Press-fit check valve for a hydraulic clamp reservoir with metered return flow

Abstract

Check valve (40, 70, 80, 90, 120, 140) for pressing into a check valve counterbore (32) of a hydraulic clamping body (28, 30), wherein the check valve (40, 70, 80, 90, 120, 140) comprises: a support (44, 126, 146) comprising an open support end, a closed support end opposite the open support end, a cylindrical side wall extending between the open support end and the closed support end, wherein the support side wall has a support flange (48, 124, 144) at the open support end and at least one support opening extending through the cylindrical side wall; a seat (46, 72, 82, 92, 150) comprising a cup-shaped seat wall with a radially symmetrical profile tapering from a first open end to a second open end and having a shoulder (47) between the first open end and the second open end, wherein the shoulder (47) is in contact with the mounting flange (48, 124, 144), wherein a seat opening extends through the seat (46, 72, 82, 92, 150) and forms a cavity between the mounting (44, 126, 146) and the seat (46, 72, 82, 92, 150), and wherein the first open end of the seat is pressable into the cylindrical wall of the check valve counterbore (32), wherein the seat (46, 72, 82, 92, 150) further comprises a plurality of The first open end comprises webs (51, 52, 53, 54) which are separated by web openings (50, 128, 148); a ball (12) which is received in the cavity, wherein the second open end of the seat (46, 72, 82, 92, 150) can be sealed by the ball (12); a spring (14) which is received in the cavity and has a first end which is in contact with the holder (44, 126, 146) and a second end which is in contact with the ball (12) in order to bias the check valve (40, 70, 80, 90, 120, 140) to a closed position in which the ball (12) sits in the second open end to seal the seat opening; and wherein the mounting flange (48, 124, 144) has at least one return slot (56, 122, 142) which allows hydraulic fluid to flow back past the mounting flange (48, 124, 144), and wherein the return slot (56, 122, 142) and the web openings (50, 128, 148) provide a return path from a piston counterbore (34) in the hydraulic clamping body (28, 30) to a pressurized hydraulic fluid reservoir.

Description

BACKGROUND OF THE INVENTION AREA OF THE INVENTION

[0001] The invention relates to the field of valves. In particular, the invention relates to a check valve for a hydraulic clamp. DESCRIPTION OF THE STATE OF THE ART

[0002] A chain tensioner is used to control the chain and absorb slack as it moves around a series of sprockets. Chain slack varies as the engine temperature rises and as the chain wears. As a chain wears, it stretches, and its slack increases. This increased slack can cause noise, slippage, or the chain skipping teeth on the sprocket. If this increasing chain slack is not addressed in an engine with a chain-driven camshaft, the engine can be damaged because the camshaft timing will be misaligned by an angle due to the slippage or skipping of teeth.

[0003] A hydraulic chain tensioner uses hydraulic fluid to maintain tension in the chain and typically includes at least one check valve. Oil must flow through the check valve and into a high-pressure chamber of the tensioner as the piston extends to accommodate chain slack. If the check valve's flow restriction becomes too large, the piston will not have enough oil volume to maintain its extended length. As the chain begins to push the piston back into the tensioner, the oil attempts to flow back out of the check valve. At this point, the check valve ball must move to seal the oil passage. If the response time is too slow, it takes too long to build up the necessary pressure to support the piston, and chain control becomes problematic. These two functions of the check valve affect the performance of a hydraulic chain tensioner.

[0004] In hydraulic tensioners, a slide-in check valve assembly is typically used within the high-pressure chamber. These assemblies incorporate a plastic component that allows a metered return of hydraulic fluid to the reservoir. The check valve assembly is adapted to the plastic component to form a seal with the tensioner body or a vent when a metered return of the hydraulic fluid is required. If the pressure of the hydraulic fluid in the piston bore becomes greater than the pressure of the hydraulic fluid in the reservoir due to the pressure from the tensioned chain, a return path allows a portion of the hydraulic fluid to flow back into the piston bore to retract the piston and relieve some of the pressure in the piston bore. A check valve for a vehicle brake control device is known from JP 2006-322521A.DE 10 2005 048 412 A1 and US 2010 / 0 087 285 A1 disclose known check valves for chain tensioners. SUMMARY OF THE INVENTION

[0005] The object of the present invention is to provide a simplified check valve for a hydraulic clamping device that enables improved control of the hydraulic fluid flow through the check valve. This object is achieved by the features of claims 1 and 4.

