ENGINE BRAKE SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

Abstract

An engine braking system includes a housing having a first passage extending along a first axis, a second passage extending along a second axis intersecting the first axis, the first passage communicating with the second passage. The engine braking system further includes a pintle disposed in the first passage and configured to translate along the first axis to hold one or more valves of an internal combustion engine open, a wedge disposed in the second passage and configured to translate along the second axis and engage the pintle, and a solenoid coupled to the wedge and configured to actuate the wedge along the second axis.

Description

INTRODUCTION

[0001] The present invention relates generally to internal combustion engines and in particular to an engine braking system according to the preamble of claim 1 for internal combustion engines, as is essentially known from DE 11 2009 002 211 B4.

[0002] Further state of the art can be found in DE 11 2021 007 080 T5.

[0003] Internal combustion engines typically utilize mechanical, electrical, or hydromechanical valve actuation systems to control the flow of combustible components, typically fuel and air, to one or more combustion chambers during operation. Such systems control the movement and timing of intake and exhaust valves during engine operation and may include a combination of camshafts, cam followers, rocker arms, valve rods, and other elements (such elements together forming a valve train) driven by a rotating engine crankshaft. The timing of valve actuation may be determined by the size and location of the camshaft lobes.

[0004] During positive power production of internal combustion engines, the engine sequentially completes an intake stroke, a compression stroke, an expansion or power stroke, and then an exhaust stroke for each full revolution (i.e., 360 degrees) of the camshaft. During the intake stroke, the intake valves are open to admit fuel and / or air into a cylinder for combustion. During the compression stroke, both the exhaust and intake valves are closed to allow compression of the air-fuel mixture by a piston in the combustion chamber. While the compressed air / fuel mixture explodes, the exhaust and intake valves remain closed, forcing the piston downward in the expansion or power stroke. During the exhaust stroke, the exhaust valves are subsequently opened to allow combustion products to escape from the cylinder.

[0005] Vehicles may be equipped with a compression release brake to help slow vehicles while driving. Generally, the compression release brake is configured to open exhaust valves to cylinders just before the compression stroke ends, releasing any compressed gas that may be trapped in the cylinders. Existing systems are complex and rely on hydraulics to actuate the compression release brake and to keep one or more exhaust valves open during an engine braking event. One or more aspects of the present invention address disadvantages of existing systems. SUMMARY

[0006] According to the invention, an engine braking system, also referred to here as an engine brake, is presented, which is characterized by the features of claim 1.

[0007] The engine brake system includes a housing having a first passage extending along a first axis and a second passage extending along a second axis intersecting the first axis. The first passage communicates with the second passage. The engine brake further includes a pintle disposed in the first passage and configured to translate along the first axis to hold one or more valves of an internal combustion engine open, a wedge disposed in the second passage and configured to translate along the second axis and engage the pintle, and a solenoid coupled to the wedge and configured to actuate the wedge along the second axis.

[0008] The engine brake may include one or more of the following optional aspects. For example, the housing may further include a main body defining the first passage and the second passage, and a base extending from the main body and including one or more fastener holes.

[0009] According to at least one aspect, the pintle may be movable between a first pintle position and a second pintle position relative to the first axis. The pintle may be disengaged from the one or more valves of the internal combustion engine in the first pintle position, and the pintle may be engaged with the one or more valves in the second pintle position.

[0010] In another aspect, the engine brake may further include a valve bridge disposed between the pintle and the one or more valves of the internal combustion engine.

[0011] According to at least one example, the wedge may be movable between a first wedge position and a second wedge position.

[0012] In at least one aspect, the engine braking system is self-locking when the wedge leaves the first wedge position and when the pin leaves the first pin position.

[0013] In at least one aspect, the second passage may further include a first lip and a second lip extending toward each other along a third axis intersecting the first and second axes, the first lip and the second lip defining a first channel and a second channel. The wedge may further include a guide portion configured to translate within the first channel along the first lip and the second lip, and an actuating surface extending into the second channel and configured to contact the stud.

