MXPA96000188A - Brake actuator operated by fluid with valve retenc - Google Patents

Abstract

The present invention relates to a brake actuator for a vehicle, comprising: a housing with an actuator stem opening in one end portion and a ventilation opening in another end portion, the vent opening defined by an edge of accommodation, the housing having an inner surface and an outer surface, a movable member disposed within the housing, the movable member dividing the interior of the housing in a first chamber including the end portion mentioned first and a second chamber including the other end portion movable reciprocally therein in response to the delivery and discharge of fluid under pressure to and from the second chamber, respectively, an actuator rod operatively connected to the movable and movable member const to operation of a brake, the actuator stem projecting to through the actuator stem opening in the end portion first mentioned, a spring disposed in the first chamber in a position for urging the movable member to a first position, where the second chamber is collapsed upon the occurrence of pressurized fluid discharge from the second chamber, a passage between the first and second chambers for passing fluid between the two, a valve in the passage between the first and second chambers to allow the flow of fluid from the second to the first chamber but prevent the flow of fluid from the first to the second chamber, and a check valve mounted in the vent opening in the other end position of the housing for venting fluid in the first chamber when pressurized fluid is supplied to the second chamber to move the movable member towards the other end of the housing to collapse the spring, the improvement comprising : the check valve having: a generally tubular elastomeric body having an opening extending therethrough with opposite ends s of entry and exit, the body also having an inner lip and an outer lip, each separated from the other and extending radially outward from the body to define a channel between them, and the channel being dimensioned to receive loosely the edge with the inner and outer lips resting against the first and second surfaces, respectively, when the body is received in the opening: a substantially rigid plate having at least one bore and mounted to the body closer to the inner lip and the inlet end and embracing the opening said plate having a diameter sized to stiffen a portion of the tubular body, and a one-way valve disposed near the outer lip and the outlet end of the body to allow fluid flow from the inlet end through the outlet end and inhibit fluid flow from the outlet end through the inlet end, so that when the check valve is mounted inside of the opening, the plate will prevent removal of the check valve through the opening from the first surface to the second surface

Description

BRAKE ACTUATOR OPERATED BY FLUID WITH RETENTION VALVE INVENTOR: STEVEN. STOJIC, a citizen of the United States, residing at 324 North 145th Avenue, Holland, Michigan 49424, United States.

APPLICANT: NAI ANCHORLOK, INC., A society of * United States, residing at 1950 Industrial Boulevard, Muskegon, Michigan 49443-0425, United States.

Background of the Invention Field of the Invention The invention relates to brake actuators ~ Jfc operated by fluid for vehicles, and more particularly to a fluid operated actuator with a check valve for regulating the flow of fluid between the fluid operated brake actuator and the atmosphere. STATE OF THE PRIOR ART An air brake system for a vehicle such as a truck, bus or the like typically includes a brake shoe and drum assembly driven by a set actuator operated by the selective application of a fluid such as compressed air. Conventional air brake actuators have a service brake actuator for operating the brakes under normal driving conditions by applying compressed air and a spring or emergency brake actuator which causes the brakes to be actuated when it has been released air pressure. The emergency brake actuator includes a high force compression spring that applies the brake when air is released. This actuator is often called the spring brake. Typically, the spring brake actuator ~ is arranged in tandem with the service brake actuator. The spring brake actuator is typically divided into two chambers separated by a diaphragm and pressure plate, with the spring in one of the chambers acting between an end wall of the spring brake housing and the pressure plate. When total air pressure is applied to the opposite chamber, the air pressure acting against the diaphragm and the pressure plate compresses the spring. In many applications, a spring brake actuator rod is held in a retracted position by a relatively small return spring. In more recent applications, the spring brake actuator rod is integral with the pressure plate and is held in a retracted position by the air pressure. In both designs, the brake actuator piston rod Spring does not affect the normal operation of the brake. The service chamber is typically divided into two chambers by means of a diaphragm. Pressing the brake pedal during normal driving operation introduces compressed air into one of the chambers of the service brake actuator which, acting against the diaphragm, causes a service brake thrust rod to extend on the other side of the diaphragm and that the brakes are applied with an application force proportional to the air pressure in the service brake actuator. ^^ In the event of a loss of air pressure or an intentional escape of air from the spring brake actuator, the brake will be mechanically activated by the force of a large compression spring acting on the spring-loaded brake actuator stem. which, in turn, drives the service braking thrust rod to apply the brakes.Thus, the spring brake portion serves as both a parking brake and an emergency brake.In tandem actuator assemblies, the shank of ? spring brake thrust typically extends from a chamber in the spring brake portion, through an opening in a wall separating the spring brake actuator from the service brake actuator, and towards a chamber in the portion of service brake. Because at least one of the adjacent chambers is usually pressurized, an O-ring seal is provided in the opening around the Push rod. ^^ When air pressure is released from the spring brake actuator, the spring and the diaphragm extend significantly, expanding the volume of the spring brake actuator chamber containing the spring. As the volume of the