An engine valve assembly including a stop mechanism that increases the force biasing the valve toward the closed position when the valve is at or near the closed position

Abstract

The present invention relates to an engine valve assembly including a stop mechanism that increases a force biasing a valve toward a closed position when the valve is at or near the closed position. A valve assembly includes a valve body defining an inner bore therein, a valve stem, a spring retainer, a valve spring, and a stop mechanism. The valve stem extends through the inner bore in the valve body and is adjustable between an open position and a closed position. The spring retainer is spaced apart from the valve body along a longitudinal axis of the valve stem and is fixed relative to the valve body. The spring retainer defines an inner bore through which the valve stem extends. The valve spring is captured between the valve body and the spring retainer and is configured to apply a biasing force to the valve stem that biases the valve stem toward the closed position. The stop mechanism is configured to increase the biasing force applied to the valve stem when the valve stem is at the closed position or within a predetermined distance of the closed position.

Description

[0001] INTRODUCTION

[0002] The information provided in this section is for the purpose of generally presenting the context of the disclosure. Aspects described in this section to the extent that they are not otherwise expressly recited in the claims are not to be necessarily construed as being prior art. TECHNICAL FIELD

[0003] The present disclosure relates to an engine valve assembly including a stop mechanism configured to increase a force biasing a valve toward its closed position when the valve is at or near its closed position. BACKGROUND

[0004] An intake or exhaust valve of an engine typically includes a valve body, a valve stem, a valve head, a valve guide, a valve spring, and a spring retainer. The valve body defines a bore through which intake or exhaust gas flows. The valve stem is a rod and the valve head is a disc attached to one end of the rod. The valve stem and head are collectively referred to as a poppet valve. The valve head seats against a valve seat defined by the valve body and plugs the bore therein to prevent gas flow through the bore when the poppet valve is in its closed position.

[0005] The valve guide maintains the valve stem and head structure in alignment with the valve seat. The valve spring biases the poppet valve toward its closed position. The spring retainer is spaced apart from the valve body along a longitudinal axis of the valve stem. The valve spring is captured between the valve body and the spring retainer. SUMMARY

[0006] A valve assembly for a cylinder of an engine is described herein. In one example, the valve assembly includes a valve body, a valve stem, a spring retainer, a valve spring, and a stop mechanism. The valve body defines an inner bore therein. The valve stem extends through the inner bore in the valve body. The valve stem is adjustable between an open position and a closed position. The spring retainer is spaced apart from the valve body along a longitudinal axis of the valve stem and is fixed relative to the valve body. The spring retainer defines an inner bore through which the valve stem extends. The valve spring is captured between the valve body and the spring retainer and is configured to apply a biasing force to the valve stem that biases the valve stem toward the closed position. The stop mechanism is configured to increase the biasing force applied to the valve stem when the valve stem is in the closed position or within a predetermined distance of the closed position.

[0007] In one aspect, the stop mechanism includes an annular groove formed on an outer radial surface of the valve stem and extending around a circumference of the outer radial surface, and a cup spring fixed relative to the valve body and disposed around the circumference of the valve stem radially outward of the annular groove in the valve stem.

[0008] In one aspect, the valve assembly further includes a ball stop captured between the valve stem and the cup spring. The ball stop engages the annular groove in the valve stem when the valve stem is in the closed position or within a predetermined distance of the closed position.

[0009] In one aspect, the valve assembly further includes a valve seal attached to an axial end surface of the valve body and engaging an outer radial surface of the valve stem. One end of the cup spring is attached to an outer radial surface of the valve seal, and the other end of the cup spring captures the ball stop.

[0010] In one aspect, the annular groove has a width that is greater than a diameter of the ball stop.

[0011] In one aspect, the annular groove has a sloped profile extending from a bottom surface of the annular groove to the outer radial surface of the valve stem. The ball stop engages the sloped profile as the valve stem moves from the closed position toward the open position.

[0012] In one aspect, the cup spring forms an annular rib that engages the annular groove in the valve stem when the valve stem is in the closed position or within a predetermined distance of the closed position.