[0006] A press-fit check valve for a hydraulic clamp comprises a holder, a seat, a ball, and a spring. The check valve seat is pressed against the wall of the check valve counterbore of the hydraulic clamp body. In some embodiments, the seat is cup-shaped to provide a predetermined degree of press-fit retention force for the pressed-in check valve. The seat comprises a plurality of webs separated by web openings. A return path past the pressed-in check valve is provided by a combination of the web openings and at least one return slot through a flange of the holder. In some embodiments, a lip at the outer end of the check valve counterbore prevents the seat from slipping out of the counterbore.

[0007] In a first embodiment, a check valve for press-fitting into a counterbore of a hydraulic clamping body comprises a holder, a seat, a ball, and a spring. The holder comprises an open holder end, a closed holder end opposite the open holder end, a cylindrical side wall extending between the open holder end and the closed holder end, and at least one holder opening extending through the cylindrical side wall. The holder side wall includes a holder flange at the open holder end. The seat comprises a cup-shaped seat wall with a radially symmetrical profile that tapers from a first open end to a second open end and has a shoulder between the first and second open ends. The shoulder is in contact with the holder flange.A seat opening extends through the seat, and a cavity is formed between the holder and the seat. The first open end of the seat can be pressed into a cylindrical wall of the check valve counterbore. The ball is received in the cavity. The second open end of the seat can be sealed by the ball. The spring is received in the cavity and has a first end that contacts the holder and a second end that contacts the ball, in order to pre-tension the check valve to a closed position in which the ball seals the seat opening.

[0008] In other embodiments, a hydraulic clamp comprises a hydraulic clamp body with a check valve counterbore and the check valve pressed into the check valve counterbore according to the first embodiment.

[0009] In another embodiment, a hydraulic clamp comprises a hydraulic clamp body with a counterbore for a check valve and a check valve pressed into the counterbore. The check valve comprises a holder comprising an open holder end, a closed holder end opposite the open holder end, a cylindrical side wall extending between the open holder end and the closed holder end, and at least one holder opening extending through the cylindrical side wall. The holder side wall includes a holder flange at the open holder end.The check valve also includes a seat with a first open end, a second open end opposite the first open end, a shoulder between the first and second open ends that contacts the mounting flange to form a cavity between the mounting and the seat, and a seat opening extending through the seat. The check valve also includes a ball that is received in the cavity and sits in the second open end of the seat. The check valve also includes a spring that is received in the cavity and has a first end that contacts the mounting and a second end that contacts the ball to bias the check valve to a closed position in which the ball sits in the second open end to seal the seat opening. The seat includes a plurality of webs at the first open end that are separated by web openings.The webs are pressed into a cylindrical wall of the check valve counterbore. The mounting flange has an upper surface that contacts a rear surface of the check valve counterbore, and a lower surface opposite the upper surface that contacts the shoulder of the seat. The mounting flange has at least one return slot that allows hydraulic fluid to flow back around the mounting flange. The return slot and the web openings provide a return path from a piston counterbore in the hydraulic clamping body to a pressurized hydraulic fluid reservoir. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a perspective cross-sectional view of a ball check valve for informational purposes. Fig. Figure 2 shows a perspective cross-sectional view of the check valve for informational purposes. Fig. 1, which is pressed into a hydraulic clamping body. Fig. Figure 3 shows, for informational purposes, an enlarged view of the check valve area of ​​the hydraulic clamping assembly. Fig. 2. Fig. Figure 4 shows a perspective cross-sectional view of a check valve with a cup-shaped seat with ribs pressed into a hydraulic clamping body, in an embodiment of the present invention. Fig. Figure 5 shows an enlarged perspective cross-sectional view of the check valve area of ​​the hydraulic clamping assembly of Fig. 4. Fig. Figure 6 shows an enlarged cross-sectional view of the check valve area of ​​the hydraulic clamping assembly of Fig. 4, where a return path is shown. Fig. Figure 7 shows an enlarged cross-sectional view of the check valve area of ​​a hydraulic clamping arrangement without return for informational purposes. Fig. Figure 8 shows a perspective cross-sectional view of a check valve with a cup-shaped seat pressed into a hydraulic clamping body in an embodiment of the present invention. Fig. Figure 9 shows a perspective cross-sectional view of a check valve with a cup-shaped seat pressed into a hydraulic clamping body, in a further embodiment of the present invention. Fig. Figure 10 shows a perspective cross-sectional view of a check valve with a cup-shaped seat pressed into a hydraulic clamping body, in yet another embodiment of the present invention. Fig. 11 shows a comparison to Fig. 5 Rotated perspective cross-sectional view of the check valve and hydraulic clamping body of Fig. 5. Fig. Figure 12 shows the same perspective cross-sectional view as in Fig. 11 and represents the check valve of Fig. 5 into the hydraulic clamping body of Fig. 2 pressed in. Fig. Figure 13 shows a top view of the check valve of Fig. 4 with the return holes in the mounting flange. Fig. Figure 14 shows a top view of the check valve for informational purposes. Fig. 7 without return holes in the mounting flange. Fig. Figure 15 shows a perspective view of a check valve with straight flow slots for the return flow in an embodiment of the present invention. Fig. Figure 16 shows a perspective view of a check valve with coiled flow slots for the return flow in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] A check valve assembly is pressed into a counterbore located in the hydraulic fluid reservoir of a hydraulic clamp. Incorrect pressing can cause the check valve to move within the counterbore and result in inadequate control of the hydraulic fluid flow through the check valve. As is typical for press-fit components, tight tolerances of the mating parts are required to maintain the press fit during operation. In some embodiments, the pressed-in check valve incorporates one or more features that reduce the tolerance requirements and the cost of manufacturing the pressed-in check valve and clamp body, as well as the assembly of the hydraulic clamp.In some embodiments, the check valve seat is fitted with a bracket of the hydraulic tensioner to accommodate components of the check valve, including, but not limited to, a ball or disc and a spring.

