RESET VALVE FOR COMPRESSION RELEASE BRAKE

Abstract

An engine brake reset valve includes a cylindrical housing body having an end and a central cavity therein. The reset valve includes a first valve part attached to a second valve part, wherein the central cavity is sized to receive the first valve part and the second valve part. The first and second valve parts are movable within the central cavity between open and closed positions. When the second valve part is in a closed position, the second valve part engages and blocks the central orifice to prevent fluid pressure from entering the central orifice. When the second valve part is in an open position, the second valve part moves away from the central orifice to enable fluid pressure to enter the central orifice.

Description

TECHNICAL FIELD

The present application relates generally to an exhaust valve opening apparatus such as for compression release braking or early exhaust valve opening operations, and more particularly to a reset valve for a compression release brake.

BACKGROUND

Exhaust valve opening devices are used for compression braking for heavy vehicles and for early exhaust valve opening for combustion and thermal management. For example, compression braking converts an internal combustion engine cylinder to a compressor by opening an exhaust valve of the cylinder near the end of the compression stroke. This allows the power generated in the piston to escape to the atmosphere rather than continuing to power the crankshaft of the vehicle, and the use of service brakes can be minimized, extending their life. Moreover, the escape of the power generated in the piston to the atmosphere avoids overheating of service brakes.

Exhaust valve opening devices used for compression braking forms an engine braking function that relies on a high pressure hydraulic linkage between primary and secondary pistons. In one form, when a supply oil pressure is high, a retaining spring on the piston is overcome by the supply oil pressure causing the oil volume in the high pressure circuit to build up or increase. Over time, this increase in supply oil pressure can cause the secondary piston to track the exhaust valve motion during the exhaust valve motion during the exhaust stroke resulting in a jacking effect where the secondary piston progressively fails to return to its initial position during every braking cycle. This condition is potentially dangerous as the incomplete closure of the exhaust valve can result in valve to piston contact and catastrophic failure of the engine. Several solutions exist to mitigate this concern including utilizing a stiffer retention spring and including a pressure regulation device in the circuit. However, these solutions require additional packaging volume which may not always exist in the design. Therefore, further improvements in this area of technology are desired.

SUMMARY

A unique reset valve for a compression release brake prevents jacking of secondary pistons and facilitates exhaust valves closing during a main exhaust event. The reset valve for a compression release brake also prevents exhaust valve to piston contact. The reset valve for a compression release brake is positioned in a high pressure brake circuit to bleed oil or fluid pressure when the primary piston returns to the base circle of the cam lobe. The reset valve for a compression release brake enables an engine brake system to tolerate a higher oil supply pressure and enables the engine brake system to be less sensitive to supply pressure variation.

The reset valve disclosed herein is also beneficial when an overall engine package size constraint does not permit the use of a pressure relief valve in the oil supply circuit. The reset valve is also beneficial when the engine package size constraint does not permit the use of a stiffer retaining spring.

This summary is provided to introduce a selection of concepts that are further described below in the illustrative embodiments. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The concepts described herein are illustrative by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, elements illustrated in the figures are not necessarily drawn to scale. Where considered appropriate, references labels have been repeated among the figures to indicate corresponding or analogous elements.

FIG. 1 is a schematic illustration of an embodiment of an exhaust valve opening system according to the present disclosure.

FIG. 2 is an exploded perspective view of the exhaust valve opening system of FIG. 1.

FIG. 3 is an exploded perspective view of a rocker lever assembly of the exhaust valve opening system of FIG. 1.

FIG. 4 is an exploded perspective view of a cam housing assembly of the exhaust valve opening system of FIG. 1.

FIG. 5 is a schematic illustration of the fluid flow paths through a rocker shaft of the exhaust valve opening system of FIG. 1 to supply control fluid to the cam housing assembly.

FIG. 6 is a schematic illustration of the fluid flow paths in the cam housing assembly of the exhaust valve opening system of FIG. 1 to receive control fluid from the rocker shaft of FIG. 5 and supply control fluid to the various components of the cam housing assembly.