[0013] In one aspect, the valve assembly further includes a valve seal attached to an axial end surface of the valve body and engaging an outer radial surface of the valve stem. One end of the cup spring is attached to an outer radial surface of the valve seal, and the other end of the cup spring forms an annular rib.

[0014] In one aspect, the cup spring includes a hollow cylindrical section attached to an outer radial surface of the valve seal and a hollow frustoconical section extending radially inward from the hollow cylindrical section to an annular rib formed by the cup spring. The annular rib projects radially inward from the hollow frustoconical section.

[0015] In one aspect, the stop mechanism includes an annular groove formed in an outer radial surface of the valve stem and extending around a circumference of the outer radial surface, a valve seal attached to the valve body and engaging the outer radial surface of the valve stem, and a pinch spring engaging an outer radial surface of the valve seal and extending around a circumference of the outer radial surface. The pinch spring biases the valve seal into engagement with the annular groove in the valve stem when the valve stem is in the closed position or within a predetermined distance of the closed position.

[0016] In one aspect, the valve seal includes a seal body and a seal lip. The seal body is attached to an axial end surface of the valve body and disposed around a circumference of the valve stem. The seal lip, which is attached to an inner radial surface of the seal body, projects radially inward therefrom and engages an outer radial surface of the valve stem. The pinch spring engages an outer radial surface of the seal lip.

[0017] In one aspect, the valve assembly further includes a valve guide having a hollow cylindrical body including a first portion disposed radially between the valve stem and the valve body and a second portion disposed radially between the valve seal and the valve stem.

[0018] In one aspect, the predetermined distance is less than 25% of a peak lift of the valve stem.

[0019] In another example, a valve assembly includes a valve body, a valve stem, a spring retainer, a valve spring, a cup spring, and at least one stop. The valve body defines an inner bore therein. The valve stem extends through the inner bore in the valve body and has an outer radial surface with an annular groove formed therein. The valve stem is adjustable between an open position and a closed position. The spring retainer is spaced apart from the valve body along a longitudinal axis of the valve stem and is fixed relative to the valve body. The spring retainer defines an inner bore through which the valve stem extends. The valve spring is captured between the valve body and the spring retainer and is configured to apply a biasing force to the valve stem that biases the valve stem toward the closed position. The cup spring is fixed relative to the valve body and disposed around a circumference of the valve stem radially outward of the annular groove in the valve stem. The at least one stop engages the annular groove in the valve stem when the valve stem is in the closed position and thereby prevents movement of the valve stem from the closed position toward the open position.

[0020] In one aspect, the at least one stop includes a ball stop captured between the valve stem and the cup spring.

[0021] In one aspect, the cup spring includes an annular segment that captures the ball stop.

[0022] In one aspect, the at least one stop includes an annular rib formed by the cup spring.

[0023] In one aspect, the annular groove has a sloped profile that extends from a bottom surface of the annular groove to the outer radial surface of the valve stem, and the at least one stop engages the sloped profile when the valve stem moves from the closed position toward the open position.

[0024] In another example, a valve assembly includes a valve body, a valve stem, a spring retainer, a valve spring, a valve seal, and a pinch spring. The valve body defines an inner bore therein. The valve stem extends through the inner bore in the valve body. The valve stem has an outer radial surface with an annular groove formed therein. The valve stem is adjustable between an open position and a closed position. The spring retainer is spaced apart from the valve body along a longitudinal axis of the valve stem and is fixed relative to the valve body. The spring retainer defines an inner bore through which the valve stem extends. The valve spring is captured between the valve body and the spring retainer and is configured to apply a biasing force to the valve stem that biases the valve stem toward the closed position. The valve seal is attached to the valve body and engages the outer radial surface of the valve stem. The pinch spring engages an outer radial surface of the valve seal and extends around a circumference thereof. The pinch spring biases the valve seal into engagement with the annular groove in the valve stem. The engagement between the valve seal and the annular groove prevents movement of the valve stem from the closed position toward the open position.

