Patent Application
20090056530
The present invention relates to a force amplifier, and more particularly, to a force amplifier utilizing a pressurized fluid.
Force amplifiers are commonly known and are typically employed in applications where human input force is inadequate. Alternatively, they are employed where human input may be adequate, but can become uncomfortable and/or unreliable under extended periods of time. One such application is with regard to the operation of a clutch in large commercial vehicles. In some circumstances a driver may be able to overcome the high clutch force, but repeated use can become uncomfortable to the driver and may result in premature fatigue. However, through the use of a force amplification system, the amount of force required of the driver can be substantially reduced, while the output force remains the same.
Typically, force amplifiers add additional force to an output using some pressurized fluid. The force amplifier converts the pressure supplied by the fluid into mechanical energy. The fluid can operate to multiply the force provided at the input to create a greater force at the output of the force amplifier.
Some of the prior art systems that attempt to provide adequate force amplification systems have numerous drawbacks. One such example is disclosed in U.S. Pat. No. 5,279,204 to Eugene. The power booster of Eugene suffers from a number of drawbacks. The complexity of the Eugene system results in increasing the force needed by a user in the event of a pressure failure. This is because the user must overcome a number of biasing members when applying a force on the input shaft before any movement of the output shaft is realized. This can amount in having a more negative effect in the absence of pressure than if the power booster were eliminated altogether. Furthermore, the input shaft is required to move a greater distance than reflected in the output shaft, i.e., the input distance is not in a 1:1 ratio with the output distance.
Another prior art system is disclosed in U.S. patent application 2004/0016618 to Burnell et al. The Burnell system requires a number of switches which transmits a clutch pedal position into an amount of boost required. Therefore, one module senses the tension by a user and a separate module provides the force amplification. This type of a system requires more space to function and results in an overly complex system.
The present invention overcomes these and other problems and an advance in the art is achieved.
A force amplifier is provided according to an embodiment of the invention. The force amplifier comprises a housing and a force assembly positioned in the housing. The force assembly includes an input force component, an output force component, and an intermediate force component. The intermediate force component rigidly couples the input force component to the output force component. The force amplifier further comprises an assist piston positioned in the housing. The assist piston is coupled to the force assembly. The force amplifier further comprises a regulating piston positioned in the housing. The regulating piston is coupled to the force assembly. The regulating piston controls the supply of a pressurized fluid acting on the assist piston.
A method for forming a force amplifier including a housing is provided according to an embodiment of the invention. The method comprises the steps of positioning a force assembly in the housing. The force assembly includes an input force component, an output force component, and an intermediate force component. The intermediate force component rigidly couples the input force component to the output force component. The method further comprises the step of positioning an assist piston in the housing. The method further comprises the step of coupling the assist piston to the force assembly. The method further comprises the steps of positioning a regulating piston in the housing. The method further comprises the step of coupling the regulating piston to the force assembly. The regulating piston controls the supply of a pressurized fluid acting on the assist piston.
A method for amplifying a force using a force amplifier is provided according to an embodiment of the invention. The method comprises the step of receiving a first force on a force assembly. The method further comprises the step of actuating a regulating piston with the first force. The regulating piston provides a pressurized fluid to an assist piston when the regulating piston is actuated. The method further comprises the step of generating a second force from the pressurized fluid acting on the assist piston. An output force of the force assembly comprises the first force plus the second force.
The housing 101 can be provided with a housing cap 106 at the input end. The housing cap 106 in some embodiments includes the aperture 104. The housing cap 106 can also close the input end of the force amplifier 100. The housing cap 106 can be attached to the housing using screws, adhesives, welding, brazing, or any other form of bonding known in the art.
The housing 101 can be provided with a protective boot 107. In some embodiments, the protective boot 107 comprises a rubber protective seal. However, the protective boot 107 can comprise other materials that would allow sufficient flexibility in order to allow the regulating piston 215 (described below) to move. The protective boot 107 can be provided to decrease the amount of dirt and debris that enters the housing 101. Additionally, the protective boot 107 can be provided to form a passageway for the fluid exhaust (described below).
The force amplifier 100 can communicate with a pressurized fluid supply (not shown). The fluid input 102 can accept the pressurized fluid from the supply and employ the pressurized fluid to amplify a force provided at the aperture 104 as described in more detail below. The pressurized fluid can comprise a pneumatic supply, hydraulic fluid, or other known fluids used in fluid-mechanic operations. It should be understood that the fluid can comprise either a gas or a liquid.
The pressurized fluid can be exhausted from the force amplifier 100 through the fluid exhaust 103. Although
The input aperture 104 is provided to accept an input force component (described below). Likewise, the output aperture 105 is provided to accept an output force component. Typically, the output force component is provided to perform some work on a work piece (not shown), while a user can directly or indirectly apply a force on the input force component. The force amplifier 100 can be provided in some embodiments to provide a force at the output that is greater than the force provided on the input force component.
The input 208 and output 209 components are coupled using an intermediate force component 210. According to an embodiment of the invention, the intermediate force component 210 provides a rigid connection between the input 208 and output 209 force components, i.e., the distance between the input 208 and the output 209 force component remains substantially constant. Additionally, the intermediate force component 210 provides a 1:1 ratio between the input 208 and output 209 force components with regard to force (in the absence of pressurized fluid).