FIGS. 7A and 7B are cross-sectional views of a check valve of the exhaust valve opening system of FIG. 1.

FIG. 8 is a first cross-sectional view of an engine brake reset valve of the exhaust valve opening system of FIG. 1.

FIG. 9 is a second cross-sectional view of the engine brake reset valve of FIG. 8.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, any alterations and further modifications in the illustrated embodiments, and any further applications of the principles of the invention as illustrated therein as would normally occur to one skilled in the art to which the invention relates are contemplated herein.

Turning now to the present application with reference to FIG. 1, is an embodiment of an exhaust valve opening system 100 that includes a control fluid supply 102 that is operable to supply a control fluid to a first cam housing part 110a and a second cam housing part 110b to open first and second exhaust valves 114a, 114b. In particular, when enabled by system 100, cam lobes 118a, 118b act on the roller followers 116a, 116b of the first and second primary pistons 120a, 120b to displace respective first and second secondary pistons 122a, 122b that are connected respective ones of the first and second exhaust valves 114a, 114b, thus opening and closing the exhaust valves 114a, 114b.

System 100 includes a controllable valve 112, such as a solenoid valve, that is mounted to a rocker shaft 104 and receives the control fluid from a passage of the rocker shaft 104, which is fluidly connected to the control fluid supply 102. The controllable valve 112 is operable to pressurize the control fluid and provide the control fluid, through another passage of the rocker shaft 104, to first check valve 124a of the first cam housing part 110a and, through the passage of the rocker shaft 104, to a second check valve 124b of the second cam housing part 110b.

First check valve 124a receives the pressurized control fluid from controllable valve 112 via the rocker shaft 104 and prevents reverse flow so that in response to the cam lobe 118a displacing the first primary piston 120a, a corresponding displacement of first secondary piston 122a is provided that opens first exhaust valve 114a. Second check valve 124b receives the pressurized control fluid from controllable valve 112 via the rocker shaft 104 and prevents reverse flow so that in response to the cam lobe 118b displacing the second primary piston 120b, a corresponding displacement of the second secondary piston 122b is provided that opens second exhaust valve 114b.

Referring to FIG. 2, the exhaust valve opening system 100 includes a rocker lever assembly 130 that houses the rocker levers of the engine along with rocker shaft 104. Exhaust valve opening system 100 further includes a cam housing assembly 150 that includes a cam housing 154 for housing a cam shaft 152 that carries the cam lobes 116a, 116b. Exhaust valve opening system 100 also includes a cylinder head assembly 170 that is mountable to the engine block to support first and second exhaust valves 114a, 114b, along with the intake valves and other components, in the desired configuration relative to the respective engine cylinders.

Referring to FIG. 3, rocker lever assembly 130 is shown with controllable valves 112, one of which is in an exploded view. Controllable valves 112 are mounted to rocker shaft 104 so that each controllable valve 112 is spaced along rocker shaft 104 and is associated with a respective pair of exhaust valves 114a, 114b of a pair of cylinders. In one embodiment, a valve housing 132 is fastened to rocker shaft 104 with a fastener 134 in hole 140 of rocker shaft 104 between rocker levers 144, 146. Embodiments without a valve housing 132 are also contemplated. As discussed further below, rocker shaft 104 includes flow passages to provide control fluid to and from controllable valve 112. Valve housing 132 includes a receptacle 138 to receive controllable valve 112. Each controllable valve 112 also includes a wiring harness 136 for engagement to a control system that provides signal to activate and deactivate controllable valve 112 to selectively supply pressurized control fluid.

