Patent Application
20150226064
1. Technical Field
The present invention relates generally to power control apparatuses and, more particularly, to a power control apparatus which uses hydraulic pressure and is able to control the magnitude of force required to operate it.
2. Description of the Related Art
Generally, exercise machines for weight training are configured such that weight stacks that are weight bodies are selectively connected to a cable provided with a handle so that a variable load can be applied to an exerciser.
That is, to do exercise using such an exercise machine, the exerciser connects some of the weight stacks, each of which has a predetermined weight (e.g., 5 kg or 10 kg), to one end of the cable such that a desired amount of load is applied, grasps the handle connected to the other end of the cable, and then pulls or lifts it.
However, such a cable type exercise machine for weight training is disadvantageous in that because the exerciser does exercise in such a way that some selected from among the weight stacks are used, the magnitude of a load the exerciser wants cannot be finely adjusted.
In an effort to overcome the above-mentioned disadvantage, a load control apparatus which uses a hydraulic cylinder to finely adjust the magnitude of a load was proposed.
As shown in
Furthermore, defined in the cylinder body 1a and partitioned by the piston 1b, the two hydraulic chambers are connected to each other by a connection pipe 2. A valve 3 is provided on the connection pipe 2. Having the above-mentioned construction, the load control apparatus using the hydraulic cylinder 1 is operated by a principle in which force required to move the piston 1b is controlled by adjusting the degree of opening of the connection pipe 2 using the valve 3.
In other words, if the degree of opening of the connection pipe 2 is increased, hydraulic pressure needed to flow fluid from one hydraulic chamber into the other hydraulic chamber is reduced, whereby force required to move the piston 1b is also reduced.
If the degree of opening of the connection pipe 2 is reduced, hydraulic pressure needed to flow fluid from one hydraulic chamber into the other hydraulic chamber is increased. As a result, force required to move the piston 1b is also increased.
However, in the conventional load control apparatus, when the piston 1b moves, rates of change in volume of the two hydraulic chambers differ from each other because of the piston rod 1c which protrudes from one side of the piston 1b. Therefore, the two hydraulic chambers cannot be directly connected to each other by the connection pipe 2, and a separate hydraulic tank 4 which is connected to the two hydraulic chambers is required.
Therefore, the conventional load control apparatus is problematic in that space required for installation of the apparatus is increased because the separate hydraulic tank 4 which is connected to the two hydraulic chambers formed in the hydraulic cylinder 1 is required to control both a rate at which fluid is discharged from one hydraulic chamber and a rate at which fluid is supplied into the other hydraulic chamber.
Furthermore, in the conventional load control apparatus, because of the fact that after a rate at which fluid is discharged from one hydraulic chamber of the hydraulic cylinder 1 is controlled by the hydraulic tank 4 the fluid must be supplied into the other hydraulic chamber, the apparatus may frequently malfunction, and a separate control structure to control the discharge rate of fluid and the inflow rate of fluid is required, thus making the design of the apparatus complex.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a power control apparatus which is configured such that two hydraulic chambers of a cylinder can be directly connected to each other, thus simplifying the operation structure thereof.
In order to accomplish the above object, the present invention provides a power control apparatus, including: a cylinder body unit defining a hydraulic chamber therein; a piston moving along an inner surface of the hydraulic chamber of the cylinder body unit, the piston partitioning the hydraulic chamber into a first hydraulic chamber and a second hydraulic chamber; a screw shaft unit rotatably disposed in the hydraulic chamber of the cylinder body unit, the screw shaft unit passing through the piston and being threadedly coupled to the piston; a hydraulic chamber connection pipe connecting the first hydraulic chamber to the second hydraulic chamber that is partitioned from the first hydraulic chamber by the piston; and a valve unit provided on the hydraulic chamber connection pipe, the valve unit controlling opening of a passage of the hydraulic chamber connection pipe.
A rate of change in volume of the first hydraulic chamber in response to movement of the piston may be equal to a rate of change in volume of the second hydraulic chamber.
Extension shafts may protrude from respective opposite ends of the screw shaft unit and be rotatably coupled to the cylinder body unit, one of the extension shafts protruding out of the cylinder body unit. The power control apparatus may further include a power transmission unit connected to one of the extension shafts of the screw shaft unit.
The power transmission unit may include: a rotating gear coupled to the corresponding extension shaft; and a plurality of transmission gears engaging with the rotating gear to transmit an operating force of an exerciser to the rotating gear.