The input 208 and output 209 force components are shown as cables in
In the embodiment shown, an assist piston 211 is coupled to the force assembly 250. According to one embodiment of the invention, the assist piston 211 is coupled to the input force component 208 and the intermediate force component 210. However, the assist piston 211 can be coupled to any of the components of the force assembly 250. The assist piston 211 includes piston seals 212 which form a substantially fluid tight seal with an assist piston chamber 213. The assist piston 211 can move along with the force assembly when a force is applied to the input force component 208. The assist piston 211 is shown coupled to the end of the input force component 208 and to the intermediate force component 210 using a nut 214. It should be understood however, that the assist piston 211 can be coupled to the force assembly in a number of different ways including, but not limited to, adhesives, welding, brazing, or some other manner of bonding. The assist piston 211 is provided to amplify the force that is provided on the input force component 208. The function of the assist piston 211 is discussed further below.
In the embodiment shown, a regulating piston 215 is coupled to the force assembly 250. According to the embodiment shown in
The regulating piston 215 can be provided with a regulating piston biasing member 217. In some embodiments, the regulating piston biasing member 217 can comprise a spring. However, it should be understood that other biasing members can be used. The regulating piston biasing member 217 is provided to at least partially counter the forces that the output force component conduit 216 delivers to the regulating piston 215.
The regulating piston 215 is also provided with one or more sealing members 218. The sealing member 218 provides a substantially fluid tight seal between the regulating piston 215 and the regulating piston chamber 219.
The regulating piston 215 can also be provided with the protective boot 107. The protective boot 107 can prevent or at least decrease the amount of dirt and debris that can pass into the aperture 105. As shown in
The force amplifier 100 can include a poppet chamber 220. In the embodiment shown in
As mentioned above, while the regulating piston 215 is shown as being coupled to the output force component 209 and the assist piston 211 is shown as being coupled to the input force component 208, it should be understood that the regulating piston 215 and the assist piston 211 could be coupled to any of the components of the force assembly 250. Furthermore, the terms ‘input’ and ‘output’ are relative and depend on whether the input force is provided as tension or compression.
As shown, the assist piston 211 has moved to the right along with the input force component 208. The tension provided on the force assembly 250 provides a compressive force on the regulating piston 215. The first force provided on the force assembly 250 is converted to the compressive force acting on the output force component conduit 216 using a mechanical conversion device generally known in the art. This compressive force is transferred to the regulating piston 215. When the compression provided is high enough, it overcomes the counter force provided by the regulating piston biasing member 217, causing the regulating piston 215 to move slightly to the right as shown in the figures.
As the regulating piston 215 moves to the right, the regulating exhaust seat 224 contacts the regulating poppet 221. Further movement overcomes the force of the regulating poppet biasing member 222 and the regulating piston 215, along with the poppet member 221, moves to the right. As the poppet member 221 is forced to the right, it breaks the seal created with the regulator supply seat 223. As shown in the figures, the regulating piston chamber 219 limits the movement of the regulating piston 215.
Once the seal between the poppet member 221 and the regulator supply seat 223 is broken, fluid is free to enter the gap 430 created between the poppet member 221 and the regulator supply seat 223. If pressurized fluid is provided through the fluid inlet 102, the pressure within the poppet chamber 220 will be greater than the pressure within the regulating piston chamber 219. Therefore, fluid will travel into the gap 430 and through the fluid supply passageway 327 and into the regulating piston chamber 219. Once fluid reaches the regulating piston chamber 219, it can also provide pressure on the assist piston 211 via the assist piston passageway 431. The pressure provided on the assist piston 211 provides a second force.
As pressure within the assist piston chamber 213 increases, the output force of the force assembly 250 comprises the first force and the second force of the pressurized fluid provided on the assist piston 211. The maximum amplification of the force delivered to the output force component 209 can be controlled by the pressure of the fluid being supplied to the force amplifier 100 through the fluid input 102. The amplification force can alternatively or additionally be controlled by the size of the assist piston 211. By changing the cross sectional area of the assist piston 211, the amount of force provided by the pressurized fluid can be controlled for the particular application.
The pressure within the regulating piston chamber 219 provided by the fluid can at least partially counter the compression caused by the output force component conduit 216. This takes some of the pressure off from the regulator supply seat 223 caused by contact between the regulating piston 215 and the regulator supply seat 223.
When the force provided on the input force component 208 is held substantially constant, the assist piston 211 is still amplifying the force provided on the output force component 209. This can be advantageous, for example, when a user is holding the input force component 208 in a substantially constant position for an extended period of time.
As described above, the force amplifier 100 provides a number of advantages. With a pressurized fluid provided at the fluid input, the force amplifier 100 can deliver a greater force at the output of the force assembly 250 than provided on the input of the force assembly 250. Furthermore, the assist piston 211 is actuated simply by a force being applied to the input force component 208. Because the regulating piston 215 responds to a force on the force assembly 250, the force provided by the input force component 208 can control the fluid flow to the assist piston 211.
The force amplifier 100 can advantageously operate in the absence of some external power supply. Additionally, in the event of a loss of fluid pressure, a user can still provide an output force. Because the input force component 208 and the output force component 209 can be rigidly coupled to one another, a user's force applied to the input force component 208 still produces a response on the output force component 209. The only difference is that in the absence of fluid supply, the force delivered to the output force component 209 is in a 1:1 ratio with the force provided on the input force component 208. However, because the intermediate force component 210 couples the input force component 208 to the output force component 209 in a rigid manner, i.e., the distance between the input 208 and output 209 components remain substantially constant, the stroke is also in a 1:1 ratio. Therefore, if the fluid pressure is suddenly lost, the stroke of the input force component 208 does not change. Consequently, in the absence of fluid pressure, a user can still safely provide force to the output force component 209.
The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the invention. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the invention. It will also be apparent to those of ordinary skill in the art that the above-described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the invention.
Thus, although specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. The teachings provided herein can be applied to other force amplifiers, and not just to the embodiments described above and shown in the accompanying figures. Accordingly, the scope of the invention should be determined from the following claims.