Referring to FIG. 4, cam housing assembly 150 is shown with check valve 124a, primary piston 120a, and secondary piston 122a in an exploded view. First primary piston 120a is engaged in a first receptacle 156 of cam housing 154, such as shown with second primary piston 120b. As described in FIGS. 8 and 9, end 121a of primary piston 120a includes a first roller or other member 802a to contact the cam lobe 116a. When the control fluid is de-energized, the primary piston 120a is configured to collapse in response to passage of the cam lobe 116a there against, but is configured to be locked by the control fluid to prevent collapse when exhaust valve opening is desired. First secondary piston 122a is engaged in a second receptacle 158 of cam housing 154, such as shown with second secondary piston 122b. First check valve 124a is engaged in third opening 160 of cam housing 154, such as shown with second check valve 124b.

FIG. 5 shows a schematic of the arrangement of the control fluid delivery circuit to check valves 124a, 124b via rocker shaft 104. Rocker shaft 104 includes a controllable valve flow path 106 and a check valve flow path 108, each extending longitudinally through rocker shaft 104 with transverse portions to provide the necessary flow path connections. Controllable valve flow path 106 is connected at point AA to control fluid supply 102 to provide the control fluid to controllable valve 112 at inlet BB.

In response to a command or operation of open the exhaust valves 114a, 114b, controllable valve 112 is energized to pressurize the control fluid. Controllable valve 112 includes an outlet CC that is connected to check valve flow path 108 at point DD in rocker shaft 104. Check valve flow path 108 extends to and is connected to first check valve 124a at point EE and to second check valve 124b at point FF to deliver pressurized control fluid to the check valves 124a, 124b mounted to the cam housing 154.

Referring to FIG. 6, the flow path in the cam housing 154 for one check valve 124a is shown, it being understood the flow paths in cam housing 154 for the other check valves can be similarly configured. Cam housing 154 receives control fluid from rocker shaft 104 at inlet GG to the check valve 124a. Pressurized control fluid exits check valve 124a and is provided to primary cylinder 120a at point HH. Pressurized control fluid is further provided from primary cylinder 120a at an outlet II to a cam housing flow passage 170. Cam housing flow passage 170 extends longitudinally to provide control fluid to an inlet JJ of secondary piston 122a. When controllable valve 112 is de-energized, control fluid can bleed back through check valve 124a at bleed outlet KK to allow the exhaust valves 114a, 114b to rapidly close.

FIGS. 7A-7B show an embodiment of check valves 124a, 124b that is configured to allow pressurized control fluid to bleed back there through in response to controllable valve 112 being de-energized. This embodiment check valve includes a cylindrical housing body 180 with a central cavity for housing a spring 182, a first valve part 184, and a second valve part 186. First valve part 184 includes a recessed side hole(s) 194 there through. Housing body 180 includes an inlet 188 at one end thereof and an outlet 190 at the opposition end thereof. Housing body 180 further includes at least one hole 192 in the side thereof.

In FIG. 7B check valve 124a, 124b is opened since pressurized control fluid compresses spring 182 to unseat first valve part 184 from inlet 188 and unseat second valve part 186 from end opening 196 of first valve part 184. This allows control fluid to flow into the cavity of housing body 180, through the end opening 196 of first valve part 182, and out of the aligned holes 192, 194 to the primary piston 120a. The outlet 190 of housing body 180 is simultaneously closed by second valve part 186.

In FIG. 7A the controllable valve 112 is de-energized and the control fluid is not actively pressurized, allowing first valve part 184 to seat against housing body 180 and second valve part 186 to seat against end opening 196 via spring 182, preventing control fluid from entering housing body 180. However, hole 192 is only partially obstructed by first valve part 184, allowing fluid to flow back into the housing cavity through hole 192 and through the outlet 190, allowing the pressure from the control fluid to bleed from primary piston 120a to the oil sump so that the exhaust valve is no longer opened by the exhaust valve opening system 100.