[0011] In some embodiments, the valve seat comprises a cup-shaped profile. "Cup-shaped" here can be understood as any radially symmetrical profile that tapers from a first open end to a second open end and may include straight or curved sections to form the shape of the walls of a cup. The cup-shaped profile preferably includes a shoulder that, in the assembled check valve, is in contact with the bottom surface of the mounting flange.

[0012] In such embodiments, the valve seat wall preferably has a substantially uniform thickness from the first open end to the second open end and is preferably formed from a single piece of sheet metal. In some embodiments, the valve includes a set of at least two ribs to improve retention and to provide a return path for hydraulic fluid, which is typically oil, into the hydraulic fluid reservoir. In some embodiments, the shell structure includes two ribs. In some embodiments, the shell structure includes four ribs. In still other embodiments, the shell structure includes six or more ribs.

[0013] In some embodiments, the webs are separated by arc-shaped openings with a concave shape. In some embodiments, the webs are rounded webs, with the rounded openings separating the webs.

[0014] Methods for forming the shell structure of the seat may include, but are not limited to, stamping and deep-drawing processes. The seat is preferably made of steel. In a stamping process, a flat sheet of metal is placed in a stamping press, and a tool and the die surface press the metal into the desired shape. In a deep-drawing process, a flat piece of sheet metal is drawn radially into a die by the mechanical action of a punch.

[0015] The shell is preferably shaped to provide a predetermined degree of press-fit retention force for the pressed-in check valve. Adjusting the length and angle of the section of the seat in contact with the countersunk bore (i.e., in embodiments with ribs, the ribs), the contact surface, and the surface treatment of the bore surface determine the degree of press-fit retention force. Increasing the contact angle from zero is expected to increase the interference force and retention; however, if the angle becomes too large, material failure or yielding may occur beyond a certain point. Increasing the length is expected to increase the contact area and thus the retention. It is also expected that increased surface roughness will increase the friction between the press-fit surfaces and improve retention.In some embodiments, the machining tolerances for the countersink can be increased to reduce unit costs.

[0016] The check valve arrangement preferably eliminates at least one conventional component, a plastic seal, which reduces the complexity of the assembly process.

