Technical Field

The present disclosure relates generally to valve devices for controlling hydraulic fluid flow.

Background

A number of different types of beds, for example hospital beds, are designed to be raised and lowered. For example, hospital beds may be designed to raise and lower in a straight configuration and/or one or more parts of the bed may incline and recline. One particular example is the bed of an MRI (magnetic resonance imaging) machine. Such beds are designed to move in and out of the MRI circular magnet and are designed to raise and lower. Typically, hydraulic cylinders are incorporated into MRI beds to allow for the raising and lowering. It is desirable for such hydraulic cylinders to be controlled by low-leak valve devices.

Summary

One aspect of the present disclosure relates to a valve device for controlling fluid flow to and from a hydraulic actuator such as a hydraulic cylinder. In one example, the hydraulic actuator may be a hydraulic cylinder used to control movement of a bed such as the bed of an MRI machine. In certain examples, the actuator is a single acting cylinder. While hydraulic cylinders for actuating beds are one particular type of actuator for which valve devices in accordance with the principles of the present disclosure can be used, it will be appreciated that valve devices in accordance with the principles of the present disclosure can be used with other types of actuators as well.

One aspect of the present disclosure relates to a valve device having a relatively low number of parts, and a compact configuration allowing for a reduced size valve package. Another aspect of the present disclosure relates to a valve device having a relatively low number of parts thereby reducing assembly and manufacturing costs. A low number of parts also can enhance reliability and/or serviceability of the valve device.

A further aspect of the present disclosure relates to a valve assembly having a low-leak configuration.

Still another aspect of the present disclosure relates to a valve device having in-line valves (e.g., one-way type check-valves having valve members that are spring-biased to closed positions in which the valve members engage valve seats and that are moveable to open positions by displacing the valve members from the valve seats against the spring bias) in which a spring or springs positioned axially between the valve members biases the check valves to the closed positions. In one example, the inline valves share a common spring. In one example, one of the valves can be opened by a mechanical actuator such as a manual actuator that can be engaged by an operator.

A further aspect of the present disclosure relates to a valve device including a manifold defining a pump port, a tank port, and a hydraulic actuator port. The valve device also includes a valve body mounted within a bore of the manifold. The valve body contains two valves. In one example, valves can be arranged in an inline configuration. One of the valves can include a one-way check valve that allows hydraulic fluid to flow from the pump port through the valve body to the hydraulic actuator port, and that prevents hydraulic fluid from flowing from the hydraulic actuator port through the valve body to the pump port. The other valve is spring biased to a closed position in which hydraulic fluid is prevented from flowing from the hydraulic actuator port to the tank port. A mechanical actuator can be provided for allowing the other valve to be moved against the spring bias (e.g., through manual actuation) from the closed position to an open position where fluid can flow from the hydraulic actuator port to the tank port. In certain examples, a filter can be carried with the valve body to prevent contaminants from reaching the hydraulic actuator port. In certain examples, the filter can include a filter screen that at least partially circumferentially surrounds the valve body. In certain examples, the valve body can define an orifice or orifices for controlling hydraulic fluid flow to and from the actuator port.

A further aspect of the present disclosure relates to valves configured to provide low leakage. In certain examples, the valves can include valve seats defining valve openings, and valve members movable relative to the valve seats between open positions where flow is permitted through the valve openings and closed positions where the valve members contact the valve seats to block flow through the valve openings. In certain examples, the valve seats and the valve members are made of different materials having different hardness levels selected to enhance sealing and prevent leakage through the valve openings when the valve members are in the closed positions. In one example, one of the valve seat and the valve member can include a metal construction and the other of the valve seat and the valve member can include a polymeric construction. In one example, the metal construction and the polymeric construction are both non-magnetic. In certain examples, the metal construction can include stainless steel, such as 440C stainless steel. In certain examples, polymeric construction can include a fiber reinforced plastic. In one example, the fiber reinforced plastic can include a carbon fiber reinforced plastic. In another example, the polymeric material can include PolyEtlierEtlierKetone (PEEK) reinforced by carbon fiber. In one example, the PEEK material can include 20-40% carbon fiber reinforcement, or most preferably about 30% carbon fiber reinforcement.