Turning now to FIGS. 8 and 9, are cross-sectional views of the cam housing 154 that includes the first primary piston 120a and an engine brake reset valve 800a. The second primary piston 120b is similar to the first primary piston 120a, therefore is not described. As described above, when enabled by system 100, cam lobe 116a of the corresponding cam shaft 118a acts on the first primary piston 120a to displace the first secondary piston 122a that is connected to the first exhaust valve 114a thus opening and closing the exhaust valve 114a. The engine brake reset valve 800a is configured to allow control fluid pressure to bleed therethrough in response to the first primary piston 120a being on cam lobe 116a base circle.

The end 121a of cam housing 154 includes a central cavity 123a sized to receive the primary piston 120a and engine brake reset valve 800a. The central cavity 123a is also sized to receive a first roller or other member 802a to contact the cam lobe 116a. When the control fluid is de-energized, the first primary piston 120a is configured to collapse in response to passage of the cam lobe 116a there against, but is configured to be locked by the control fluid to prevent collapse when opening of exhaust valve 114a is desired.

The first primary piston 120a assembly includes a cylindrical housing body 803a that includes an end 805a and a central cavity 807a therein. The central cavity 807a is sized to receive a first spring 806a arranged to continuously apply pressure relative to movement of the cam lobe 116a against the first primary piston 120a. When the cam lobe 116a rotates such that the base circle of the cam shaft 118a is positioned next to the piston 120a, the cam lobe 116a has moved away from the first spring 806a thereby enabling or releasing the first spring 806a to push or engage the first primary piston 120a towards the base circle of the cam shaft 118a.

The central cavity 807a is further sized to receive a first valve part 824a, a second valve part 826a, a second spring 828a, a first primary piston crown 830a, and a first primary piston body 832a. The first valve part 824a is connected or monolithic with a second valve part 826a. The first valve part 824a has a length sufficient to receive the second spring 828a on a first portion of the length. The first valve part 824a has a length sufficient to engage or fit in a through-hole 836a of the first primary piston crown 830a via a second portion of the length. In the illustrated embodiment, the first valve part 824a is cylindrical in shape but may have different cross-sectional shapes in other embodiments. The first valve part 824a includes a recessed side hole(s) 840a there through configured to receive a retention clip 834a at or near an end 838a of the first valve part 824a for engagement with the first primary piston crown 830a. The retention clip 834a is configured to retain the first valve part 824a assembled to the first primary piston crown 830a.

The second valve part 826a is a check ball with a spherical shape but may have different shapes in other embodiments. The second valve part 826a is sized to engage and block a central orifice 820a in the cylindrical housing body 803a to prevent fluid or oil pressure from entering the central orifice 820a. When the base circle of the cam shaft 118a is positioned next to the first primary piston 120a, the engine brake reset valve 800a is open such that the second valve part 826a is open or away from the central orifice 820a to enable bleeding of control fluid pressure from the high pressure oil circuit between the first primary piston 120a and the first secondary piston 122a through the central orifice 820a and the lateral orifice 822a which prevents motion transfer from the first primary piston 120a to the first secondary piston 122a. When the first primary piston 120a begins to move, the engine brake reset valve 800a closes such that the second valve part 826a closes or seals the central orifice 820a to prevent oil pressure from bleeding to thereby maintain the oil pressure in the high pressure oil circuit between the first primary piston 120a and the first secondary piston 122a and allow or enable motion transfer to the first secondary piston 122a.

The first primary piston crown 830a includes a cylindrical portion 841a that receives a through-hole 839a therein that is sized to receive the first valve part 824a and assembly of the retention clip 840a to retain the first valve part 824a with the first primary piston crown 830a. The cylindrical portion 841a extends to a flared portion 844a that includes a portion of the through-hole 839a for receipt of a portion of the second spring 828a.

The first primary piston body 832a includes a cylindrical portion 851a that receives a through-hole 842a therein that is sized to receive and retain the cylindrical portion 841a of the first primary piston crown 830a therein. The cylindrical portion 851a of the first primary piston body 832a is sized to receive the first spring 806a thereon. The first primary piston body 832a includes a through-hole 842a that extends the length of the first primary piston body 832a. The cylindrical portion 851a extends to a flared portion 854a that includes an opening 856a that opens or connects to the through-hole 842a. The opening 856a is sized to receive a portion of the first roller 802a therein. The first spring 806a is sized to fit on an outer surface of the cylindrical portion 851a.