The power transmission unit may further include a clutch unit selectively engaging the transmission gears with each other so that the operating force of the exerciser can be controlled in steps.
The power control apparatus may further include a guide bar disposed in the hydraulic chamber in a direction in which the piston moves, the guide bar passing through the piston and guiding linear movement of the piston.
The power control apparatus may further include a control unit controlling a degree of opening of the valve unit, the control unit including: a controller connected to the valve unit, the controller controlling operation of the valve unit; an operation panel connected to the controller; a first hydraulic sensor connected to the controller, the first hydraulic sensor measuring a hydraulic pressure in the first hydraulic chamber; and a second hydraulic sensor connected to the controller, the second hydraulic sensor measuring a hydraulic pressure in the second hydraulic chamber.
The piston may have a hydraulic chamber connection hole therein, the hydraulic chamber connection hole communicating the first hydraulic chamber with the second hydraulic chamber. The power control apparatus may further include a valve diaphragm closing the hydraulic chamber connection hole when the piston moves in one direction and opening the hydraulic chamber connection hole when the piston moves in the other direction.
The valve diaphragm may comprise a plate spring having a predetermined elasticity.
The power control apparatus may further include: an auxiliary connection pipe connecting the first hydraulic chamber to the second hydraulic chamber; and a check valve provided on the auxiliary connection pipe, the check valve controlling flow of fluid such that the fluid flows through the auxiliary connection pipe only in one direction.
The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.
Reference now should be made to the drawings, throughout which the same reference numerals are used to designate the same or similar components.
As shown in
It is preferable that the cylinder body unit 10 have a cylindrical shape. The cylinder body unit 10 is configured such that the hydraulic chamber 11 formed therein is sealed.
The cylinder body unit 10 includes a cylinder body 10a and covers 10b which respectively cover opposite ends of the cylinder body 10a to seal the hydraulic chamber 11 formed in the cylinder body 10a.
A piston 20 is disposed in the cylinder body unit 10 so as to be movable along an inner surface of the hydraulic chamber 11 and partitions the hydraulic chamber 11 into a first hydraulic chamber 11a and a second hydraulic chamber 11b.
Preferably, an O-ring 20a is provided on an outer circumferential surface of the piston 20 and is brought into close contact with the inner surface of the hydraulic chamber 11 so as to seal the first hydraulic chamber 11a and the second hydraulic chamber 11b from each other.
Each of the first and second hydraulic chambers 11a and 11b of the cylinder body unit 10 is filled with fluid. As well as gas such as air and liquid such as oil, any material can be used as the fluid so long as it can generate hydraulic pressure.
A first inlet/outlet port 11c and a second inlet/outlet port 11d are respectively provided on the opposite ends of the cylinder body unit 10. The first inlet/outlet port 11c connects the first hydraulic chamber 11a to a hydraulic chamber connection pipe 40 which will be explained later herein. The second inlet/outlet port 11d connects the second hydraulic chamber 11b to the hydraulic chamber connection pipe 40.
The O-ring 20a seals between the outer circumferential surface of the piston 20 and the inner surface of the cylinder body unit 10 so as to seal between the first and second hydraulic chambers 11a and 11b that are partitioned from each other by the piston 20. Thereby, fluid can reliably and smoothly flow through the first and second inlet/outlet ports 11c and 11d.
Passing through the piston 20, a screw shaft unit 30 is rotatably provided in the hydraulic chamber 11 of the cylinder body unit 10 and is threadedly coupled to the piston 20.
Opposite ends of the screw shaft unit 30 are rotatably connected to the respective covers 10b that seal the opposite ends of the cylinder body unit 10.
The screw shaft unit 30 passes through a central portion of the piston 20 in the cylinder body unit 10 and is oriented in the longitudinal direction of the cylinder body unit 10 so that the piston 20 can move along the screw shaft unit 30 in such a way that a rate of change in the volume of the first hydraulic chamber 11a in response to the movement of the piston 20 corresponds to that of the second hydraulic chamber 11b.
Protruding from the respective opposite ends of the screw shaft unit 30, extension shafts 31 are rotatably coupled to the respective covers 10b.
The power control apparatus according to the present invention further includes a power transmission unit 60 which is connected to one of the extension shafts 31 of the screw shaft unit 30.
The power transmission unit 60 receives operating force from an exerciser and rotates the screw shaft unit 30 using the operating force.