Still another aspect of the present disclosure relates to a valve device including a manifold defining a pump port, a tank port, and a hydraulic actuator port. The valve device also includes a valve body mounted within the manifold. The valve body defines a valve axis that extends through an interior of the valve body. The interior of the valve body is in fluid communication with the hydraulic actuator port. The valve body defines first and second valve seats aligned along the valve axis. The first valve seat defines a first valve opening for providing fluid communication between the interior of the valve body and the pump port. The second valve seat defines a second valve opening for providing fluid communication between the interior of the valve body and the tank port. The valve device further includes a first valve member positioned at least partially within the interior of the valve body for opening and closing the first valve opening. The first valve member is movable relative to the valve body along the valve axis between an open position where fluid communication is provided between the interior of the valve body and the pump port and a closed position where the valve member contacts the first valve seat to block fluid communication between the interior of the valve body and the pump port. The valve device further includes a second valve member positioned at least partially within the interior of the valve body for opening and closing the second valve opening. The second member is movable relative to the valve body along the valve axis between an open position where fluid communication is provided between the interior of the valve body and the tank port and a closed position where the second valve member contacts the second valve seat to block fluid communication between the interior of the valve body and the tank port. The valve device additionally includes a spring or springs positioned within the interior of the valve body axially between the first and second valve members for biasing the first and second valve members toward the closed positions. Additionally, the valve device includes a mechanical actuator mounted within the manifold for moving the second valve member from the closed position to the open position.

A variety of additional aspects will be set forth in the description that follows. The aspects can relate to individual features and to combinations of features. It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the examples disclosed herein are based.

Brief Description of the Drawings

The accompanying drawings, which are incorporated in and constitute a part of the speci fication, illustrate aspects of the present disclosure and together with the description, serve to explain the principles of the disclosure. A brief description of the drawings is as follows:

Figure 1 is a schematic view of a valve device in accordance with the principles of the present disclosure shown interfacing with a hydraulic actuator; Figure 2 is a more detailed view of the valve device of Figure 1 , showing a valve assembly of the valve device mounted within a valve manifold of the valve device;

Figure 3 shows the valve assembly of Figure 2 in isolation from the valve manifold;

Figure 3A is a detailed view of a portion of Figure 3;

Figure 3B is a detailed view of a portion of another example valve assembly similar to the valve assembly of Figure 3 except that the filter/screen is disposed within the valve body;

Figure 4 illustrates another valve device in accordance with the principles of the present disclosure;

Figure 4 A is an enlarged view of a portion of Figure 4;

Figure 5 depicts a further valve device in accordance with the principles of the present disclosure; and

Figure 6 depicts still another valve device in accordance with the principles of the present disclosure.

Detailed Description

Figure 1 illustrates a system 20 in accordance with the principles of the present disclosure. The system 20 includes an actuator 22 that interfaces with a valve device 24 in accordance with the principles of the present disclosure. In one example, the actuator 22 is a hydraulic cylinder, such as a single-acting hydraulic cylinder. In one example, the actuator 22 can be used to control movement of a bed, such as a bed for an MRI machine. In one example, the valve device 24 can be configured as an end cap (e.g., a cylinder end cap) that mounts to one end of the actuator 22.

Referring still to Figure 1 , the valve device 24 includes a valve manifold 26 defining a pump port 28 adapted for connection to a source of pressurized hydraulic fluid such as a pump 30, a tank port 32 adapted for connection to a tank 33 (e.g., a reservoir), and a hydraulic actuator port 34 adapted for connection to the actuator 22. The valve device 24 also includes a valve assembly 36 that mounts within the valve manifold 26. The valve assembly 36 includes a first valve 38 and a second valve 40.

In one example, the first and second valves 38, 40 are arranged in an inline configuration. In one example, the first and second valves 38, 40 are each movable between an open position and a closed position.

The first valve 38 can be a check valve that is biased toward the closed position. The check valve 38 prevents hydraulic fluid from flowing through the valve assembly 36 from the hydraulic actuator port 34 to the pump port 28. The first valve 38 allows hydraulic fluid to flow from the pump port 28 through the valve assembly 36 to the hydraulic actuator port 34 when a spring bias of the valve is overcome. For example, when the pump 30 is activated, pressurized fluid from the pump 30 overcomes the spring bias holding the first valve 38 in the closed position, thereby causing the first valve 38 to move to the open position such that fluid can flow from the pump port 28 through the valve assembly 36 to the hydraulic actuator port 34.