spring brake actuator chamber increases, air must enter the expanded volume of the chamber to prevent sub-atmospheric pressure in the spring brake actuator chamber and thereby delay the application of the spring brake. ^. When the spring retracts, the volume of the spring chamber c contracts and air must be evacuated from the chamber. In many previous brake actuators, the spring chamber is simply open to the atmosphere through gates in the chamber housing. However, an open chamber allows garbage, salts, moisture and other undesirable materials to enter the spring chamber through the penstocks. With the advent of hollow actuator rods containing caging tools, the presence of foreign matter ? Within the actuator rod it has become a growing concern of brake designers. SUMMARY OF THE INVENTION The invention solves the problem of venting pressurized air from the spring chamber in a spring brake actuator to the atmosphere through the spring chamber housing while simultaneously preventing waste, salts, moisture and other undesirable materials enter the spring chamber by placing a check valve in an opening in the spring chamber to allow the flow of air only in the direction of the chamber of the spring-brake actuator to the atmosphere. According to a preferred embodiment of the invention, the check valve has a double redundant trap and prevents the entry of undesirable material into the brake. Also, the check valve is tamper resistant to prevent accidental removal of the check valve p ^ of the brake. The shape of the check valve is designed in Advantageous shape and the materials from which it is made are advantageously selected so as to retard the formation of ice and other similar materials on the external surface of the check valve, which formation could adversely affect the performance of the check valve. The design and material of the check valve also retards paint buildup in the check valve, which can be applied to the vehicle after the installation of the check valve. The invention relates to an improved brake actuator for a vehicle, comprising a housing with an actuator rod that opens into one end portion and a vent opening in the other end portion. A movable member is disposed within the housing and divides the interior of the housing into a first chamber that includes a end portion and a second chamber that includes the other end portion. The movable member moves reciprocally within the housing in response to the delivery and escape of pressurized fluid to and from the second chamber. An actuator rod is operatively connected to and movable with the movable member for operation of a brake actuator rod projecting through the actuator rod opening at the first mentioned end portion. A spring is disposed in the first chamber in a position to urge the movable member to a first position where the first chamber is expanded upon the occurrence of fluid leakage from the second chamber. A passage between the first and second chambers allows fluid to flow between the two chambers. A check valve is positioned in the passage between the first and second chambers to allow fluid to flow from the second to the first chamber, when pressurized fluid escapes from the second chamber. The check valve will close to prevent fluid flow when the second chamber is filled with fluid to * T pressure. The improvement in the brake actuator comprises a check valve mounted in the vent opening in the other end portion of the housing for venting fluid in the first chamber when pressurized fluid is supplied to the second chamber to move the movable member toward the chamber. another end of the housing to collapse the spring.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a fluid operated brake actuator having a check valve according to the invention; Figure 2 is an exploded view of the check valve shown in Figure 1; Figure 3 is an enlarged view of the check valve assembled in the closed position, as shown in Figure 1; _A Figure 4 is substantially identical to Figure 3, ^ except that the check valve is shown in the open position; and Figure 5 is an alternative embodiment of the check valve according to the invention. Detailed Description of the Drawings The invention relates to a fluid operated brake actuator with a check valve in a spring chamber. In one embodiment, the check valve is * a double redundant tamper resistant check valve. The check valve allows pressurized air to escape from the fluid operated brake while eliminating the flow of undesirable material such as garbage and water into the interior. Advantageously, the design and material of the check valve tend to inhibit the accumulation of a thin layer of ice and paint on the check valve.

In an advantageous use of the invention, the check valve is described in the context of a fluid operated brake actuator. However, the check valve can be used in many other different environments and is not limited to a fluid operated brake. It will be useful to first describe the fluid operated brake as it is the preferred environment for the check valve. Figure 1 illustrates a fluid operated brake actuator 10 having a general configuration well known in the art. The fluid operated brake actuator 10 comprises a service brake actuator 12 mounted in tandem in a spring brake actuator or emergency brake actuator 14. The fluid operated brake actuator 10 is of tandem construction; however, the invention can be used in any type of brake, including fluid operated spring-loaded brakes that are not in tandem in which the spring chamber is separated from the service chamber. A service brake thrust rod 16 extends from the service brake actuator 12 for reciprocating movement between a retracted position and an extended actuating position relative to the service brake actuator 12, and has an anvil 17 adapted for connect to a conventional brake shoe and drum assembly (not shown) in conventional manner. The reciprocating movement of the service brake push rod 16 provides means of activation to apply and release the brake alternately. The service brake actuator 12 has a housing defined by a cup-shaped service housing section 18 and a double cup-shaped adapter housing 20 joined by a clamp 22 to form a service brake chamber 23. The housing Adapter 20 is also sometimes known as a flange box. The service brake chamber 23 is divided into two sections by dividing means, such as a first elastomeric diaphragm 24 (also known as a service brake diaphragm) suspended within the service brake chamber 23.