One of the extension shafts 31 of the screw shaft unit 30 passes through the corresponding cover 10b and protrudes out of it. The power transmission unit 60 includes a rotating gear 61 which is coupled to the extension shaft 31 that protrudes out of the cover 10b, and a plurality of transmission gears 62 which engage with the rotating gear 61 to transmit operating force to the rotating gear 61.
To make rotation of the screw shaft unit 30 smooth and ensure the sealed state of the hydraulic chamber 11, the screw shaft unit 30 preferably includes bearings 31a which are provided on the respective extension shafts 31, and a sealing member 31b which seals a shaft hole through which the corresponding extension shaft 31 passes.
Using a gear ratio between the rotating gear 61 and the transmission gears 62 that transmit power to the rotating gear 61, the power transmission unit 60 can adjust force, that is, operating force of the exerciser, required to operate the apparatus.
The power transmission unit 60 further includes a clutch unit 63 which controls required operating force of the exerciser by steps in such a way that the transmission gears 62 selectively engage with each other.
The construction and operation of the clutch unit 63 can be easily embodied from those of a known clutch unit, so further explanation thereof will be omitted.
The first hydraulic chamber 11a and the second hydraulic chamber 11b are directly connected to each other by the hydraulic chamber connection pipe 40 so that when the piston 20 moves, fluid discharged from one of the first and second hydraulic chambers 11a and 11b is directly drawn into the other one.
A first end of the hydraulic chamber connection pipe 40 is connected to the first inlet/outlet port 11c, and a second end thereof is connected to the second inlet/outlet port 11d. A valve unit 50 is provided at a predetermined position on the hydraulic chamber connection pipe 40 so as to control a passage of the pipe.
The valve unit 50 opens or closes the passage of the hydraulic chamber connection pipe 40 and adjusts the degree of opening of the passage to control the flow of fluid between the first and second hydraulic chambers 11a and 11b and hydraulic pressure required for the flow of fluid.
For instance, when the passage of the hydraulic chamber connection pipe 40 completely opens, the piston 20 can be moved in the hydraulic chamber 11 even by a very low pressure. Therefore, only small operating force is required to rotate the screw shaft unit 30.
As the degree of opening of the passage of the hydraulic chamber connection pipe 40 is reduced, force to move the piston 20 in the hydraulic chamber 11 is increased, so that operating force required to rotate the screw shaft unit 30 is also increased.
Therefore, the magnitude of operating force, with which the exerciser rotates the screw shaft unit 30 and moves the piston 20, can be finely controlled by adjusting the degree of opening of the passage of the hydraulic chamber connection pipe 40 using the valve unit 50.
Furthermore, in the present invention, the magnitude of operating force required to move the piston 20 can be more finely controlled by adjusting the gear ratio using the clutch unit 63 as well as adjusting the degree of opening of the passage of the hydraulic chamber connection pipe 40 using the valve unit 50.
Further, a rate of change in the volume of the first hydraulic chamber 11a when the piston 20 moves is the same as that of the second hydraulic chamber 11b, and fluid discharge from one of the first and second hydraulic chambers 11a and 11b is directly drawn into the other one through the hydraulic chamber connection pipe 40. Hence, a separate device for controlling fluid discharge rates and fluid inflow rates of the first and second hydraulic chambers 11a and 11b is not required.
The power control apparatus according to the present invention further includes a guide bar 70 which is disposed in the hydraulic chamber in a direction in which the piston 20 moves. The guide bar 70 passes through the piston 20 and guides linear movement of the piston 20.
In detail, the guide bar 70 which passes through the piston 20 is fixed to the covers 10b provided on the opposite ends of the cylinder body unit 10. Preferably, a plurality of guide bars 70 are provided in the hydraulic chamber 11 so as to more reliably guide the linear movement of the piston 20.
Each guide bar 70 which passes through the piston 20 has a constant volume per length in the first hydraulic chamber 11a and the second hydraulic chamber 11b so that a rate of change in the volume of each of the first and second hydraulic chambers 11a and 11b in response to movement of the piston 20 can be maintained constant.
The power control apparatus according to the present invention further includes a control unit which controls the degree of opening of the valve unit 50. The control unit 80 includes a controller 81 which is connected to the valve unit 50 so as to control the operation of the valve unit 50, and an operation panel 82 which is connected to the controller 81.
The control unit 80 further includes a first hydraulic sensor 83 which is connected to the controller 81 and measures the hydraulic pressure in the first hydraulic chamber 11a, and a second hydraulic sensor 84 which is connected to the controller 81 and measures the hydraulic pressure in the second hydraulic chamber 11b.