[0014] According to another aspect, the second passage may define a cylindrical channel. The wedge may further include a cylindrical body having a first end and a second end opposite the first end. The wedge may include a chamfered portion between the first end and the second end defining an actuation surface that may be configured to contact the pin.

[0015] An internal combustion engine is also described. It includes a cylinder head having one or more passages and one or more fastener openings, and a valve train coupled to the cylinder head, which includes one or more intake valves, one or more exhaust valves, and one or more rocker arms coupled to the one or more intake valves and to the one or more exhaust valves.The internal combustion engine further includes an engine brake coupled to the cylinder head and disposed with respect to the one or more exhaust valves, including a housing having a main body including a first passage extending along a first axis and a second passage extending along a second axis, a pintle disposed in the first passage and configured to translate along the first axis to maintain the one or more exhaust valves open, a wedge disposed in the second passage and configured to translate along the second axis and engage the pintle, and a solenoid coupled to the wedge and configured to actuate the wedge along the second axis.

[0016] The internal combustion engine may include one or more of the following optional aspects. For example, the pintle may be movable between a first pintle position and a second pintle position relative to the first axis. The pintle may be disengaged from the one or more exhaust valves in the first pintle position, and the pintle may be engaged with the one or more exhaust valves in the second pintle position. Further, the internal combustion engine may include a valve bridge disposed between the pintle and the one or more exhaust valves.

[0017] According to another aspect, the wedge may be movable between a first wedge position and a second wedge position. When the wedge leaves the first wedge position and when the pin leaves the first pin position, the engine brake may be self-locking.

[0018] According to at least one example, the wedge may further include a first end and a second end opposite the first end with respect to the second axis, and a chamfered portion axially disposed between the first end and the second end.

[0019] According to another configuration, an engine braking system is provided and includes a housing containing a first passage and a second passage. The engine braking system further includes a pintle disposed in the first passage and configured to translate it between a first pintle position and a second pintle position, a wedge disposed in the second passage and configured to translate it between a first wedge position and a second wedge position, and a solenoid coupled to the wedge and configured to actuate the wedge between the first wedge position and the second wedge position. When the wedge leaves the first wedge position, the engine braking system may be self-locking. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described here are for illustrative purposes only and show selected configurations; they show: Fig. 1 is a perspective view of an engine braking system disposed on a cylinder head of an internal combustion engine in accordance with principles of the present invention; Fig. 2 a perspective view of the engine braking system Fig. 1; Fig. 3 a side view of the engine braking system Fig. 2, which shows a rectangular wedge disposed in a passage according to the principles of the present invention; and Fig. 4 is a side view of another configuration of an engine braking system showing a circular wedge disposed in a passageway in accordance with the principles of the present invention.

[0021] Corresponding reference symbols designate corresponding parts throughout the drawings. DETAILED DESCRIPTION

[0022] Engine braking may be desired to relieve cylinder pressure via an exhaust valve during a compression stroke of a four-stroke internal combustion engine. In doing so, the engine 10 may enter an engine braking mode, which includes reducing the energy output of the engine 10, drag on rotating and reciprocating components of the engine 10, and energy loss from wheel friction. In accordance with principles of the present invention, an engine brake is provided configured to engage the exhaust valve during the compression stroke of the engine cycle. Typically, there are about 5 to 12 milliseconds in which the exhaust valve is at or above a desired lift necessary to ensure engine braking. As discussed in detail below, the engine brake may be coupled to an actuating mechanism (e.g.,a solenoid) to keep one or more exhaust valves open during one or more engine cycles.

