U.S. patent application number 10/263750 was filed with the patent office on 2004-04-08 for joint between a first cylinder and a second cylinder of a hydraulic jack to allow the second cylinder to drive the arm directly.
Invention is credited to Hsu, Kun-Shan.
Application Number | 20040065871 10/263750 |
Document ID | / |
Family ID | 32737245 |
Filed Date | 2004-04-08 |
United States Patent
Application |
20040065871 |
Kind Code |
A1 |
Hsu, Kun-Shan |
April 8, 2004 |
JOINT BETWEEN A FIRST CYLINDER AND A SECOND CYLINDER OF A HYDRAULIC
JACK TO ALLOW THE SECOND CYLINDER TO DRIVE THE ARM DIRECTLY
Abstract
A hydraulic jack includes a first cylinder, a handle pivotally
connected to the first cylinder to activate the first cylinder, a
second cylinder in communication with the first cylinder and having
a piston received in the second cylinder to connect to an arm so as
to support a seat on top of the arm. A pivotal shaft is provided at
a joint between the first cylinder and the second cylinder so that
the first cylinder is pivotally connected to the second cylinder by
means of the pivotal shaft.
Inventors: |
Hsu, Kun-Shan; (Chiayi City,
TW) |
Correspondence
Address: |
ROSENBERG, KLEIN & LEE
3458 ELLICOTT CENTER DRIVE-SUITE 101
ELLICOTT CITY
MD
21043
US
|
Family ID: |
32737245 |
Appl. No.: |
10/263750 |
Filed: |
October 4, 2002 |
Current U.S.
Class: |
254/8B |
Current CPC
Class: |
B66F 5/04 20130101 |
Class at
Publication: |
254/008.00B |
International
Class: |
B25B 023/00 |
Claims
What is claimed is:
1. In a hydraulic jack having a first cylinder, a handle pivotally
connected to the first cylinder to activate the first cylinder, a
second cylinder in communication with the first cylinder and having
a piston received in the second cylinder to connect to an arm so as
to support a seat on top of the arm, wherein the improvements
comprise: a pivotal shaft is provided at a joint between the first
cylinder and the second cylinder so that the first cylinder is
pivotally connected to the second cylinder by means of the pivotal
shaft, wherein the pivotal shaft has a guide path defined in the
pivotal shaft and having two ends, a first annular fluid passage
defined to communicate with one, end of the guide path and a second
annular fluid passage defined to communicate with the other end of
the guide path.
2. The hydraulic jack as claimed in claim 1, wherein the first
cylinder has a reservoir, an inlet communicating with the
reservoir, a control path communicating with the inlet, a drive
fluid path communicating with the inlet and the reservoir and a
transmission path communicating with the first annular fluid
passage.
3. The hydraulic jack as claimed in claim 2 further having a
release path selectively communicating with the transmission path
and the reservoir.
4. The hydraulic jack as claimed in claim 3 further comprising an
extension path provided to communicate the piston chamber to the
guide path.
5. The hydraulic jack as claimed in claim 1, wherein a joint
between the second cylinder and the arm is pivotal.
6. The hydraulic jack as claimed in claim 1, wherein a joint
between the second cylinder and the arm is pivotal.
7. The hydraulic jack as claimed in claim 3, wherein a joint
between the second cylinder and the arm is pivotal.
8. The hydraulic jack as claimed in claim 3, wherein a joint
between the second cylinder and the arm is pivotal.
9. The hydraulic jack as claimed in claim 4, wherein a joint
between the second cylinder and the arm is pivotal.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a hydraulic jack, and more
particularly to a joint between a first cylinder and a second
cylinder of a hydraulic jack to allow the second cylinder to drive
the arm directly.
[0003] 2. Description of Related Art
[0004] A conventional hydraulic jack is shown in FIG. 9, which has
a body (30) with multiple rollers (31) rotatably mounted on a
bottom of the body (30) to allow the jack to be moved, a cylinder
(40) mounted in the body (30) and having a piston rod (43)
extendable out of the cylinder (40), a push arm (35) pivotally
connected to a free end of the piston rod (43), an arm (32)
pivotally connected to a free end of the push arm (35) and having
two auxiliary arms (33) oppositely mounted on each side of the arm
(32) and a seat (34) mounted on top of the arm (32).