The peripheral edge of the diaphragm 24 is secured in a fluid-proof housing between the cup-shaped service housing section 18 and the service side of the adapter housing 20 by the clamp 22. The first elastomer diaphragm 24 separates the service brake chamber 23 in two portions: a first serving chamber portion 26 and a second serving chamber portion * 28. The first serving chamber portion 26 communicates with a source of pressurized air (not shown) through an air service gate 42 in the adapter housing 20. The second serving chamber portion 28 is ventilated to the atmosphere through at least one opening 32 in the cup-shaped service housing section 18. In Figure 1, the first service chamber portion 26 is shown evacuated from so that the first elastomeric diaphragm 24 is forced against the adapter housing 20 due to the force of the compression spring 46 in the second service chamber portion 28. The service brake pushing rod 16 extends through a central opening 30 in the cup-shaped service housing section 18 and has a pressure plate 44 at its end inside the second service chamber portion 28. The pressure plate 44 bears against the first elastomeric diaphragm 24. A spring of compression 46 extends between the pressure plate 44 and the inner surface of the cup-shaped service housing section 18. A push rod guide 34 having an annular seat 40 is disposed within the central opening 30 to guide the reciprocal movement of the service brake thrust rod 16 within the central opening 30 and also for receiving the end of the compression spring 46 and retaining it in position around the central opening 30. The compression spring 46 urges the pressure plate 44 and the rod of service brake 16 to a fully retracted position, as depicted in Figure 1. To operate the service brake actuator 12, compressed air is introduced through an air service gate 42 towards the first service chamber portion 26 to create a force directed against the first elastomeric diaphragm 24 and pressure plate 44, enough to overcome the force of the compression spring 46, thereby extending the service brake pushing rod 16 to the driving position. The openings 32 allow rapid evacuation of air from the second service chamber section 23 when the service brake is actuated. Mounting brackets 47 are provided for mounting the fluid operated brake actuator 10 in a vehicle (not shown). The spring actuator or emergency brake actuator 14 has a housing defined by the spring side of the adapter housing 20 and a generally cylindrical spring head chamber 48, which is gripped to the spring side of the adapter housing 20. by a clamp 50 to form the spring brake chamber 51. The spring brake actuator is divided into two portions, preferably by dividing means such as a second elastomeric diaphragm 52, known as a spring brake diaphragm, which is suspended inside the spring brake chamber 51. The peripheral edge of the spring brake diaphragm 52 is secured in a ^ fluid-proof housing between the cylindrical head 48 and the spring side of the adapter housing 20 by the clamp 50. The second elastomeric diaphragm 52 divides the spring brake chamber 51 into two portions: a first spring brake chamber 62 and a second spring brake chamber 63. The second spring brake chamber 63 is filled with pressurized air supplied through a service gate of air 54 in the adapter housing 20 when the brake * emergency is in its normal released position, as shown in figure 1. The adapter housing 20 includes a dividing wall 35 which separates the attached service brake chamber 23 and the spring brake chamber 51. A brake actuator rod spring 56, aligned with the service brake pushing rod 16, has an end extending from the spring brake chamber 51 through a dividing wall opening 37 in the partition wall 35 for reciprocating movement through the dividing wall opening 37 between a retracted position and a driving position. One or more O-ring seals 36 are provided in the divider wall opening 37 through which reciprocates the spring brake actuator rod 56. A distal end 55 in the spring brake actuator 56 ends in a plate of reaction 66 in the first portion of service chamber 26, and which is received in an annular seat 67 when the brake actuator rod of - spring 56 is in the retracted position, as sketched in figure 1, a proximal, opposite end 57 of the actuator rod 56 extends through an opening 53 in the second elastomeric diaphragm 52 and terminates in a pressure plate 58 which it abuts on one end of a high force compression spring 60. The pressure plate 58 abuts one end of the compression spring 60.