The second valve 40 also can have a check-valve type configuration and can be spring biased toward the closed position. In the closed position, the second valve 40 prevents hydraulic fluid from flowing between the hydraulic actuator port 34 and the tank port 32. For example, with the second valve 40 closed, hydraulic fluid is prevented from flowing from the hydraulic actuator port 34 through the valve assembly 36 to the tank port 32.

The valve device 24 further includes a mechanical actuator 42 that can be used (e.g., manually actuated) to move the second valve 40 from the closed position to the open position. When actuated, the mechanical actuator 42 overcomes the spring bias holding the second valve 40 in the closed position to move the second valve 40 to the open position. In the open position, hydraulic fluid can flow from the hydraulic actuator port 34 through the valve assembly 36 to the tank port 32. The mechanical actuator 42 can be mechanically coupled to a manual actuation device, such as a foot pedal.

The valve assembly 36 can include one or more orifices 43 for providing smooth, controlled fluid flow between the actuator 22 and the valve assembly 36. In a preferred example, the orifice or orifices 43 each have a fixed size selected to provide a smooth, controlled flow rate. In other examples, the orifice or orifices 43 can have variable sizes to provide adjustable flow rates through the valve assembly 36. In the examples shown in Figures 1 , 5, and 6, the valve assemblies 36, 236, 336 include a single orifice 43, 284. In the examples shown in Figures 2-4, the valve assemblies 36, 136 include two orifices 84, 86.

The valve assembly 36 further can include one or more filters 44 for filtering hydraulic fluid to prevent contaminants from reaching the actuator 22. In the example shown in Figure 1 , the valve assembly 36 includes two filters 44. A first of the filters 44 is disposed between the pump port 28 and the first valve 38. The second of the filters 44 is disposed between the orifice 43 and the hydraulic actuator port 34. In other examples, a single filter 98 may be disposed between the orifices 43, 84, 86 and the hydraulic actuator port 34 (see Figure 3).

As indicated above, the actuator 22 can be a hydraulic cylinder used to raise and lower a bed, such as a bed for an MRI machine. When it is desired to raise the bed, the pump 30 is activated, which causes hydraulic fluid to flow from the pump 30 through the valve assembly 36 (e.g., through the valve 38) to the actuator 22, thereby raising the bed. When the bed reaches the desired level, the pump 30 is deactivated and the valve assembly 36 effectively holds the bed at the desired elevation via the closed valves 38, 40. When it is desired to lower the bed, the second valve 40 is opened by actuating the mechanical actuator 42. With the second valve 40 open, fluid from the hydraulic actuator 22 is forced through the valve assembly 36 to tank 33, thereby allowing the bed to be lowered. It will be appreciated that gravity acting on the actuator 22 (e.g., from the weight of the bed and/or the weight of a person on the bed) can force the hydraulic fluid to flow through the valve assembly 36. It will be appreciated that the size of the orifice 43 limits or controls the speed that the bed is raised or lowered by the actuator 22.

Referring to Figure 2, the valve assembly 36 can include a valve body 50 mounted in a bore 52 of the valve manifold 26. The valve body 50 defines a valve axis 54 that extends through an interior 56 of the valve body 50. The interior 56 of the valve body 50 is in fluid communication with the hydraulic actuator port 34. Thus, the interior 56 of the valve body 50 is in fluid communication with the actuator 22. The valve body 50 defines first and second valve seats 58, 60 aligned along the valve axis 54 respectively corresponding to the first and second valves 38, 40. The first valve seat 58 defines a first valve opening 62 for providing fluid communication between the interior 56 of the valve body 50 and the pump port 28. The second valve seat 60 defines a second valve opening 64 for providing fluid communication between the interior 56 of the valve body 50 and the tank port 32.