[0005] When this conventional hydraulic jack is in application, the
piston rod (43) moves in a direction as shown by the arrow, which
lifts the arm (32) as well as the two auxiliary arms (33) so that
if there is a load on top of the seat (34), the upward movement of
the arm (32) will lift the load on top of the seat (34).
[0006] However, with careful review of the design of the
conventional hydraulic jack, it is noted that when the cylinder
(40) is activated, the cylinder (40) applies a horizontal drive to
the push arm (35) so as to lift the arm (32). Furthermore, the two
auxiliary arms (33) on opposite sides of the arm (32) as well as
the push arm (35) take up a great deal of space in the body (30).
Therefore, the conventional hydraulic jack is excessively bulky
which hinders its practicability.
[0007] Furthermore, because the piston rod (43) indirectly drives
the arm (32), a great force is required to drive the arm (32).
[0008] Further still, because there are multiple joints in the
jack, smooth operation of the hydraulic jack is not easy to be
sustained.
[0009] To overcome the shortcomings, the present invention tends to
provide an improved joint between cylinders of a hydraulic jack to
mitigate and obviate the aforementioned problems.
SUMMARY OF THE INVENTION
[0010] The primary objective of the present invention is to provide
an improved joint between a first cylinder and a second cylinder of
a hydraulic jack so that when pumping the first cylinder, the
hydraulic fluid in the first cylinder is able to drive the second
cylinder directly.
[0011] Another objective of the present invention is that the joint
between the second cylinder and the arm is pivotal so that when the
second cylinder is activated by the first cylinder, the arm is able
to be lifted horizontally relative to the body of the hydraulic
jack.
[0012] Still another objective of the present invention is to
provide a first annular fluid passage and a second fluid passage in
the pivotal shaft that is used to connect the first cylinder and
the second cylinder so that whenever the pivotal shaft is rotated,
hydraulic fluid is able to flow into the second cylinder to lift
the arm.
[0013] Other objects, advantages and novel features of the
invention will become more apparent from the following detailed
description when taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a perspective view of the hydraulic jack of the
present invention;
[0015] FIG. 2 is a schematic view in partial section showing the
internal structure of the hydraulic jack of the present
invention;
[0016] FIG. 3 is an enlarged schematic view showing the internal
structure of the first cylinder relative to the second
cylinder;
[0017] FIG. 4 is a schematic cross sectional view showing the
structure of the pivotal shaft in relation to the fluid passage in
the first cylinder and the second cylinder;
[0018] FIG. 5 is a side plan view showing the activation of the
second cylinder by the first cylinder;
[0019] FIG. 6 is a schematic cross sectional view showing the flow
path of the hydraulic fluid in the first cylinder;
[0020] FIG. 7 is a schematic cross sectional view showing the flow
path of the hydraulic fluid in the second cylinder in relation to
the first cylinder;
[0021] FIG. 8 is a schematic cross sectional view showing the press
release mechanism of the hydraulic jack of the present invention;
and
[0022] FIG. 9 is a side plan view showing a conventional hydraulic
jack.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0023] With reference to FIGS. 1, 2 and 3, a hydraulic jack
constructed in accordance with the present invention has a body
(10) consisting of two side plates (11) each provided with a holder
(12) so that a user is able to hold the holder to move the body
(10) of the jack, a first cylinder (20) and a second cylinder
(24).
[0024] The body (10) further has an arm (13) pivotally connected to
a distal end of the second cylinder (24), rollers (131) rotatably
mounted on a bottom of the body (10), two auxiliary arms (14)
respective mounted on opposite sides of the arm (13) to support a
seat (15). A handle (26) is pivotally connected to one side of the
first cylinder (20) so as to activate the operation of the first
cylinder (20).