A valve 86 extends through the plate * pressure and the elastomeric diaphragm for fluidly connecting the first and second spring brake chambers 62 and 63. When pressurized fluid is discharged from the second spring brake chamber, the valve 86 allows fluid flow from the second chamber of the second spring. spring brake 63 to the first spring brake chamber 62 to prevent a vacuum or low pressure area from developing in relation to the pressure in the second spring brake chamber 63, in the first brake chamber of w » 62 spring? The valve 86 has an outer tubular portion 88, which extends through the pressure plate 58 and the elastomeric diaphragm 52. A spring arm 89 is mounted on the lower end of the tubular portion 88. The spring arm closes the tubular portion 88 upon the addition of fluid under pressure to the lower spring chamber 63. When pressurized air is released from the lower spring chamber 63, the resilience Inherent # of the spring arm 89 removes the seal from the tubular portion 88 to fluidly connect the first spring brake chamber 62 and the second spring brake chamber 63. The valve 86 is further described in the United States patent application. United Series No. 08 / 213,441. The spring brake actuator rod 56 may be solid, but preferably it is a hollow tube or rod provided with a central bore 68 for accommodating a pin. brake release or caging tool 70. The central bore 68 of the spring brake actuator rod 56 receives the caging tool 70, which passes through aligned openings 69, 73 and 75 in the cylindrical head 48, the platen pressure 58 and the spring brake actuator rod 56, respectively. The caging tool 70 comprises an elongated, threaded shaft 71, an end having an enlarged head portion 72. The opposite end of the caging tool 70 is threaded through a nut, head 76 fixedly mounted on the cylindrical head. 48, and has a hexagonal head nut 78 secured securely thereto. The caging tool 70 serves mainly to allow manual retraction of the powerful compression spring 60. The rotation of the hexagonal head nut 78 threads the arrow 71 through the head nut 76, to axially move the clamping tool 70. with respect to the cylindrical head 48. The enlarged head portion 72 slides * freely within the central bore 68 of the spring brake actuator rod 56, but at the same time it is restrained by an inwardly directed annular flange 80 at the proximal end 57 of the actuator rod. In this way, the removal of the caging tool 70 by the rotation of the hexagonal head nut 78 causes the enlarged head portion 72 to abut the annular flange 80, and retracts the pressure plate 58 and compression spring 60. By 'safety, compression spring 60 is typically retracted during repairs to brake actuator 10 and during loading. The cylindrical head 48 includes one or more gates 82 for establishing communication between the first spring brake chamber 62 and the atmosphere. A one-way check valve 90 according to the invention, installed on each gate 82, controls the flow of air through the gate from the first spring brake chamber 62 to the atmosphere. The one-way check valve 90 ventilates air to the atmosphere provided that the pressure differential between the first spring brake chamber 62 and the atmosphere is preferably about two psi (the cracking pressure) to maintain a slight positive pressure in the first spring brake chamber 62. However, the check valve 90 can be designed to operate at any cracking pressure, which varies depending on the particular environment in which the brake actuator is used. spring. Referring to Figure 2, check valve 90 can be seen in greater detail. The check valve 90 has several major components, including a tubular body 92, the first valve 94, the second valve 96, and the support plate 98. The tubular body 92 and the first valve 94 are preferably made of a material Suitable elastomeric and integrally molded as one piece. The Preferred elastomers include, but are not limited to a self-flowering rubber, such as Polydis TR121, sold by Struktol, Inc., which secretes wax. The rubbers tend to prevent the accumulation of paint and ice on the tubular body 92 and the first valve 94 by coating the surface of the elastomer with oil or wax, respectively. The tubular body 92 has an opening 102 extending axially therethrough. The opening 102 begins at an inlet end 104 of the tubular body and ends at one end fluid with the first spring brake chamber 62 so that the compressed fluid within the first spring chamber can flow freely towards the opening 102 of the tubular body 92. In a similar manner, the outlet end 106 is in fluid communication with the atmosphere so that the fluid entering the inlet end 104 can escape into the atmosphere through the outlet end 106. The tubular body 92 further comprises a first radially extending lip 108 disposed around the body circumference tubular 92 near the inlet end 104. In complementary fashion, a second radially extending lip 110 is disposed about the circumference of the tubular body near the outlet end 106. An annular channel 112 is formed between the first and second lips 108. , 110. Preferably, the annular channel 112 is sized to receive loosely the edge of the housing gate 82. A * annular groove 114 is formed in the tubular body 92 and connects with the opening 102. Depending on the application, the annular groove 114 may extend beyond the tubular body 92 and towards the first lip 108. The first valve 94 comprises a or more fins 120, which preferably have a sector shape, formed by one or more slits 130. The fins 120 have an integrally formed stringer 122, which is somewhat trapezoidal in shape, ^ B expanding in width and height from the point of the fin in the form of a sector. The widest and highest portion of the stay 122 is the portion closest to the tubular body 92 and the narrower and lower portion of the stay is closer to an axial centerline of the opening 102. When the tubular body is not assembled in the gate of housing 82, as illustrated in Figure 2, a clearance 124 is present between the tie 122 and the tubular body 92. In the preferred embodiment, the clearance is approximately 15 mils. The fins 120 are pivotally connected to the tubular body 92 by a live hinge 126. The thickness of the hinge 126 is a compromise between providing sufficient material to suitably structurally hold and retain the fin 120 in the tubular body 92 and provide less material to maximize the ease of folding the flap with respect to the tubular body 92. In order to obtain the proper balance between the structural requirements