[0017] Additional retention methods can be used in conjunction with the press fit. A check valve counterbore with a slight undercut can be used to create a lip that can snap into the counterbore and prevent slippage. The material can be die-forged after the valve is inserted to reduce the diameter of the counterbore, thus preventing axial movement of the parts. In alternative embodiments, die-forging the seat to increase its outside diameter may be possible if done carefully to prevent cracking or other damage to the check valve. Die forging is a forging process in which the dimensions, usually the diameter, of an object are changed using dies or dies into which the object is pressed.The seat can be laser-welded into the bore using typical weld adhesion, either to create a raised ring of material formed by laser heat penetration and acting as a material stop, or to improve the hold by roughening the surface.

[0018] By eliminating the plastic component typically used to form a seal or vent with the clamping body, a metered return flow is preferably achieved by incorporating a single opening of one or more specified sizes directly into the mounting flange. These openings can be formed as part of the stamping or deep-drawing process with secondary machining, while smaller diameters can also be created using a water jet or laser. Openings in the seat shell between the webs provide a return path past the seat and into the hydraulic fluid reservoir.

[0019] Forming, machining, or laser cutting can be used to create a flow path or helical path on the mounting flange or on the mating component, which in this case is the hydraulic clamping body. The mounting is preferably made of steel. The mounting wall preferably has a substantially uniform thickness from the flange at one end to the closed top at the other end and is preferably made from a single piece of sheet metal. The mounting preferably comprises the mounting flange at the open end of the mounting, a cylindrical side wall extending from the mounting flange with at least one opening in the side wall, and a closed end opposite the open end of the mounting.

[0020] With reference to Fig. Figure 1 comprises the ball check valve 10, a ball 12, a spring 14, a seat 16, and a retainer 18. The ball 12 and the spring 14 are held between the seat 16 and the retainer 18. The seat 16 includes a seat opening 20, against which the ball 12 is biased by the spring 14 to keep the check valve 10 open. Fig. The check valve 10 is pre-tensioned to the closed position shown in Figure 1. Pressurized fluid flows into the check valve 10 through the seat opening 20, pushing the ball 12 away from the seat 16 against the pre-tension of the spring 14, thus moving the check valve 10 into an open position. The holder 18 includes at least one holder opening 22 for the flow of pressurized fluid from the check valve 10 when the check valve 10 is in an open position.

[0021] In Fig. 2-3 The check valve 10 was pressed into the check valve counterbore 32 of the hydraulic clamping body 28 of a hydraulic clamp. The piston counterbore 34 for the hydraulic piston (not shown), a connecting bore 35, which provides a flow path between the piston counterbore 34 and the check valve 10, and a mounting bore 36 are in Fig. 2 also shown. The check valve counterbore 32 is preferably cylindrical, and the seat 16 is machined to tight tolerances to ensure that the check valve 10 is retained in the check valve counterbore 32.

[0022] Fig. Figures 4-5 show an exemplary check valve 40 according to the present invention, comprising a cup-shaped seat 46 pressed into the check valve counterbore 32 of a hydraulic clamping body 30. The check valve counterbore 32 includes a lip 38 to assist in retaining the check valve 40. The check valve 40 also includes a ball 12, a spring 14, and a retainer 44. The web openings 50 of the seat 46, which define the edges of the webs 52, 54, are located in the Fig. 5 and Fig. 6 easier to recognize. Two of the four bridges, 52 and 54, are in the Fig. The cross-sectional view shown in Figure 5 is visible. How best to view it in Fig. As shown in Figure 6, the seat 46 includes a shoulder 47 which is in contact with the bottom surface of the mounting flange 44 in the built-in press-fit check valve 40.

[0023] The web openings 50, in combination with the flow passages 56 in the flange 48 of the bracket 44, provide a return path 60 from the piston sink bore 34 to the hydraulic fluid reservoir (not shown), as indicated by the dashed line in Fig. Figure 6 shows that the return path 60 provides a metered return of hydraulic fluid from the piston counterbore 34 to the hydraulic fluid reservoir when the check valve 40 is in a closed position. Changing the size, position, shape, and number of the flow passages 56 and web openings 50 alters the metered return, thus enabling a desired adjustment of the metered return for a check valve of a hydraulic clamp for a given application.