The first valve 38 of the valve assembly 36 also includes a first valve member 66 positioned at least partially within the interior 56 of the valve body 50 for opening and closing the first valve opening 62. First valve member 66 is movable relative to the valve body 50 along the valve axis 54 between an open position where fluid communication is provided between the interior 56 of the valve body 50 and the pump port 28 and a closed position where the first valve member 66 contacts the first valve seat 58 to block fluid communication between the interior 56 of the valve body 50 and the pump port 28. In one example, the first valve member 66 is a ball that makes circular line contact with the first valve seat 58 when in the closed position.

The second valve 40 of the valve assembly 36 includes a second valve member 68 positioned at least partially within the interior 56 of the valve body 50 for opening and closing the second valve opening 64. The second valve member 68 is movable relative to the valve body 50 along the valve axis 54 between an open position and a closed position. When the second valve member 68 is in the open position, fluid communication is provided between the interior 56 of the valve body 50 and the tank port 32. When the second valve member 68 is in the closed position, the second valve member 68 contacts the second valve seat 60 to block fluid communication between the interior 56 of the valve body 50 and the tank port 32. In one example, the second valve member 68 can include a poppet member.

The poppet member 68 can include an angled portion 70 (see Figure 3A) adapted to make circular line contact with the second valve seat 60 when the second valve member 68 is in the closed position. The poppet member also can include an elongate stem 72 that extends outwardly through the second valve opening 64. The elongate stem 72 can be engaged by the mechanical actuator 42 to move the second valve member 68 from the closed position to the open position. The mechanical actuator 42 and the elongated stem 72 can extend through a tank passage 74 defined by the valve manifold 26. The tank passage 74 can extend from the tank port 32 to the second valve opening 64. In the example shown in Figure 2, the mechanical actuator 42 engages the elongate stem 72 (via a section not visible in the cross-section displayed in Figure 2).

The poppet member 68 also can include an interior piston portion 76 positioned within the interior 56 of the valve body 50. The interior piston portion 76 divides the interior 56 of the valve body 50 into a first region 56a and a second region 56b (see Figure 3). The first region 56a is located axially between the piston portion 76 and the first valve seat 58 and the second region 56b is axially between the piston portion 76 and the second valve seat 60. It will be appreciated that the interior piston portion 76 reciprocates along the valve axis 54 within the interior 56 as the second valve member 68 is moved back and forth between the open and closed positions. Thus, the sizes of the first and second interior regions 56a, 56b vary depending upon the position of the second valve member 68.

The valve device 24 additionally includes a spring 78 or springs positioned within the interior 56 of the valve body 50. The spring 78 or springs can be configured to bias the first and second valve members 66, 68 toward their

corresponding closed positions. In a preferred example, a single spring 78 is used to bias both of the first and second valve members 66, 68 toward their closed positions. In one example, the single spring 78 can include a coil spring. In one example, one end of the spring 78 is received within a pocket 80 defined by the piston portion 76 of the second valve member 68 and the other end engages the spherical surface of the ball forming the first vah'e member 66.

In one example, the valve body 50 defines a first orifice 84 and a second orifice 86. The first orifice 84 provides fluid communication between the first region 56a of the interior portion 56 of the valve body 50 and the hydraulic actuator port 34. The second orifice 86 provides fluid communication between the second region 56b of the interior portion 56 of the valve body 50 and the hydraulic actuator port 34. It will be appreciated that when the first valve member 66 is in the open position, the first valve opening 62 provides fluid communication between the first interior region 56a and the pump port 28. Additionally, when the second valve member 68 is in the open position, the second valve opening 64 provides fluid communication between the second interior region 56b and the tank port 32. The piston portion 76 of the second valve member 68 isolates the first interior region 56a from the second interior region 56b. Accordingly, the piston portion 76 isolates the first orifice 84 from the second interior region 56b and isolates the second orifice 86 from the first interior region 56a.

When it is desired to extend the actuator 22, the pump 30 is activated, thereby causing fluid to flow through the first valve opening 62, through the first orifice 84, and through the port 34 to the actuator 22 to cause extension of the actuator 22. When it is desired to retract the actuator 22, the second valve member 68 is moved to the open position by the mechanical actuator 42 while the pump 30 is inactive, thereby causing hydraulic fluid to flow from the actuator 22, through the port 34, through the second orifice 86, and through the second valve opening 64 to tank 33.