[0025] The first cylinder (20) has a first body (21) with a drive
fluid path (214) to receive therein a first piston (22) which is
provided with a guide rod (218) received in a slot (222) in the
drive shaft (22) and a resilient member (221) mounted around the
guide rod (218). A pressure release rod (23) is also connected to a
distal end of the handle (26) so that the pressure release rod (23)
is able to control the opening of a release path (216). The first
body (21) further has a reservoir (211) to receive therein
hydraulic fluid and an inlet (212) communicating with the reservoir
(211). The release path (216) communicates with the reservoir
(211). A control path (213) communicates with both the inlet (212)
and the drive fluid path (214) and is defined to receive therein a
unidirectional valve (217). On an upper portion of one side of the
control path (213), a transmission path (215) communicating with
the second cylinder (24) is formed and the release path (216) is
provided on the other side of the control path (213). Due to the
structure of the unidirectional valve (217) being conventional in
the art and the function thereof being well known to a skilled
person in the hydraulic jack field, detailed description about how
the unidirectional valve (217) works is omitted.
[0026] A pivotal shaft (27) is provided at a joint between the
first cylinder (20) and the second cylinder (24) and an extension
path (242) is provided between the reservoir (211) and the pivotal
shaft (27). An adjusting valve (28) (shown in dashed lines) may be
provided to adjust the pressure of the hydraulic fluid in the
hydraulic jack of the present invention.
[0027] With reference to FIG. 4, the pivotal shaft (27) has a guide
path (271) defined inside the pivotal shaft (27), a first annular
fluid passage (272) defined to communicate with one end of the
guide path (271) and the transmission path (215) and a second
annular fluid passage (273) defined to communicate with the other
end of the guide path (271) and the extension path (242). According
to the aforementioned communication relationships, hydraulic fluid
is able to flow back and forth between the first cylinder (20) and
the second cylinder (24).
[0028] The second cylinder (24) has a piston chamber (241) defined
to receive therein a second piston (25). The second piston (25)
together with the two auxiliary arms (14) pivotally connects to the
arm (13) and supports the seat (15).
[0029] With reference to FIGS. 5, 6 and 7, when the handle (26)
starts to pump the first cylinder (20) trying to lift the arm (13)
by the assistance of the second piston (25), the release path (216)
is blocked by the release rod (23). The hydraulic fluid in the
reservoir (211) flows to the drive fluid path (214) from the inlet
(212). When the pressure in the drive fluid path (214) starts to
build up, everytime the handle (26) moves downward to force the
hydraulic fluid in the reservoir (211) to flow into the drive fluid
path (214), the unidirectional valve (217) will be forced to
temporarily open to allow a portion of the, hydraulic fluid to flow
into the control path (213), the transmission path (215) and the
pivotal shaft (27). As best shown in FIG. 4, when the hydraulic
fluid enters the pivotal shaft (27), the hydraulic fluid enters the
first annular fluid passage (272), the guide path (271), the second
annular fluid passage (273) and the extension path (242) so that
the hydraulic fluid is able to be pumped into the piston chamber
(241) to drive the second piston (25) to lift the arm (13).
Therefore, when there is a load on top of the seat (15), the
driving force to the second piston (25) is able to lift the load on
the seat (15).
[0030] However, when lowering the load is required, the user
releases the pressure release rod (23) to open the release path
(216) while the unidirectional valve (217) still blocks the
communication between the control path (213) and the inlet (212).
After the release path (216) is opened, the hydraulic fluid in the
piston chamber (241) flows from the extension path (242) and flows
through the second annular fluid passage (273), the guide path
(271), the first annular fluid passage (272), the transmission path
(215) and into the release path (216) so that the hydraulic fluid
in high pressure in the piston chamber (241) is able to flow to the
reservoir (211). The second piston (25) is able to be retracted due
to the weight of the load.
[0031] According to the foregoing description, it is noted that the
joint between the first cylinder (20) and the second cylinder (24)
is pivotal and the pivotal shaft (27) at the joint between the
first cylinder (20) and the second cylinder (24) has a guide path
(271), a first annular fluid passage (272) to communicate with the
transmission path (215) and one end of the guide path (271) and a
second annular fluid passage (273) to communicate with the other
end of the guide path (271). Therefore, no matter how the pivotal
shaft rotates due to the lifting/downward movement of the arm (13),
hydraulic fluid is able to flow into/out of the piston chamber
(241). Still, because there is only a single joint between the
first cylinder (20) and the second cylinder (24), the hydraulic
pressure is able to drive the movement of the second cylinder (24)
smoothly.
[0032] Furthermore, the size of the hydraulic jack is reduced due
to the elimination of unnecessary linkage.
[0033] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size, and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
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