[0023] Based on Fig. 1, a portion of an internal combustion engine (hereinafter engine) 10 is shown. The engine 10 includes a cylinder head 12 and a valvetrain 14 disposed on and / or coupled to the cylinder head 12. The cylinder head 12 includes one or more passages 16 and one or more fastener openings 18. The valvetrain 14 may be configured to control operation of one or more intake valves 20 and one or more exhaust valves 22. More specifically, the valvetrain 14 may include one or more rocker arms 24 for operating the valves 20, 22. The one or more rocker arms 24 may include a pushrod 26 coupled at one end to a tappet 28 and at the other end to a rocker arm 30. The rocker arm 30 can be coupled directly or indirectly (e.g. via a valve bridge 32) to one or more exhaust valves 22 or intake valves 20.A camshaft (not shown) may be arranged to rotate relative to and contact the lifters 28 of the rocker arms 24 to control the opening and / or closing of the valves 20, 22. The rocker arms 24 may also include one or more valve springs 34 that may facilitate the closing of the intake and exhaust valves 20, 22.

[0024] Further, the engine 10 may include an engine control module that includes one or more subcontrollers, such as an engine braking controller 36. As discussed in more detail below, the engine braking controller 36 may be configured to communicate with and control the operation of an engine braking system 100 disposed on and / or coupled to the cylinder head 12.

[0025] As in Fig. 1 and Fig. 2, the engine braking system 100 may be disposed above the valve bridge 32. According to other configurations, the engine braking system 100 may be disposed toward an outer portion of the exhaust valves 22 or directly above the exhaust valves 22.

[0026] Continue with Fig. 2, the engine braking system 100 includes a housing 110 with a main body 111. The main body 111 may include a first passage or pintle passage 112 running along a first axis 38 and a second passage or key passage 113 running along a second axis 40 intersecting the first axis 38. For example, the first axis 38 and the second axis 40 may form an angle between 70 and 90 degrees. According to the present illustrative example, the first passage 112 is in communication with the second passage 113. The housing 110 may be configured to position one or more components of the engine braking system 100 with respect to the one or more exhaust valves 22 and / or the valve bridge 32. The housing 110 may include a base 114 coupled to the main body 111 and containing one or more fastener holes 115. As shown in Fig. 2, one or more bolts 116 may be disposed through the one or more fastener holes 115 and coupled to the one or more fastener openings 18 of the cylinder head 12. In accordance with at least one aspect of the present invention, the bolts 116 may be selected and / or configured to withstand braking loads from the valve springs 34 and / or a built-up exhaust pressure of one or more cylinders (not shown) of the engine 10.

[0027] Based on Fig. 3, the first passage 113 may include a first lip 117a and a second lip 117b extending toward each other along a third axis 42 intersecting the first axis 38 and the second axis 40. Furthermore, the second passage 113 may include a first channel 118a and a second channel 118b defined by the first and second lips 117a, 117b. According to another configuration of the housing 110', the second passage 113' may be defined by Fig. 4 be defined by a cylindrical opening or a cylindrical channel 119.

[0028] Again based on Fig. 2, the engine braking system 100 includes a pintle 120 disposed along the first axis 38 within the housing 110. The pintle 120 may include a first end 121 extending into a portion of the second passage 113 and a second end 122 opposite the first end 121 with respect to the first axis 38. The pintle 120 may be configured to translate along the first axis 38 such that the second end 122 may extend beyond the housing 110 and engage the valve bridge 32 or the one or more exhaust valves 22, for example, to maintain at least one of the exhaust valves 22 open during an engine braking event. In one aspect, a bushing 123 may be disposed within the first passage 112 and may receive the pintle 120. According to another configuration, the pin 120 may be arranged in the first passage without the bushing 123.According to the present illustrative example, the pintle 120 is disposed within the bushing 123 such that it can move axially relative to the housing 110 and the bushing 123. In one aspect, the pintle 120 can move axially between a first pintle position in which the pintle 120 is disengaged from the valve bridge 32 or from the one or more exhaust valves 22, and a second pintle position in which the pintle 120 is engaged with the valve bridge 32 or from the one or more exhaust valves 22. A return spring 124 can be disposed along the pintle 120 to bias the pintle 120 away from the valve bridge 32 and / or from the one or more exhaust valves 22.The return spring 124 may be desirable to maintain the pintle 120 in the first pintle position during normal engine operation and / or to return the pintle 120 to the first pintle position after an engine braking event.