[0024] In some situations, it is desirable to have no return flow from the high-pressure chamber to the hydraulic fluid reservoir. In the Fig. In the non-inventive embodiment shown in Figure 7, the mounting flange 19 of the press-fit check valve 65 has no flow passages and forms a seal with the rear wall of the check valve counterbore 32 to prevent backflow past the mounting flange 19 of the bracket 18 of the check valve 65. The seat 46 comprises a shoulder 47 that is in contact with the bottom surface of the mounting flange 19 in the installed press-fit check valve 65. Although the check valve counterbore 32 in Fig. 6 has a lip 38 and the check valve counterbore 32 in Fig. 7 has no lip, a lip 38 may be present or absent regardless of whether the return flow through the check valve is allowed or not.

[0025] The shape of the shell preferably provides the insertion holding force for the press-fit check valve. Any one of a series of different shell construction profiles can be used in accordance with the present invention, depending on the desired insertion holding force. Fig. 8 The lower section of the profile of the seat 72 of the press-fit check valve 70 is at a slight angle (essentially parallel) with respect to the wall that defines the check valve counterbore 32. In Fig. 9 The lower section of the profile of the seat 82 of the press-fit check valve 80 is at a large angle with respect to the wall that defines the check valve counterbore 32. In Fig. 10 The lower section of the profile of the seat 92 of the press-fit check valve 90 is at a medium angle with respect to the wall that defines the check valve counterbore 32. Although the seats 72, 82, 92 in Fig. 8, Fig. 9 and Fig. Although the clamping bodies 30 are shown without webs and web openings, webs and web openings with the profiles shown can be used in accordance with the spirit of the present invention. Fig. 8, Fig. 9 and Fig. As shown in Figure 10 with lips 38, the illustrated check valves 70, 80, 90 can alternatively be pressed into the check valve counterbore 32 of a hydraulic clamping body 28 without a lip.

[0026] In some embodiments, a snap-in undercut feature can be used, as described above, to provide retention in the countersunk bore. The retention by the lip 38 of the clamping body 30 is at an angle of Fig. 11 more clearly visible, which essentially involves an angular rotation in relation to the view of Fig. Figure 5 represents. In some such embodiments, the seat 46 of the press-fit check valve 40 is angled to have an outer diameter at the base that is larger than the inner diameter of the lip 38 and is preferably formed by an undercut of the check valve counterbore 32. The webs 52, 54 may deform slightly inwards during press-fitting to allow the seat 46 to slide completely past the lip 38, but to snap back after passing the lip 38 to hold the check valve 40 in the counterbore 32.

[0027] In other embodiments, the hold in the countersunk bore is provided without a snap-in undercut feature, as in Fig. Figure 12 shows that in such embodiments, the webs 52, 54 of the seat 46 of the press-fit check valve 40 are pressed against the inner wall of the check valve counterbore 32 of the hydraulic clamping body 28. In such embodiments, the webs 52, 54, which press against the inner wall of the counterbore 32, alone ensure retention in the counterbore. In some embodiments, the pressing in is carried out using conventional press-fit methods.

[0028] In Fig. Figure 13 shows a top view of the check valve 40 of the hydraulic clamping device. Fig. 4. The flow passages 56 through the flange 48 of the bracket 44, which allow for metered return flow, are shown. All four web openings 50 and all four webs 51, 52, 53, 54 of the seat 46, as well as all four flow passages 56 in the bracket 44, are visible. Although the flow passages 56 are shown aligned with the web openings 50 here, the flow passages 56 can be offset from the web openings 50 by rotating the orientation of the seat 46 relative to the bracket 44 to increase the path length of the return flow.

[0029] Fig. Figure 14 shows a top view of the check valve 65 of the hydraulic clamping device. Fig. 7, to better show the flange 19 of the bracket 18, which prevents backflow. All four web openings 50 and all four webs 51, 52, 53, 54 of the seat 46, as well as all four flow passages 56 in the bracket 44, are visible.