The first roller 802a is rotatably mounted on a first pin 804a wherein the first roller 802a is rolling or rotating about the first pin 804a as the cam lobe 116a engages the first roller 802a. To push the first primary piston 120a open, the cam lobe 116a pushes on or against the first roller 802a which moves the first primary piston 120a in the direction of arrow 808a.

The cylindrical housing body 803a includes a central orifice 820a fluidly connected to a lateral orifice 822a. The orientation of the lateral orifice 822a to the central orifice 820a can vary in other embodiments. For example, the lateral orifice 822a may be perpendicular to the central orifice 820a or may have a non-perpendicular arrangement. The central and lateral orifices 820a and 822a are configured to drain excess fluid or oil pressure when the second valve part 824a moves away from the central orifice 820a to thereby expose the central orifice 820a.

In some embodiments, the cylindrical housing body 803a includes a pressure tap 860a that is a small hole in the cylindrical housing body 803a that can receive fluid pressure.

In FIG. 8, the engine brake reset valve 800a is open such that the second valve part 826a or check ball is in an open position when the base circle of the cam shaft 118a is positioned next to the first primary piston 120a. The cam lobe 116a has moved away from the first spring 806a thereby enabling or releasing the first spring 806a to push or engage the first primary piston 120a towards the base circle of the cam shaft 118a. The second valve part 826a is open or away from the central orifice 820a to enable bleeding of control fluid or oil pressure from the high pressure oil circuit between the first primary piston 120a and the first secondary piston 122a through the central orifice 820a and the lateral orifice 822a which prevents motion transfer from the first primary piston 120a to the first secondary piston 122a. The excess control fluid pressure from the high pressure circuit bleeds through the central orifice 820a and then through the lateral orifice 822a.

In FIG. 9, when the cam shaft 118a rotates such that the cam lobe 116a engages the first primary piston 120a to force the first primary piston 120a and the first and second valve parts 824a and 826a to move toward the central orifice 820a, the engine brake reset valve 800a closes such that the second valve part 826a closes or seals the central orifice 820a to prevent oil pressure from bleeding therein. The first and second valve parts 824a and 826a move towards the central orifice 820a to close or seal the central orifice 820a and maintain the oil pressure in the high pressure oil circuit between the first primary piston 120a and the first secondary piston 122a which allows or enables motion transfer to the first secondary piston 122a. The fluid or oil pressure is sealed in the high pressure circuit between the first primary and secondary pistons 120a and 122a.

The engine brake reset valve 800a is designed to open when the first primary piston 120a is on base circle of the cam 118a, allowing the high pressure to bleed through the central and lateral orifices 820a and 822a. When the first primary piston 120a begins to move, the engine brake reset valve 800a closes thereby maintaining pressure in the high pressure circuit to lift the first secondary piston 122a and first exhaust valve 114a. The bleed path through the central and lateral orifices 820a and 822a occurs each cycle that the cam lobe 116a rotates such that excess pressure is eliminated or released through the central and lateral orifices 820a and 822a. As such, the first secondary piston 122a returns to its initial position during braking cycles and the potential for jacking is eliminated.

Various aspects of the present application are contemplated. According to one aspect, an engine brake reset valve comprising: a cylindrical housing body having an end and a central cavity therein; a first valve part attached to a second valve part, wherein the central cavity is sized to receive the first valve part and the second valve part, the first and second valve parts are movable within the central cavity between open and closed positions; wherein the cylindrical housing body defines a central orifice, when the second valve part is in a closed position the second valve part engages and blocks the central orifice to prevent fluid pressure from entering the central orifice, when the second valve part is in an open position the second valve part moves away from the central orifice to enable fluid pressure to enter the central orifice.

