US20050146252A1

US20050146252A1 - Cylinder apparatus with a capability of detecting piston position in a cylinder

Info

Publication number: US20050146252A1
Application number: US10/747,048
Authority: US
Inventors: Yun-Ching Chuang
Original assignee: KSP Tech Corp
Current assignee: KSP Tech Corp
Priority date: 2003-12-30
Filing date: 2003-12-30
Publication date: 2005-07-07

Abstract

A cylinder apparatus with a capability of detecting a piston position includes a cylinder, a throttling valve, a positive limit and a pressure switch. A piston is movably mounted in the cylinder. A piston rod with an outside end protruding out of the cylinder is attached to the piston and adapted to push an object. The cylinder is connected to a pump with pipes. The throttling valve and the pressure switch are connected to the pipes, and the pressure switch is installed between the cylinder and the throttling valve. Consequently, when the pump starts pumping, the piston rod pushes the object to abut the positive limit. The stopped movement of the piston rod will change the pressure in the cylinder that triggers the pressure switch to send a signal to a controlling host to stop the pump.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a cylinder apparatus, and more particularly to a hydraulic or pneumatic system cylinder apparatus with a capability of detecting a piston position in a cylinder of the cylinder apparatus.
2. Description of Related Art
In most hydraulic and pneumatic powered devices, cylinder apparatuses are the basic actuating elements. With reference to FIG. 4, a conventional cylinder apparatus with a capability of detecting a piston position includes a cylinder (50), reed switches (54) and permanent magnets (521). The cylinder (50) generally includes a closed tubular housing (51), a piston (52) and a piston rod (53). Since operation of the cylinder (50) is conventional, no description of the cylinder (50) operation is provided.
The conventional method of detecting the piston (52) position in a cylinder (50) uses the permanent magnets (521) and reed switches (54). The permanent magnet (521) is ring shaped and mounted around the piston (52). The reed switches (54) are respectively strapped to specific positions on the closed tubular housing (51). When the piston (52) moves toward top dead center or bottom dead center in the closed tubular housing (51) and passes a reed switch (54), the magnetic field of the permanent magnet (521) will trigger the reed switch (54). The reed switch (54) will send an electric signal to a host (not shown) that controls the entire system and stops or starts the piston moving and determines the direction of movement.
However, the conventional cylinder apparatus with a capability of detecting the piston position in the cylinder (50) still has the following shortcomings.
1. Inconvenient Operation:
Because the reed switch (54) is strapped or clamped on the closed tubular housing (51), the reed switches (54) must be repeatedly unclamped and clamped to change or adjust the piston (52) position in the cylinder (50) to push an object to a required position. Especially, when the cylinder (50) is mounted inside a complex machine, unclamping or clamping the reed switches (54) is not easy and is inconvenient.
2. Limited Application:
As described in the foregoing description, the reed switches (54) sense the magnetic field induced by the permanent magnets (521) and send out an electric signal to the host. However, if the conventional cylinder apparatus is used in a machine that has a strong magnetic field around or in the machine, the reed switches (54) will sense the strong magnetic field and lose its capability to sense the position of the piston (52) correctly. Therefore, applications of the cylinder apparatus are significantly diminished and can only be used in machines that do not have strong magnetic fields. To overcome the shortcomings, the present invention provides a cylinder apparatus with a capability of detecting a piston position in a cylinder of the cylinder apparatus to mitigate or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

The main objective of the invention is to provide a cylinder apparatus with a capability of detecting a piston position that is convenient to use.
Another objective of the invention is to provide a cylinder apparatus that can be broadly used in any hydraulic and pneumatic device.
Other objectives, 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

FIG. 1 is a block diagram of a cylinder apparatus in accordance with the present invention used in a simple hydraulic system;
FIG. 2 is a schematic diagram of the cylinder apparatus in FIG. 1 used in a simple hydraulic system;
FIG. 3 is a schematic diagram of an alternative embodiment of the cylinder apparatus used in a simple hydraulic system; and
FIG. 4 is a side plan view of a conventional cylinder apparatus with a capability of detecting piston position in a cylinder.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