[0030] Alternative metered return paths in the mounting flange can be used to allow return from the top of the flange 124, 144 to the outer edge of the flange 124, 144 instead of return from the top to the bottom through the flange 48. Fig. Flow slots 122 extend radially outward as grooves in the top surface of the flange 124 of the bracket 126 of the check valve 120. Since the upper surface of the flange 124 is pressed against the clamping body, the inner section of the flow slot 122 is accessible to the hydraulic fluid from the piston counterbore 34, and the outer section of the flow slot 122 is accessible to the fluid reservoir via the check valve counterbore 32 and the web openings 128. The return flow of hydraulic fluid must pass through the flow slots 122 to bypass the flange 124. The number, size, and shape of the flow slots 122 can be selected to provide a specific metering of the return flow. Although the flow slots 122 are shown here as being completely enclosed by the web openings 128 of the seat 130 in Fig. As 15 are shown offset to maximize the length of the return path, any degree of dislocation or no dislocation at all can be used in accordance with the spirit of the present invention.

[0031] Finally, it shows Fig. 16 a more convoluted metered return path in the flange 144 of the bracket 146 of the check valve 140. A flow slot 142 extends circumferentially as a groove in the top surface of the flange 144 for approximately three-quarters of its circumference, with the ends of the groove extending radially to the outer edge of the flange 144. Since the upper surface of the flange 144 is pressed against the clamping body, the return flow of hydraulic fluid must pass through the flow slot 142 to bypass the flange 144. In some embodiments, one or more sections of the circumferential portion of the flow slot 142 are completely concealed by the clamping body in the assembled hydraulic clamp. In other embodiments, the circumferential portion is partially concealed by the clamping body in the assembled hydraulic clamp.The number, size, and shape of the flow slots 142 can be selected to provide a predetermined dosage of the return flow. The ends of the flow slot 142 are shown here aligned with the web openings 148 of the seat 150. Fig. Although a single flow slot 142 is shown here extending circumferentially over three-quarters of the circumference, with the ends extending radially to the outer edge of the flange 144, any circumferential length of the groove and any number of flow slots can be used in accordance with the present invention.

[0032] Although some figures show a seat with ribs and rib openings at the outer end of the seat, and some other figures do not show a seat with ribs and rib openings at the outer end of the seat, the seats of each of the press-fit check valves shown and described can be designed with or without ribs and rib openings in accordance with the spirit of the present invention; however, if a return flow is desired, a seat should preferably have at least two rib openings.

[0033] Although the profile defining the edge between the webs and the web openings is generally depicted in the figures as a curved, arcuate or rounded shape, if desired, any shape that provides retention in the check valve counterbore and provides a flow path to enable metered return flow may be used in accordance with the spirit of the present invention.

[0034] Although some figures show a clamping body with a lip at the outer end of the check valve counterbore, and some other figures show a clamping body without a lip, in the spirit of the present invention any of the press-fit check valves shown or described can be pressed into a clamping body with a lip at the outer end of the check valve counterbore or into a clamping body without a lip.