and the bending requirements, an annular groove 128 is formed on the upper surface of the first valve 94 directly on the clearance 124 to control the thickness of Live joint 126. Annular groove 128 reduces the amount of material connecting fin 120 to tubular body 92 and provides an easy way to obtain the proper balance between the material required for structural stability and to pivot the fin. The depth of the annular groove 128 can be varied to obtain the necessary balance for a given application. The second valve 96 comprises an elastomeric disc 140 having multiple recesses 142 formed in the perimetral edge of the elastomeric disc 140. The elastomeric disc 140 has multiple fins 144, which are sector-shaped, formed by slits 146. Preferably, the slits 146 they do not extend to the perimeter of the elastomeric disc. The support plate 98 comprises a metal disc 150, preferably made of stainless steel, such as the elastomeric disc 140, having multiple recesses 152 formed in the perimetral edge of the metal disc 150. Several perforations 154 are formed in the disc 150 The perforations are sector-shaped, like the fins 144. The perforations 154 are preferably somewhat smaller than the fins 144. To assemble the check valve 90, the body tubular 92 is mounted inside the check valve gate by deforming the second lip 110 so that the tubular body and the The second lip can be inserted into the gate of the check valve until the edge of the housing aligns with the annular channel 112. The tubular body 92 is then released from its deformed state and the inherent resilience of the tubular body returns to its original shape. The outer diameter of the tubular body is slightly larger than the inner diameter of the check valve gate so that when the tubular body 92 is inserted into the check valve gate, the tubular body is deformed radially inwardly and fills the free space 124, so that the struts 122 are in contact with the tubular body 92. In this way, the inward deflection of the fins 120 of the first valve 94 is prevented substantially because the tie 122 is in contact with the tubular body 92. However, the fins 120 are still free to pivot up and out in response to the pressurized air exiting through the inlet end 104 of the tubular body. Preferably, the outer diameter of the tubular body is approximately 30 to 40 thousandths of an inch larger than the diameter of the check valve gate 82. The second valve 96 and the support plate 98 are then mounted on the tubular body 92. First, the # perforations 144 of the metal disc 150 are aligned with the fins of the elastomeric disc 140 by aligning the recesses 142, 152 of the metal disc 150 and the elastomeric disc. The elastomeric disc 140 and the aligned metal disc 150 are then inserted into the annular groove 114 of the tubular body 92. The elastomeric disc 140 and the metal disc 150 can be inserted into the annular groove 114 before or after the mounting of the disc. tubular body 92 within the gate of the retaining valve ^^ 82. However, it is preferred that they be mounted in the annular groove after the tubular body 92 is mounted within the check valve gate 82. The elastomeric disc 140 and the metal disc 150 are aligned so that the edges of the fins 144 lie on the portions of the metal disc 150 surrounding the perforations 154. In this manner, the edges of the fins 144 are supported by the metal disc. , which tends to prevent the fins 144 from being drawn into the perforations 154 if a vacuum or low pressure area is formed within the first spring brake chamber 62. In operation, upon release of the brake or spring by the introduction of pressurized fluid towards the second spring brake chamber 63, the second elastomeric diaphragm 52, together with the pressure plate 58, is moved towards the upper part of the housing 48 to reduce the volume of the first camera of spring brake 62 and compress the air inside the chamber. The compression of the air creates a pressure differential between the first spring brake chamber 62 and the atmosphere. When the pressure differential reaches the cracking pressure of the second valve, the fins 144 of the second valve 96 are forced up and out of contact with the metal disk 150. The pressurized air then encounters the fins 120 of the first one. valve 94. When the pressure differential reaches the cracking pressure of the first valve, the fins 120 deflect or pivot upwards, as shown in figure 4. In this state, when both the first and second valves are open, the air under pressure it is free to flow from the first spring brake chamber 62 to the atmosphere. Preferably, the cracking pressure of the first and second valves is approximately the same, but equal cracking pressures are not necessary to practice the invention. As the pressure differential is reduced, the fins 144 of the second valve 96 return to their stop relation with respect to the metal disk 150 and seal the first spring brake chamber 62 with respect to the atmosphere, resulting in the subsequent return of the fins 120 to their sealed positions. Sealing the second valve before the first valve helps prevent the ingress of material into the first spring brake chamber 62 because the air Compressed is still flowing out of the first valve when sealing the second valve. Any material that finds its way through the first valve is trapped between the first and second valves and is ejected when the next air discharge occurs through the check valve. The pivotal movement outwardly of the fins 120 prevents the check valve from being covered by paint. The pressure differential urges the fins 120 outwards to place any layer of paint that covers the fins 120 under tension, which tends to break the paint layer, preventing it from covering the check valve. A positive pressure with respect to the atmosphere is maintained within the first spring brake chamber 62 because the first and second one-way valves seal at a positive pressure slightly less than the cracking pressure. The positive pressure helps to prevent the ingress of material to the valve because the fluid is flowing from the first spring brake chamber 62 to the atmosphere when closing the first and second one way valves, unlike a low pressure or vacuum, which brings material into the first spring brake chamber 62. The formation of low pressure or vacuum in the first spring brake chamber 62 is prevented by the valve 86, which allows the flow of fluid from the second spring brake chamber 63 to the first spring brake chamber 62 when the brakes are applied.