[0029] Continue with Fig. 2, the engine braking system 100 may include a wedge 130 disposed within the second passage 113. The wedge 130 includes a first end 131 extending into the second passage 113 of the housing 110 and a second end 132 opposite the first end 131. Extending between the first end 131 and the second end 132 of the wedge 130 are both an upper surface 133 and a lower surface or actuation surface 134. The lower surface 134 may be concave or otherwise configured to engage or contact the first end 121 and actuate the pin 120 along the first axis 38. Additionally, the wedge 130 may include a chamfered area 135 between the first end 131 and the second end 132 that forms an angle α with the second axis 40. As discussed below, the angle α may be configured to allow the wedge 130 to be self-locking during an engine braking event.

[0030] According to one configuration, the wedge 130 can be Fig. 3 include a guide portion 136 configured to slide along the first lip 117a and the second lip 117b within the first channel 118a. As shown in Fig. 3, the lower surface 134 may be disposed laterally between the first lip 117a and the second lip 117b and extend from the guide portion 136 into the second channel 118b to contact the first end 121 of the pin 120.

[0031] According to another configuration, the wedge 130' can be Fig. 4 a cylindrical portion 139 disposed in the cylindrical opening 119 of the housing 110'.

[0032] In at least one aspect, the wedge 130, 130' may be configured to translate between a first wedge position and a second piston position along the second axis 40. When the pin 120 is adjacent to and / or contacting the wedge 130, 130' at the first end 131, the wedge 130, 130' is in the first wedge position. Upon actuation of the wedge 130, 130', as discussed in more detail below, the wedge 130, 130' may gradually move away from the first wedge position, with the pin 120 contacting the bottom surface 134 of the wedge 130, 130' between the first end 131 and the second end 132. As introduced above, the wedge 130, 130' may be configured to be self-locking.In other words, when the wedge 130, 130' leaves the first wedge position, the force of the valve spring 34 and the exhaust pressure from one or more cylinders of the engine 20 act on the wedge 130, 130' and maintain the axial position of the wedge 130, 130' such that the wedge 130, 130' is not retracted to the first wedge position during an engine braking event.

[0033] As in Fig. 2, Fig. 3 and Fig. As shown in Figure 4, the wedge 130, 130' may include a lost motion mechanism 137 comprising bolts or nuts. Alternatively, the lost motion mechanism 137 (e.g., slots) may be disposed on an angle bracket 141 that supports the solenoid 140 relative to the housing 110. The lost motion mechanism 137 may be adjusted during installation and / or service intervals to control the position of the wedge 130, 130' relative to an actuating mechanism, such as a solenoid 140.

[0034] Based on Fig.2, the solenoid 140 may be disposed on and / or coupled to the housing 110. The solenoid 140 includes an actuating arm 142 movable along the second axis 40. Additionally, the solenoid 140 may include a wedge return spring (not shown) contained within an armature cavity of the solenoid 140. The angle bracket 141 may, for example, be coupled to the housing 110 and to the solenoid 140 to axially align the actuating arm 142 with the second end 132 of the wedge 130.

[0035] In operation, during normal engine operation, the pintle 120 contacts the wedge 130 near the first end 131 and is axially spaced from the valve bridge 32 and / or the one or more exhaust valves 22. When engine braking is initiated (e.g., manually via the driver, automatically via a control module, etc.), the engine braking controller 36 may be configured to communicate with and / or provide instructions to the solenoid 140 to drive the wedge 130 axially along the second axis 40. The axial movement of the wedge 130 pushes the wedge 130 from the first wedge position toward the second wedge position, which simultaneously actuates the pintle 120 toward the valve bridge 32 and / or toward the one or more exhaust valves 22. In one aspect, the pin 120 may be driven by the wedge 130 while the valve bridge 32 is already being pushed downward by the rocker arm 24.In other words, no force is required to overcome the force of the valve spring 34 and / or the exhaust backpressure of a cylinder (not shown) of the engine 10. As the pintle 120 gradually reaches the second pintle position, it continuously inhibits the axial movement of the valve bridge 32 and / or the one or more exhaust valves 22, thus keeping the exhaust valve 22 open.