Claims

[1] Check valve (40, 70, 80, 90, 120, 140) for pressing into a check valve counterbore (32) of a hydraulic clamping body (28, 30), wherein the check valve (40, 70, 80, 90, 120, 140) comprises: a support (44, 126, 146) comprising an open support end, a closed support end opposite the open support end, a cylindrical side wall extending between the open support end and the closed support end, wherein the support side wall has a support flange (48, 124, 144) at the open support end and at least one support opening extending through the cylindrical side wall; a seat (46, 72, 82, 92, 150) comprising a cup-shaped seat wall with a radially symmetrical profile tapering from a first open end to a second open end and having a shoulder (47) between the first open end and the second open end, wherein the shoulder (47) is in contact with the mounting flange (48, 124, 144), wherein a seat opening extends through the seat (46, 72, 82, 92, 150) and forms a cavity between the mounting (44, 126, 146) and the seat (46, 72, 82, 92, 150), and wherein the first open end of the seat is pressable into the cylindrical wall of the check valve counterbore (32), wherein the seat (46, 72, 82, 92, 150) further comprises a plurality of The first open end comprises webs (51, 52, 53, 54) which are separated by web openings (50, 128, 148); a ball (12) which is received in the cavity, wherein the second open end of the seat (46, 72, 82, 92, 150) can be sealed by the ball (12); a spring (14) which is received in the cavity and has a first end which is in contact with the holder (44, 126, 146) and a second end which is in contact with the ball (12) in order to bias the check valve (40, 70, 80, 90, 120, 140) to a closed position in which the ball (12) sits in the second open end to seal the seat opening; and wherein the mounting flange (48, 124, 144) has at least one return slot (56, 122, 142) which allows hydraulic fluid to flow back past the mounting flange (48, 124, 144), and wherein the return slot (56, 122, 142) and the web openings (50, 128, 148) provide a return path from a piston counterbore (34) in the hydraulic clamping body (28, 30) to a pressurized hydraulic fluid reservoir. [2] Check valve (40, 70, 80, 90) according to claim 1, wherein the at least one return slot (56) is at least one flow passage through the mounting flange (48) from an upper surface of the mounting flange (48) to a lower surface of the mounting flange (48). [3] Check valve (120, 140) according to claim 1, wherein the at least one return slot (122, 142) is at least one groove in an upper surface of the mounting flange (124, 144) extending to an outer edge of the mounting flange (124, 144). [4] Hydraulic clamps, comprising: a hydraulic clamping body (28, 30) with a counterbore check valve (32); and a check valve (40, 70, 80, 90, 120, 140) which is pressed into the check valve counterbore (32, 34), wherein the check valve (40, 70, 80, 90, 120, 140) comprises: a support (44, 126, 146) comprising an open support end, a closed support end opposite the open support end, a cylindrical side wall extending between the open support end and the closed support end, wherein the support side wall has a support flange (48, 124, 144) at the open support end and at least one support opening extending through the cylindrical side wall; a seat (46, 72, 82, 92, 150) with a first open end, a second open end opposite the first open end, a shoulder (47) between the first open end and the second open end, which is in contact with the mounting flange (48, 124, 144) to form a cavity between the mounting (44, 126, 146) and the seat (46, 72, 82, 92, 150), a seat opening extending through the seat (46, 72, 82, 92, 150), and a plurality of webs (51, 52, 53, 54) at the first open end, which are separated by web openings (50, 128, 148), wherein the webs (51, 52, 53, 54) are incorporated into a cylindrical wall of the are pressed into the check valve counterbore (32); a ball (12) which is received in the cavity and sits in the second open end of the seat (46, 72, 82, 92, 150); and a spring (14) which is received in the cavity and has a first end which is in contact with the holder (44, 126, 146) and a second end which is in contact with the ball (12) to bias the check valve (40, 70, 80, 90, 120, 140) to a closed position in which the ball (12) sits in the second open end to seal the seat opening; wherein the mounting flange (48, 124, 144) has an upper surface that is in contact with a rear surface of the check valve counterbore (32), and a lower surface opposite the upper surface that is in contact with the shoulder (47) of the seat (46, 72, 82, 92, 150), wherein the mounting flange (48, 124, 144) has at least one return slot (56, 122, 142) that allows hydraulic fluid to flow back past the mounting flange (48, 124, 144), and wherein the return slot (56, 122, 142) and the web openings (50, 128, 148) provide a return path from a piston counterbore (34) in the hydraulic clamping body (28, 30) to a Provide a pressurized hydraulic fluid reservoir. [5] Hydraulic clamp according to claim 4, wherein the at least one return slot (56) is at least one flow passage through the mounting flange (48) from an upper surface of the mounting flange (48) to a lower surface of the mounting flange (48). [6] Hydraulic clamp according to claim 4, wherein the at least one return slot (122, 142) is at least one groove in an upper surface of the mounting flange (124, 144) extending to an outer edge of the mounting flange (124, 144). [7] Hydraulic clamp according to claim 4, wherein the hydraulic clamp body (28, 30) comprises a lip (38) at an outer end of the check valve counterbore (32, 34), and the lip (38) prevents the first open end of the seat (46, 72, 82, 92, 150) from slipping out of the check valve counterbore (32). [8] Hydraulic clamp according to claim 4, wherein the seat (46, 72, 82, 92, 150) is shell-shaped and has a seat wall with a radially symmetrical profile that tapers from the first open end to the second open end.

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