In addition to supporting the elastomeric disc 140, the metal disc 150 provides the independent function of preventing easy removal of the tubular body 92 from the check valve gate 82 after it is installed. The metal disk 150 is dimensioned so that when it is received into the annular groove 114, it stiffens the first lip 108. By stiffening the first lip 108, the check valve is more secure against tampering. The tubular body 92 can not be easily removed from the gate of the check valve 82 due to ^. that the metal disk 150 prevents easy deformation of the first lip 102, which is required for the removal of the tubular body 92. It is preferred that the metal disk 150 has a diameter greater than the diameter of the gate of the check valve 82. However, it is not necessary for the metal disk 150 to have such a diameter in order to provide the necessary stiffening of the first lip 108 to prevent easy removal of the tubular body 92. The metal disk 150 may have a diameter smaller than the diameter of the gate of the check valve 82 and still adequately carry out the stiffening function which is necessary to delay the manipulation of the check valve by pulling it away from the check valve gate. Figure 5 illustrates an alternative embodiment of the check valve 90 according to the invention. The alternative embodiment is substantially identical to check valve 90. Therefore, numbers of Same reference to identify equal parts. The only substantial difference between the check valve illustrated in Figures 1 to 4 and the second check valve embodiment illustrated in Figure 5 is the addition of a duckbill fin 160 comprising a first pick 162 and a second peak 164, between which a narrow rectangular aperture 166 is formed. The duckbill fin is illustrated having a lower annular ring 168, which is press fit securely within an annular recess 170 formed in the second lip 110. Alternatively, the duckbill 160 can be integrally molded with the second lip 110. The duckbill fin reduces the possibility that the accumulation of ice, mud and similar materials on the first valve will cover the first valve. It is also within the scope of the invention to replace the duckbill fin with a hose that is mounted on the check valve in the same manner as the duckbill fin. The hose is of sufficient length to * wrap around the side of the brake housing so that it can not enter the check valve through the hose. Reasonable variations and modifications are possible within the scope of the foregoing description, without departing from the spirit of the invention that is defined in the accompanying claims. For example, the check valve according to the invention can be constructed without the second valve and still carry out the tamper proof function. In this same order of ideas, the check valve can be used without the second valve and the support plate and still provide a solution to the problem of discharging air to the atmosphere while sealing the first spring chamber.

Claims (24)

1. CLAIMS 1. In a brake actuator for a vehicle, comprising: a housing with an actuator rod opening in one end portion and a vent opening in another end portion, the vent opening defined by an edge of the housing; the housing having an interior surface and an exterior surface; a movable member disposed within the housing, the movable member dividing the interior of the housing in a first chamber that includes the end portion mentioned first and a second chamber that includes the other end portion and reciprocally movable therein in response to the delivery and discharge of fluid under pressure to and from the second chamber, respectively; an actuator rod operatively connected to the movable and movable member therewith for operation of a brake, the actuator rod projecting through the actuator rod opening in the first mentioned end portion; a spring disposed in the first chamber in a position for urging the movable member to a first position, wherein the second chamber is collapsed upon the occurrence of pressurized fluid discharge from the second chamber; a passage between the first and second chambers to pass fluid between the two; a valve in the passage between the first and second chambers to allow the flow of fluid from the second to the first chamber but prevent the flow of fluid from the first to the second chamber; and a check valve mounted in the vent opening in the other end portion of the housing for venting fluid in the first chamber when pressurized fluid is supplied to the second chamber to move the movable member toward the other end of the housing to collapse the spring, the improvement comprising: the check valve having: a generally tubular elastomer body having an opening extending therethrough with opposite inlet and outlet ends, the body further having an inner lip and an outer lip, each one separated from the other and extending radially outwardly of the body to define a channel therebetween, and the channel being dimensioned to loosely receive the edge with the inner and outer lips resting against the first and second surfaces, respectively, when the body is received in The opening; a substantially rigid plate having at least one bore and mounted to the body closer to the inner lip and the inlet end and encompassing the opening, said plate having a diameter sized to stiffen a portion of the tubular body; Y a one-way valve disposed near the outer lip and the outlet end of the body to allow fluid flow from the inlet end through the outlet end and inhibit fluid flow from the outlet end through the inlet end; so that when the check valve is mounted within the opening, the plate will prevent removal of the check valve through the opening from the first surface towards the second surface.