[0036] In another aspect, the timing of solenoid 140 does not need to be precise. Generally, the full opening (e.g., 1 mm) of exhaust valve 22 does not need to occur in one camshaft revolution of engine 10. Because wedge 130, 130' may be configured to be self-locking (i.e., not retract to the first wedge position until the engine braking event is complete), engine braking system 100 may be configured to allow additional movement of wedge 130, 130' and pintle 120 during subsequent crankshaft revolutions. When wedge 130, 130' leaves the first position, some degree of engine braking is still ensured. As wedge 130, 130' moves between the first wedge position and the second wedge position, and pintle 120 moves between the first pintle position and the second pintle position, a variable degree of engine braking may occur.Indeed, under certain conditions, an intermediate position of the wedge 130, 130' and the pin 120 between their respective first and second positions may be desired.

[0037] When the engine braking controller 36 deactivates or prevents engine braking, the solenoid 140 is de-energized and begins to pull the wedge 130 toward the first wedge position via the wedge return spring (not shown) contained within the armature cavity of the solenoid 140. As the wedge 130 returns to the first wedge position, the pintle 120 may simultaneously return to the first pintle position. The pintle return spring 124 may move the pintle 120 away from the valve bridge 32 and / or the one or more exhaust valves 22 such that no portion of the pintle 120 is in contact with the valve bridge 32 and / or the one or more exhaust valves 22.

Claims

[1] Engine braking system (100) comprising: a housing (110) comprising: a first passage (112) extending along a first axis (38), a second passage (113) extending along a second axis (40) intersecting the first axis (38), and wherein the first passage (112) communicates with the second passage (113); and a pin (120) disposed in the first passage (112) and configured to translate along the first axis (38) to keep one or more valves (22) of an internal combustion engine (10) open; characterized by , that the engine braking system (100) further comprises: a wedge (130) disposed in the second passage (113) and configured to slide along the second axis (40) and engage the pin (120); and a solenoid (140) coupled to the wedge (130) and configured to actuate the wedge (130) along the second axis (40). [2] The engine braking system (100) of claim 1, wherein the housing (110) further comprises a main body (111) defining the first passage (112) and the second passage (113), and a base (114) extending from the main body (111) and including one or more fastener holes (115). [3] The engine braking system (100) of claim 1, wherein the pin (120) is movable between a first pin position and a second pin position with respect to the first axis (38). [4] The engine braking system (100) of claim 3, wherein the pin (120) is disengaged from the one or more valves (22) of the internal combustion engine (10) in the first pin position, and wherein the pin (120) is engaged with the one or more valves (22) in the second pin position. [5] The engine braking system (100) of claim 4, further comprising a valve bridge (32) disposed between the pintle (120) and the one or more valves (22) of the internal combustion engine (10). [6] The engine braking system (100) of claim 4, wherein the wedge (130) is movable between a first wedge position and a second wedge position. [7] The engine braking system (100) of claim 6, wherein the engine braking system (100) is self-locking when the wedge (130) leaves the first wedge position and when the pin (120) leaves the first pin position. [8] The engine braking system (100) of claim 1, wherein the second passage (113) defines a cylindrical channel (119). [9] The engine braking system (100) of claim 8, wherein the wedge (130) further comprises a cylindrical body (139) having a first end (131) and a second end (132) opposite the first end (131). [10] The engine braking system (100) of claim 9, wherein the wedge (130) includes a chamfered portion (135) between the first end (131) and the second end (132) defining an actuating surface (134) configured to contact the pin (120).

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