With reference to FIGS. 1 and 2, a cylinder apparatus with a capability of detecting piston position comprises a cylinder (10), pressure switches (20), throttling valves (30, 30′) and a positive limit (40). The cylinder apparatus can be used in a hydraulic system or a pneumatic system. A double-acting cylinder with a piston rod used in a hydraulic system is described, but a person skilled in the art will recognize that a single-acting cylinder or a double-acting cylinder with two opposite piston rods can be used.
The cylinder (10) is connected to a pumping device (not numbered) of the hydraulic system. The pumping device has a pump (60), pipes (not numbered) and directional control valves (61). The pump (60) is electrically connected to a controlling host (not shown) and pumps hydraulic fluid into the cylinder (10) via the pipes.
The cylinder (10) includes a closed tubular housing (11), a piston (12) and an actuating device (not numbered). A complex hydraulic system can be constructed with the pump (60), the directional control valves (61) and the pipes, and a sophisticated cylinder (10) can also be constructed with the closed tubular housing (11), the piston (12) and the actuating device. A chamber (not number) is defined in the closed tubular housing (11), and the piston (12) is movably mounted in the chamber to move reciprocally in the closed tubular housing (11) and splits the chamber into a protruding chamber (111) and a retracting chamber (112). The actuating device is attached to the piston (12) and is adapted to push or carry an object to a proper position, where a next process will deal with the object. The actuating device in this preferred embodiment is a piston rod (13) with an inside end (not numbered) and an outside end (not numbered). The actuating device could be a carrier (not shown) attached to the piston (12) to carry the object for rodless cylinders, such as magnetic rodless cylinders. The inside end of the piston rod (13) is attached to the piston (12) in the closed tubular housing (11). The outside end of the piston rod (13) protrudes out of the closed tubular housing (11) and is adapted to push the object, such as a bottle (41) to a proper position.
The protruding and the retracting chambers (111, 112) are respectively connected to the pump (60) by means of the pipes through a directional control valve (61). The directional control valve (61) is connected to the pipes between the pump (60) and the cylinder (10) and is used to change the path of the hydraulic fluid pumped out of the pump (60) into the two chambers (111, 112). A throttling valve (30′) is connected to the pipes between the directional control valve (61) and the protruding chamber (111) in the closed tubular housing (11) and is used to control the flow rate of the hydraulic fluid flowing into or out of the protruding chamber (111). Therefore, the piston rod (13) can smoothly move out of the closed tubular housing (11) or smoothly retract into the closed tubular housing (11) by changing the path and the flow rate of the hydraulic fluid into the different chambers (111, 112). A one-direction throttling valve (30) is connected to the pipes between the directional control valve (61) and the retracting chamber (112) in the closed tubular housing (11) and throttles the flow rate of the hydraulic fluid flowing out of the retracting chamber (112). The pressure switch (20) is connected to the pipes between the one-direction throttling valve (30) and the retracting chamber (112) and can be triggered by a pressure change in the retracting chamber (112). The pressure switch (20) can convert a physical signal to an electrical signal and send the electrical signal to the controlling host that controls the pump (60) and the directional control valve (61) to change the path of the hydraulic fluid.
The positive limit (40) is positioned corresponding to the outside end of the piston rod (13) with a given distance that represents the proper position of the bottle (41) being moved. The bottle (41) is pushed by the outside end of the piston rod (13) to move until the bottle (41) abuts against the positive limit (40).
To operate the cylinder apparatus, only an appropriate pressure switch (20) has to be installed. When the hydraulic fluid flows into the protruding chamber (111) by the pump (60) continuously pumping, the pressure in the protruding chamber (111) will be instantly increased. However, the pressure in both the protruding chamber (111) and the retracting chamber (112) will be equalized. Therefore, a force proportional to the pressure in the protruding chamber (111) is produced and pushes the piston (12) toward the retracting chamber (112) to equalize the pressure in both chambers (111, 112). At the same time, the hydraulic fluid in the retracting chamber (111) flows out and the flow rate of the hydraulic fluid is controlled by the one-direction throttling valve (30) such that the piston (12) can smoothly move. Thus, the bottle (41) is pushed by the outside end of the piston rod (13) to move until the bottle (41) abuts the positive limit (40). For an instant, the pressure in the retracting chamber (112) will be decreased while the movement of the bottle (41) is stopped by the positive limit (40). The decrement of the pressure in the retracting chamber (112) will trigger the pressure switch (20) to send the electrical signal to the controlling host to stop pumping or changing the path of the hydraulic fluid. At this time, the piston rod (13) can be retracted, and the bottle (41) is pushed to the proper position, where a next process in a product line is prepared to handle the bottle (41), such as a sealing process for the bottle (41).
The pressure in the retracting chamber (112) is generally changed as the outside end of the piston rod (13) pushes the bottle (41) to abut the positive limit (40) each time. Therefore, the given distance between the positive limit (40) and an original position of the outside end of the piston rod (13) will represent a proper movement of the bottle (41). Consequently, the movement of the piston rod (13) will be equal to the given distance between the positive limit (40) and the original position of the outside end of the piston rod (13). Manufactures only have to adjust the positive limit (40) corresponding to the outside end of the piston rod (13). The object, such as the bottle (41) will always be pushed to abut the positive limit (40) with the proper position, where the sealing process deals with the bottle (41).
With reference to FIG. 3, an alternative embodiment of the invention has an additional feature that can be implemented with a one-direction throttling valve (30) and a pressure switch (20) connected to the pipes between the protruding chamber (111) and the directional control valve (61). In such a structure, when the outside end of the piston rod (13) pushes the bottle (41) against the positive limit (40), the pressure in the retracting chamber (112) will decrease and the pressure in the protruding chamber (111) will increase. Therefore, the controlling host can receive two electrical signals that are respectively sent out by the two pressure switches (20) that are respectively triggered by the changes of the pressure in the chambers (111, 112). The controlling host can compare with the two signals and take a suitable action to position the bottle (40) in an exact position each time. For instance, if the controlling host does not receive the signals sent out by both the pressure switches (20) at the same time, one of the pressure switches (20) may be broken down or working abnormally. The controlling host could stop the movement of the piston (12) and send out alarms to notify a repairman to check the pressure switches (20) to avoid any possible mistakes occurring.
The cylinder apparatus is very convenient to adjust. The pressure switch (20) can be installed and connected to the pipes at any conveniently and easily accessible position to make replacement of the pressure switch (20) convenient and easy. The pressure switches (20) are standard products in the hydraulic and pneumatic actuating industry, and a proper pressure switch (20) is conveniently selected to install. Also, the cylinder apparatus with a capability of detecting a piston position as described overcomes interference by spurious magnetic fields.
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, 11 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.