[0025] In one aspect, a valve seal includes a seal body and a seal lip. The seal body is attached to an axial end surface of a valve body and disposed about a circumference of a valve stem. The seal lip is attached to an inner radial surface of the seal body, projects radially inward therefrom, and engages an outer radial surface of the valve stem. A snap spring engages an outer radial surface of the seal lip.

[0026] The present invention provides the following technical solutions.

[0027] Technical Solution 1. A valve assembly for a cylinder of an engine, the valve assembly comprising:

[0028] a valve body defining an inner bore therein;

[0029] a valve stem extending through the inner bore in the valve body, wherein the valve stem is adjustable between an open position and a closed position;

[0030] a spring retainer spaced apart from and fixed relative to the valve body along a longitudinal axis of the valve stem, the spring retainer defining an inner bore through which the valve stem extends;

[0031] a valve spring captured between the valve body and the spring retainer and configured to apply a biasing force to the valve stem that biases the valve stem toward the closed position; and

[0032] a stop mechanism configured to increase the biasing force applied to the valve stem when the valve stem is in the closed position or within a predetermined distance of the closed position.

[0033] Technical Solution 2. The valve assembly of Technical Solution 1, wherein the stop mechanism comprises:

[0034] an annular groove formed in an outer radial surface of the valve stem and extending about a circumference of the outer radial surface; and

[0035] a cup-shaped spring fixed relative to the valve body and disposed about a circumference of the valve stem radially outward of the annular groove in the valve stem.

[0036] Technical Solution 3. The valve assembly of Technical Solution 2, further comprising a ball stop captured between the valve stem and the cup-shaped spring, wherein the ball stop engages the annular groove in the valve stem when the valve stem is in the closed position or within the predetermined distance of the closed position.

[0037] TECHNICAL SOLUTION 4. The valve assembly of TECHNICAL SOLUTION 3, further comprising a valve seal attached to an axial end surface of the valve body and engaging the outer radial surface of the valve stem, wherein one end of the cup spring is attached to an outer radial surface of the valve seal and the other end of the cup spring captures the ball stop.

[0038] TECHNICAL SOLUTION 5. The valve assembly of TECHNICAL SOLUTION 3, wherein a width of the annular groove is greater than a diameter of the ball stop.

[0039] TECHNICAL SOLUTION 6. The valve assembly of TECHNICAL SOLUTION 3, wherein the annular groove has a sloped profile extending from a bottom surface of the annular groove to the outer radial surface of the valve stem, the sloped profile being engaged by the ball stop as the valve stem moves from the closed position toward the open position.

[0040] TECHNICAL SOLUTION 7. The valve assembly of TECHNICAL SOLUTION 3, wherein the cup spring forms an annular rib that engages the annular groove in the valve stem when the valve stem is in the closed position or within the predetermined distance of the closed position.

[0041] TECHNICAL SOLUTION 8. The valve assembly of TECHNICAL SOLUTION 7, further comprising a valve seal attached to an axial end surface of the valve body and engaging the outer radial surface of the valve stem, wherein one end of the cup spring is attached to an outer radial surface of the valve seal and the other end of the cup spring forms the annular rib.

[0042] TECHNICAL SOLUTION 9. The valve assembly of TECHNICAL SOLUTION 8, wherein the cup spring comprises a hollow cylindrical section attached to the outer radial surface of the valve seal and a hollow frustoconical section extending radially inward from the hollow cylindrical section to the annular rib formed by the cup spring, the annular rib protruding radially inward from the hollow frustoconical section.

[0043] TECHNICAL SOLUTION 10. The valve assembly of TECHNICAL SOLUTION 1, wherein the stop mechanism comprises:

[0044] an annular groove formed in an outer radial surface of the valve stem and extending around a circumference of the outer radial surface;

[0045] a valve seal attached to the valve body and engaging the outer radial surface of the valve stem; and

[0046] a pinch spring engaging an outer radial surface of the valve seal and extending around a circumference of the outer radial surface, the pinch spring biasing the valve seal into engagement with the annular groove in the valve stem when the valve stem is in the closed position or within the predetermined distance of the closed position.