In certain examples, the valve body 50 can include at least first and second pieces 50a, 50b between which the spring 78 and the valve members 66, 68 are captured. The first and second pieces 50a, 50b can be compressed axially together within the bore 52 by a plug 90. In one example, the plug 90 is threaded into a port 92 defined by the valve manifold 26. In other examples, the plug 90 is welded, bonded, or otherwise coupled to the valve body 50 or a portion thereof. The valve manifold 26 and the plug 90 can cooperate to define a pump flow passage 94 that extends from pump port 28 to the first valve opening 62. The manifold 26 also can define an actuator passage 96 that extends from the hydraulic actuator port 34 to the first and second orifices 84, 86. The valve body 50 can be recessed about its exterior in a central region corresponding to the first and second orifices 84, 86.

In certain examples, a filter such as a filter screen 98 can be mounted to the valve body 50 (see Figure 3). In one example, the filter screen 98 can be crimped on the valve body 50 and can circumferential ly surround the valve body 50. The filter screen 98 can function to filter hydraulic fluid before the hydraulic fluid reaches the actuator 22. In other examples, the filter screen 98 can be disposed within the valve body 50 (see Figure 3B). For example, the filter screen 98 can be disposed between an inner surface of the valve body 50 and outer peripheries of the valve members 66, 68.

Sealing also can be provided between the valve body 50 and the manifold 26. For example, O-ring seals 100 surrounding the valve axis 54 can provide radial seals (e.g., seals that are compressed radially relative to the axis 54)

circumferentially between the exterior of the valve body 50 and the manifold 26 (see Figure 3). The O-ring seals 100 can be axially spaced apart from one another along a length of the valve body 50. In certain examples, the first and second orifices 84, 86 as well as the filter screen 98 can be positioned axially between the O-ring seals 100. In certain examples, an O-ring seal 102 also can be provided on the plug 90 to provide circumferential and radial sealing between the plug 90 and the manifold 26.

In one example, an orifice 104 can be defined by the second valve member 68. The orifice 104 can extend through the piston head 76 between the first and second interior regions 56a, 56b of the valve body 50. The purpose of the orifice 104 is to allow a small amount of flow to move from through the piston head 76 from the first interior region 56a to the second interior region 56b when the second valve member 68 is moved from the closed position to the open position. This prevents the second valve member 68 from being hydraulically locked in the event the first orifice 84 is effectively plugged.

It will be appreciated that material selection can be used for the various components of the valve assembly 36 to provide for enhanced sealing. For example, referring to Figures 3 and 3A, the valve body 50 and thus the first and second valve seats 58, 60 can be made of a polymeric material, while the first and second valve members 66, 68 as well as the plug 90 can be made of a metal material. In one example, the metal material is a non-magnetic material, such as stainless steel (e.g., 440C stainless steel). In one example, the polymeric material of the valve body 50 can include a plastic material. It will be appreciated that the plastic material can be a fiber reinforced plastic material. In one example, the fiber reinforced plastic material is reinforced by carbon fibers. In one example, the polymeric material includes

PolyEtherEtherKetone (PEEK). In one preferred example, the material includes PEEK reinforced with 20%-40% carbon fiber, or preferably about 30% carbon fiber.

Figures 4 and 4 A show an alternative valve device 124 having a valve manifold 126 defining a pump port 128, a tank port 132, and a hydraulic actuator port 134. The valve device 124 includes a valve assembly 136 having a valve body 150 that is integrally formed with a plug portion 190, which is threaded into a port 192 of the manifold 126. The valve assembly 136 includes first and second valve members 166, 168 that operate similar to the first and second valve members 66, 68. The first and second valve members 166, 168 are both poppet members, preferably constructed of a polymeric material of the type previously described. The second valve member 168 can include an elongate stem 172 having a protective metal cap 193 for preventing wear corresponding to contact with a metal mechanical actuation device, such as the mechanical actuator 42.

The valve body 150 can include a main body 150a and an end piece 150b. The end piece 150b can be pressed into the end of the main body 150a and secured by a press-fit connection or other type of coupling (e.g., threaded, bonded, welded, etc.). The main body 150a and the end piece 150b can be constructed of a metal material, such as stainless steel. The end piece 150b can be compressed against a corresponding angled surface 155 of the manifold when plug portion 190 of the main body 150a is threaded into the port 192. In this way, sealing can be provided (e.g., sealing compressed in an axial direction) between the manifold 126 and the end of the valve body 150.