Claims

1. A cylinder apparatus with a capability of detecting piston position in a cylinder of a cylinder and the cylinder apparatus comprising:

a cylinder having

a closed tubular housing with a chamber defined in the closed tubular housing and adapted to connect to a pump with pipes;

a piston movably mounted in the chamber in the closed tubular housing and splitting the chamber into a retracting chamber and a protruding chamber; and

an actuating device coupled to the piston and adapted to selectively push and carry an object;

a positive limit positioned corresponding to the actuating device adapted to stop movement of the actuating device;

a first throttling valve selectively connected to the pipes between one of the retracting and the protruding chambers and the pump; and

a first pressure switch connected to the pipes between the first throttling valve and the chamber.

2. The cylinder apparatus as claimed in claim 1, wherein

the actuating device is a piston rod with an inside end and an outside end, the inside end of the piston rod attached to the piston in the closed tubular housing and the outside end of the piston rod extending out of the closed tubular housing and adapted to push the object to abut the positive limit.

3. The cylinder apparatus as claimed in claim 2, wherein

the first throttling valve is connected to the pipes between the retracting chamber in the closed tubular housing and the pump, and

the first pressure switch is connected to the pipes between the retracting chamber in the closed tubular housing and the first throttling valve.

4. The cylinder apparatus as claimed in claim 2, wherein

the first throttling valve is connected to the pipes between the protruding chamber in the closed tubular housing and the pump, and

the first pressure switch is connected to the pipes between the protruding chamber in the closed tubular housing and the first throttling valve.

5. The cylinder apparatus as claimed in claim 4, wherein

the cylinder apparatus further comprises

a second throttling valve connected to the pipes between the retracting chamber in the closed tubular housing and the pump, and

a second pressure switch connected to the pipes between the retracting chamber in the closed tubular housing and the second throttling valve.

6. The cylinder apparatus as claimed in claim 3, wherein the first throttling valve is one-directional.

7. The cylinder apparatus as claimed in claim 4, wherein the first throttling valve is one-directional.

8. The cylinder apparatus as claimed in claim 5, wherein both the first and the second throttling valves are one-directional.