to the force-transmitting material.

4. A supporting device as claimed in claim 1,2 or 3, wherein one of said pistons is slidably fitted in a bore formed in the main body, and has a coaxial bore in which the other piston is slidably received.

5. A supporting device as claimed in claim 1,2,3 or 4, in which the force-receiving area of said second piston is defined on a rod portion of said second piston which extends through the through bore of said first piston.

6. A supporting device as claimed in claim 5 in which said rod portion extends through said chamber and is sealed to said through bore.

7. A supporting device constructed substantially as herein described with reference to and as illustrated in the drawings.