Figure 5 shows a further valve device 224 in accordance with the principles of the present disclosure. The valve device 224 includes a valve manifold 226 defining a pump port 228, a tank port 232, and a hydraulic actuator port 234. A valve assembly 236 controls flow between the pump port 228 and the hydraulic actuator port 234, and between the hydraulic actuator port 234 and the tank port 232. The valve assembly 236 functions in a manner similar to those previously described. However, valve assembly 236 has been modified to include only one orifice 284 that provides fluid communication between an interior of a valve body 250 of the valve assembly 236 and the hydraulic actuator port 234. Thus, the single orifice 284 accommodates both flow from the valve assembly 236 to the hydraulic actuator port 234, and flow from the hydraulic actuator port 234 to the valve assembly 236. Additionally, the valve assembly 236 includes a first valve member 266 and a second valve member 268. In certain examples, the first valve member 266 is in the form of a ball and the second valve member 268 in the form of a poppet. In the example shown, the poppet 268 has an end portion 269 that fits inside a spring 278 used to bias the first and second valve members 266, 268 to closed positions relative to their respective valve seats 258, 260. In certain examples, the second valve member 268 does not divide the interior of the valve body 250 into sections. Rather, the single orifice 284 defined by the valve body 250 is located between the first and second valve members 266, 268.

Figure 6 is still another valve device 324 in accordance with the principles of the present disclosure. Valve device 324 has the same basic design as the valve device 224, except that the first and second valve members 366, 368 of the valve assembly 336 are depicted as both being spherical balls instead of the spherical ball 266 and poppet 268 of the valve assembly 236.

In certain examples, an extension/retraction position of the actuator 22 can be controlled by controlling the size of the fluid flow gap (i.e., the cross-sectional area of the flow passage between the valve member and the valve body) between the valve members 66, 166, 266, 68, 168, 268 and the valve body 50, 150, 250. In certain examples, an extension/retraction speed of the actuator 22 can be controlled by controlling the size of the fluid flow gap between the valve members 66, 166, 266, 68, 168, 268 and the valve body 50, 150, 250. The positions of the valve members can be controlled by a solenoid or other means. The valve members can include valve spools or other type of members suitable for use in proportional flow control valves.

In one example, the flow rate and thus the speed of the actuator 22 can be proportional to the size of the flow gap. For example, a smaller fluid flow gap between the first valve member 66, 166, 266 and the valve opening 62, 162, 262 may result in a slower extension of the actuator 22 compared to a larger fluid flow gap. A smaller fluid flow gap between the second valve member 68, 168, 268 and the valve opening 64, 164, 264 may result in a slower retraction of the actuator 22 compared to a larger fluid flow gap. Accordingly, the speed of retraction of the actuator 22 may be controlled by the mechanical actuator 42. The mechanical actuator 22 also can be used to close the fluid flow gap upon the actuator 22 reaching a desired retraction position.

In certain examples, the first valve member 66, 166, 266 and/or the valve body 50, 150, 250 can be modified to precisely control the size of the fluid flow gap between the first valve member 66, 166, 266 and the valve opening 62, 162,

262. Accordingly, the speed and extension distance of the actuator 22 can be precisely controlled using the modified first valve member 66, 166, 266 and/or the modified valve body 50, 150, 250.

In certain examples, the valve device 24, 124, 224, 324 includes valve members 66, 166, 266, 68, 168, 268 that can be controlled sufficient to enable an operator to select a fluid flow gap between the valve member and the respective valve opening. In some such examples, a single opening can be utilized in place of the orifices 43, 84, 86, 184, 186. The single opening can be larger than the orifice 43. In an example, the single opening would be sufficiently large to not meaningfully restrict the fluid passing from the interior of the valve body 50, 150, 250 to the actuator 22. Rather, restriction/management of the fluid would be controlled by the fluid gap size. In other examples, the proportional flow devices can be used in combination with an orifice (e.g., orifice 43) or orifices (e.g., 84, 86, 184, 186) defined by the valve body.

Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and spirit of this disclosure, and it should be understood that the scope of this disclosure is not to be unduly limited to the illustrated examples set forth herein.