The operation panel 82 includes operation buttons which are manipulated by a user, that is, the exerciser, and a display panel which enables checking of the operation conditions.
Each of the first hydraulic sensor 83 and the second hydraulic sensor 84 transmits a signal that pertains to the pressure of the corresponding hydraulic chamber 11a or 11b to the controller 81.
The controller 81 controls the valve unit 50 in response to an order of the exerciser using the operation buttons of the operation panel 82 and adjusts the degree of opening of the passage of the hydraulic chamber connection pipe 40, thus controlling the operating force by which the piston 20 is moved.
The exerciser can use the display panel of the operation panel 82 to check the magnitude of the operating force and can easily control the magnitude depending on operation conditions of the apparatus.
As shown in
Preferably, the power control apparatus according to the present invention further includes a valve diaphragm 90 which closes the hydraulic chamber connection hole 21 when the piston 20 moves in one direction and opens the hydraulic chamber connection hole 21 when the piston 20 moves in the other direction.
The valve diaphragm 90 is an elastic plate spring and is fixed only at an end thereof to one of opposite sides of a portion of the piston 20 that defines the hydraulic chamber connection hole 21.
As shown in
As such, to move the piston 20 in the direction corresponding to the side at which the valve diaphragm 90 is installed, the exerciser must apply operating force the magnitude of which has been adjusted by the valve unit 50 thereto.
On the other hand, as shown in
That is, to move piston 20 in the direction opposite to the side at which the valve diaphragm 90 is installed, the exerciser has only to apply force that is much smaller than the operating force the magnitude of which has been adjusted by the valve unit 50.
Using the above-mentioned principle, force required to return the piston 20 to its original position after the exerciser applies operating force to the apparatus to do exercise can be greatly reduced. Therefore, it becomes easy to design an exercise machine which is used in such a way that an exerciser repeats a specific motion.
The number of hydraulic chamber connection holes 21, the size of each hole and the elastic force of each valve diaphragm 90, that is, the magnitude of hydraulic pressure by which the valve diaphragm 90 is opened, may be changed to individually control the magnitudes of operating forces required to rotate the screw shaft unit 30 in the normal direction and the reverse direction, thereby allowing the design of a diverse variety of exercise machines.
The power control apparatus according to the present invention may further include an auxiliary connection pipe 100 which connects the first hydraulic chamber 11a to the second hydraulic chamber 11b, and a check valve 110 which is provided on the auxiliary connection pipe 100 to control the flow of fluid such that the fluid flows through the auxiliary connection pipe 100 only in one direction.
In the following example, although the check valve 110 will be explained as being configured such that fluid flows only in a direction from the first hydraulic chamber 11a to the second hydraulic chamber 11b, it may be modified as being designed such that fluid flows only in a direction from the second hydraulic chamber 11b to the first hydraulic chamber 11a in direct opposition to that of the following example. The operation principle of the modification is the same as that of the origin.
That is, when the piston 20 moves to compress the second hydraulic chamber 11b, fluid that has been in the second hydraulic chamber 11b can move only through the hydraulic chamber connection pipe 40.
Therefore, to move the piston 20 in the direction in which the second hydraulic chamber 11b is compressed, the exerciser has to apply operating force the magnitude of which has been adjusted by the valve unit 50.
On the other hand, when the piston 20 moves to compress the first hydraulic chamber 11a, fluid that has been in the first hydraulic chamber 11a can move to the second hydraulic chamber 11b not only through the hydraulic chamber connection pipe 40 but also through the auxiliary connection pipe 100 provided with the check valve 110.
Therefore, the exerciser can move the piston 20 in the direction, in which the first hydraulic chamber 11a is compressed, even using force that is much smaller than the operating force the magnitude of which has been adjusted by the valve unit 50.
Furthermore, the magnitude of operating force required to move the piston 20 in the direction in which the first hydraulic chamber 11a is compressed can be controlled by adjusting the degree of opening of a passage of the auxiliary connection pipe 100 using the check valve 110.
As described above, a power control apparatus according to the present invention has a simple structure, so that the production cost thereof is low. In addition, the power control apparatus can be used even in comparatively small space.
Furthermore, the present invention makes it possible to finely adjust operating force required to operate it and further diversify the kinds of exercise machines that can be designed, thus meeting requirements of exercisers.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