2. 2. A brake actuator according to claim 1, wherein the tubular body is made of self-waxing rubber.
3. 3. A brake actuator according to claim 1, and further comprising a second one-way valve that spans the opening and axially disposed between the platen and the first one-way valve.
4. A brake actuator according to claim 3, wherein the second one-way valve is an elastomeric disc having at least one fin.
5. A brake actuator according to claim 4, wherein the at least one fin is aligned with the at least one bore in the plate.
6. A brake actuator according to claim 5, wherein the at least one fin is larger than the at least one perforation and the at least one fin has edges that run into a portion of the plate surrounding the at least one perforation to hold the at least one fin.
7. 7. A brake actuator according to claim 5, wherein the shape of the at least one fin corresponds to the shape of the at least one perforation.
8. A brake actuator according to claim 7, wherein the at least one fin and the at least one perforation are sector-shaped.
9. 9. A brake actuator according to claim 1, wherein the plate has multiple perforations.
10. 10. A brake actuator according to claim 9, wherein the perforations are sector-shaped.
11. A brake actuator according to claim 1, wherein an annular groove is formed in the body in a radially inward position of the inner lip and extends towards the opening and the plate is received in the annular groove to stiffen the lip internal.
12. A brake actuator according to claim 11, and further comprising a second one-way valve that spans the opening and received within the annular groove in an axial position between the platen and the first one-way valve.
13. 13. A brake actuator according to claim 11, wherein the annular groove extends toward the inner lip.
14. 14. A brake actuator according to claim 13, wherein the plate has a diameter larger than the diameter of the opening.
15. 15. A brake actuator according to claim 14, wherein the diameter of the plate is at least equal to the diameter of the annular groove.
16. 16. A brake actuator according to claim 1, wherein the first one-way valve is an elastomeric disc that spans the opening and having at least one fin formed therein to the body to open and close the first one-way valve.
17. 17. A brake actuator according to claim 16, wherein the at least one fin is pivotally mounted on the body.
18. 18. A brake actuator according to claim 17, wherein the at least one fin is pivotally connected to the body by means of a live hinge.
19. 19. A brake actuator according to claim 16, which comprises a strut extending toward the opening and positioned adjacent the body to limit pivotal movement inwardly of the at least one fin.
20. 20. A brake actuator according to claim 16, wherein the first one-way valve has multiple fins.
21. 21. On a brake actuator for a vehicle, which comprising: a housing with an actuator rod opening in one end portion and a vent opening in another end portion, the vent opening defined by an edge of the housing, the housing having an inner surface and an outer surface; a movable member disposed within the housing, the movable member dividing the interior of the housing into a first chamber that includes the other end portion and a second chamber that includes the end portion and reciprocally movable there in response to the delivery and discharge of fluid under pressure to and from the second chamber, respectively; an actuator rod operably connected to the movable and moveable member therewith for operation of a brake, the actuator rod projecting through the actuator rod opening in the end portion; a spring disposed in the first chamber in a position for urging the movable member to a first position where the second chamber is collapsed when the pressurized fluid is discharged from the second chamber; a passage between the first and second chambers to pass fluid between the two; a valve in the passage between the first and second chambers to allow fluid flow from the first to the second chamber but prevent fluid flow from the second to the second chamber. first camera; and a check valve mounted in the vent opening in the other end portion of the housing for venting fluid from the first chamber when pressurized fluid is supplied to the second chamber to move the movable member toward the other end of the housing to collapse the spring, the improvement comprising: the check valve having: a generally tubular elastomer body having an opening extending therethrough with opposite inlet and outlet ends, the body having an inner lip and an outer lip, each spaced apart of the other and extending radially outwardly of the body to define a channel between them, and the channel being dimensioned to loosely receive the edge with the inner and outer lips resting against the inner and outer surfaces, respectively, when the body is received in the opening; a substantially rigid plate having at least one bore and mounted in the body near the inner lip and the inlet end and embracing the opening, said plate having a diameter sized to stiffen a portion of the tubular body; and a one-way valve disposed near the outer lip and the outlet end of the body to allow fluid flow from the inlet end through the outlet end. inhibit flow of fluid from the outlet end through the inlet end; so that when the check valve is mounted inside the opening, the plate will prevent removal of the check valve through the opening from the inner surface towards the outer surface.