[0047] Technical Solution 11. The valve assembly of Technical Solution 10, wherein the valve seal comprises:

[0048] a seal body attached to an axial end surface of the valve body and disposed around a circumference of the valve stem; and

[0049] a seal lip attached to an inner radial surface of the seal body, projecting radially inward from the inner radial surface, and engaging the outer radial surface of the valve stem, wherein the pinch spring engages the outer radial surface of the seal lip.

[0050] Technical Solution 12. The valve assembly of Technical Solution 10, further comprising a valve guide having a hollow cylindrical body comprising a first portion disposed radially between the valve stem and the valve body and a second portion disposed radially between the valve seal and the valve stem.

[0051] Technical Solution 13. The valve assembly of Technical Solution 1, wherein the predetermined distance is less than 25% of a peak lift of the valve stem.

[0052] Technical Solution 14. A valve assembly for a cylinder of an engine, the valve assembly comprising:

[0053] a valve body defining an inner bore therein;

[0054] a valve stem extending through the inner bore in the valve body, the valve stem having an outer radial surface with an annular groove formed therein, wherein the valve stem is adjustable between an open position and a closed position;

[0055] a spring retainer spaced apart from and fixed relative to the valve body along a longitudinal axis of the valve stem, the spring retainer defining an inner bore through which the valve stem extends;

[0056] a valve spring captured between the valve body and the spring retainer and configured to apply a biasing force to the valve stem biasing the valve stem toward the closed position;

[0057] a cup spring fixed relative to the valve body and disposed around a circumference of the valve stem radially outward of the annular groove in the valve stem; and

[0058] at least one stop that engages the annular groove in the valve stem when the valve stem is in the closed position and thereby prevents movement of the valve stem from the closed position toward the open position.

[0059] Technical Solution 15. The valve assembly of Technical Solution 14, wherein the at least one stop comprises a ball stop captured between the valve stem and the cup spring.

[0060] Technical Solution 16. The valve assembly of Technical Solution 15, wherein the cup spring comprises an annular section that captures the ball stop.

[0061] Technical Solution 17. The valve assembly of Technical Solution 14, wherein the at least one stop comprises an annular rib formed by the cup spring.

[0062] Technical Solution 18. The valve assembly of Technical Solution 14, wherein the annular groove has a sloped profile extending from a bottom surface of the annular groove to the outer radial surface of the valve stem, the at least one stop engaging the sloped profile when the valve stem moves from the closed position toward the open position.

[0063] Technical Solution 19. A valve assembly for a cylinder of an engine, the valve assembly comprising:

[0064] a valve body defining an inner bore therein;

[0065] a valve stem extending through the inner bore in the valve body, the valve stem having an outer radial surface with an annular groove formed therein, wherein the valve stem is adjustable between an open position and a closed position;

[0066] a spring retainer spaced apart from and fixed relative to the valve body along a longitudinal axis of the valve stem, the spring retainer defining an inner bore through which the valve stem extends;

[0067] a valve spring captured between the valve body and the spring retainer and configured to apply a biasing force to the valve stem that biases the valve stem toward the closed position;

[0068] a valve seal attached to the valve body and engaging the outer radial surface of the valve stem; and

[0069] a pinch spring engaging an outer radial surface of the valve seal and extending around a circumference of the outer radial surface, the pinch spring biasing the valve seal into engagement with the annular groove in the valve stem, the engagement between the valve seal and the annular groove preventing movement of the valve stem from the closed position toward the open position.

[0070] Technical Solution 20. The valve assembly of Technical Solution 19, wherein the valve seal comprises:

[0071] a seal body attached to an axial end surface of the valve body and disposed around a circumference of the valve stem; and

[0072] a seal lip attached to an inner radial surface of the seal body, projecting radially inward from the inner radial surface, and engaging the outer radial surface of the valve stem, wherein the pinch spring engages the outer radial surface of the seal lip.