In one embodiment, further comprising: a first spring positioned in the central cavity, the first spring arranged to apply pressure relative to movement of a cam lobe against a first primary piston.

In one embodiment, further comprising: a second spring positioned on the first valve part.

In one embodiment, further comprising: wherein the cylindrical housing body defines a lateral orifice fluidly connected to the central orifice.

In one embodiment, further comprising: a piston crown operably assembled with a piston body positioned in the central cavity, wherein the piston crown includes a cylindrical portion that defines a through-hole therein that is sized to receive the first valve part.

In one embodiment, wherein the first valve part includes a retention clip to retain the first valve part assembled with the piston crown.

In one embodiment, wherein the piston body includes a cylindrical portion that defines a through-hole therein that is sized to receive and retain the cylindrical portion of the piston crown therein.

In one embodiment, wherein the second valve part is spherical in shape.

A first primary piston comprising the engine brake reset valve of any of the embodiments.

In the above description, certain relative terms may be used such as “up,” “down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” “proximal,” “distal,” and the like. These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships. But, these terms are not intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an “upper” surface can become a “lower” surface simply by turning the object over. Nevertheless, it is still the same object.

Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. Similarly, the use of the term “implementation” means an implementation having a particular feature, structure, or characteristic described in connection with one or more embodiments of the present disclosure, however, absent an express correlation to indicate otherwise, an implementation may be associated with one or more embodiments.

The described features, structures, advantages, and/or characteristics of the subject matter of the present disclosure may be combined in any suitable manner in one or more embodiments and/or implementations. In the following description, numerous specific details are provided to impart a thorough understanding of embodiments of the subject matter of the present disclosure. One skilled in the relevant art will recognize that the subject matter of the present disclosure may be practiced without one or more of the specific features, details, components, materials, and/or methods of a particular embodiment or implementation. In some instances, the benefit of simplicity may provide operational and economic benefits and exclusion of certain elements described herein is contemplated as within the scope of the invention herein by the inventors to achieve such benefits. In other instances, additional features and advantages may be recognized in certain embodiments and/or implementations that may not be present in all embodiments or implementations. Further, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the subject matter of the present disclosure. The features and advantages of the subject matter of the present disclosure will become more fully apparent from the following description and appended claims, or may be learned by the practice of the subject matter as set forth hereinafter.

The present subject matter may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. An engine brake reset valve comprising: a cylindrical housing body having an end and a central cavity therein;a first valve part attached to a second valve part, wherein the central cavity is sized to receive the first valve part and the second valve part, the first and second valve parts are movable within the central cavity between open and closed positions;wherein the cylindrical housing body defines a central orifice, when the second valve part is in a closed position the second valve part engages and blocks the central orifice to prevent fluid pressure from entering the central orifice, when the second valve part is in an open position the second valve part moves away from the central orifice to enable fluid pressure to enter the central orifice.

2. The engine brake reset valve of claim 1, further comprising: a first spring positioned in the central cavity, the first spring arranged to apply pressure relative to movement of a cam lobe against a first primary piston.

3. The engine brake reset valve of claim 1, further comprising: a second spring positioned on the first valve part.

4. The engine brake reset valve of claim 1, further comprising: wherein the cylindrical housing body defines a lateral orifice fluidly connected to the central orifice.

5. The engine brake reset valve of claim 1, further comprising: a piston crown operably assembled with a piston body positioned in the central cavity, wherein the piston crown includes a cylindrical portion that defines a through-hole therein that is sized to receive the first valve part.

6. The engine brake reset valve of claim 5, wherein the first valve part includes a retention clip to retain the first valve part assembled with the piston crown.

7. The engine brake reset valve of claim 5, wherein the piston body includes a cylindrical portion that defines a through-hole therein that is sized to receive and retain the cylindrical portion of the piston crown therein.

8. The engine brake reset valve of claim 1, wherein the second valve part is spherical in shape.

9. A first primary piston comprising the engine brake reset valve of claim 1.