22. 22. In a brake actuator for a vehicle, comprising: a housing with an actuator rod opening in one end portion and a vent opening in another end portion, the vent opening defined by an edge of the housing, the housing having an internal surface and an external surface; a movable member disposed within the housing, the movable member dividing the interior of the housing into a first chamber that includes the other end portion and a second chamber that includes the end portion and movable reciprocally therein in response to the delivery and discharge of fluid under pressure to and from the second chamber, respectively; an actuator rod operably connected to the movable and movable member therewith for operation of a brake, the actuator rod projecting through the actuator rod opening in the end portion; a spring disposed in the first chamber in a position for urging the movable member to a first position, where the second chamber is collapsed upon the occurrence of pressurized fluid discharge from the second chamber; a passage between the first and second chambers to pass fluid between the two; a valve in the passage between the first and second chambers to allow fluid flow from the first to the second chamber but prevent the flow of fluid from the second to the first chamber; and a check valve mounted in the vent opening in the other end portion of the housing for venting fluid from the first chamber when pressurized fluid is supplied to the second chamber to move the movable member toward the other end of the housing to collapse the spring, the improvement comprising: the check valve having: a generally tubular elastomer body having an opening extending therethrough with opposite inlet and outlet ends, the body further having an inner lip and an outer lip, each separated from the other and extending radially outward from the body to define a channel between them, and the channel being dimensioned to loosely receive the edge with the inner and outer lips supporting against the inner and outer surfaces, respectively, when the body is received in the opening, a first one-way valve "arranged near the end of body outlet to allow fluid flow from the inlet end through the outlet end and inhibit the flow of fluid from the outlet end through the inlet end; and a second one-way valve mounted near the outlet end of the body to provide discharge of a fluid passing through the first one way valve. through the exit end.
23. 23. In a brake actuator for a vehicle, comprising: a housing with an actuator rod opening in one end portion and a vent opening in another end portion, the vent opening defined by an edge of the housing; the housing having an interior surface and an exterior surface; a movable member disposed within the housing, the movable member dividing the interior of the housing in a first chamber that includes the end portion mentioned first and a second chamber that includes the other end portion and reciprocally movable therein in response to the delivery and discharge of fluid under pressure to and from the second chamber, respectively; An actuator rod operatively connected to the movable and movable member therewith for operation of a brake, the actuator rod projecting through the opening of the actuator. actuator stem in the first mentioned end portion; a spring disposed in the first chamber in a position for urging the movable member to a first position, wherein the second chamber is collapsed upon the occurrence of pressurized fluid discharge from the second chamber; a passage between the first and second chambers to pass fluid between the two; a valve in the passage between the first and second chambers to allow fluid flow from the first to the second chamber but prevent the flow of fluid from the second to the first chamber; and a check valve mounted in the vent opening in the other end portion of the housing for venting fluid in the first chamber when pressurized fluid is supplied to the second chamber to move the movable member toward the other end of the housing to collapse the spring, the improvement comprising: the check valve having: a generally tubular elastomer body having an opening extending therethrough with opposite inlet and outlet ends, the body further having an inner lip and an outer lip, each one separated from the other and extending radially outward from the body to define a channel between them, and the channel being dimensioned to loosely receive the edge with the inner and outer lips supporting against the first and second surfaces, respectively, when the body is received in the opening; and a one-way valve disposed near the outlet end of the body to allow fluid flow from the inlet end through the outlet end and inhibit fluid flow from the outlet end through the inlet end, the one-way valve comprising an elastomeric disc that spans the opening and has at least one tab formed there and movably mounted on the body to open and close the one-way valve, and the at least one wing having a tie extending to the opening and placed adjacent to the body to limit the pivotal movement inward of the fin.
24. 24. A check valve adapted to be mounted on a structural member having first and second opposed surfaces and an opening extending therethrough defined by an edge, the check valve comprising: a generally tubular elastomeric body having an opening that it extends through it with opposite ends of entry and exit, the body having also an inner lip and an outer lip, each separated from the other and extending radially outward from the body to define a channel between them, and the channel being dimensioned to receive comfortably the edge with the inner and outer lips resting against the first and second surfaces, respectively, when the body it is received in the opening; a substantially rigid plate having at least one bore and mounted in the body closer to the inlet end and encompassing the opening, said plate having a diameter sized to stiffen a portion of the tubular body near the inner lip; and a one-way valve disposed closer to the outlet end of the body to allow fluid flow from the inlet end through the outlet and inhibit the flow of fluid from the outlet end through the inlet end; so that when the check valve is mounted within the opening, the plate will prevent removal of the check valve through the opening from the first surface towards the second surface.