[0073] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0074] The present disclosure will become more fully understood from the detailed description, the claims and the drawings. Whereby:

[0075] Figure 1 is a cross-sectional view of a valve assembly including an example of a valve stem shown in its closed position, a valve spring, and a stop mechanism according to the present disclosure;

[0076] Figure 2 is a cross-sectional view of the valve assembly of Figure 1 , wherein the valve stem is shown in its open position;

[0077] Figure 3 is a cross-sectional view of a variant of the valve assembly of Figure 1 , wherein the valve stem defines an annular groove having a sloped profile;

[0078] Figure 4 is a graph illustrating the biasing force exerted by the valve spring and the stop mechanism that urges the valve stem toward its closed position;

[0079] Figure 5 is a cross-sectional view of a valve assembly including another example of a valve stem shown in its closed position and a stop mechanism according to the present disclosure;

[0080] Figure 6 is a cross-sectional view of the valve assembly of Figure 5 , wherein the valve stem is shown in its open position;

[0081] Figure 7 is a cross-sectional view of a valve assembly including a valve stem shown in its closed position and a stop mechanism according to the present disclosure; and

[0082] Figure 8 is a cross-sectional view of a valve assembly of Figure 7 is a cross-sectional view of a valve assembly of

[0083] In the drawings, reference numerals can be repeated among the figures for like and / or identical elements. DETAILED DESCRIPTION

[0084] During compression-release engine braking, the exhaust valve of a cylinder opens just before the end of the compression stroke of the cylinder, which releases the compressed gas trapped in the cylinder and thus slows the vehicle. This process generates high exhaust pressure, which can cause the exhaust valve to open independent of the valve actuator that controls the position of the exhaust valve. Engine braking by restricting exhaust flow and / or increasing boost pressure can also generate high exhaust pressure and thus can also cause the exhaust valve to open independent of its valve actuator. If the biasing force of the valve spring is less than the difference between the force of the exhaust gas acting on the backside of the poppet valve and the force of the compressed gas acting on the cylinder side of the poppet valve, the poppet valve can open independent of its valve actuator. While this problem can be solved by increasing the spring rate of the valve spring, increasing the spring rate of the valve spring decreases engine efficiency.

[0085] A valve assembly according to the present disclosure includes a stop mechanism that solves the above problem without decreasing engine efficiency. The stop mechanism only increases the biasing force that urges the poppet valve toward its closed position when the poppet valve is at or near its closed position, which prevents the poppet valve from opening independent of its valve actuator even when the engine is operating at high load and high speed. Conversely, the stop mechanism does not affect the force applied by the valve actuator to open the poppet valve when the poppet valve is away from its closed position.

[0086] In one example, the stop mechanism includes an annular groove in the valve stem, a ball stop, and a cup spring that biases the ball stop into engagement with the annular groove when the poppet valve is at or near its closed position. In another example, the stop mechanism includes an annular groove in the valve stem and a cup spring, and one end of the cup spring forms an annular rib that engages the annular groove when the poppet valve is at or near its closed position. In yet another example, the stop mechanism includes an annular groove in the valve stem, a valve seal, and a pinch spring that compresses the valve seal into the annular groove when the poppet valve is at or near its closed position.

[0087] Reference is now made to Figure 1 and Figure 2Valve assembly 10 can be an intake valve or an exhaust valve of an engine. Valve assembly 10 includes a valve body 12, a valve stem 14, a valve guide 16, a valve seal 18, a valve spring 20, a spring retainer 22, and a stop mechanism 24. Valve body 12 defines an inner bore 25 through which valve stem 14 extends. Valve body 12 can be part of an engine cylinder head. The cylinder head can be placed on top of an engine block (not shown) that defines the cylinders of the engine. Valve body 12 can be made of aluminum.

[0088] Valve stem 14 can be in the closed position ( Figure 1 ) and opening position ( Figure 2 Adjustment is made between [variable names]. The valve stem 14 has a cylindrical body with an upper end 26, a lower end (not shown) opposite to the upper end 26, and an outer radial surface 28. A valve head (not shown) is connected to the lower end of the valve stem 14. The valve head may be disc-shaped. When the valve stem 14 is in its [position], [the valve head is adjusted accordingly]. Figure 1 In the closed position shown, the valve head is positioned against the valve seat defined by the cylinder head to prevent gas from flowing into or out of one of the cylinders. When the valve stem 14 is in its closed position... Figure 2 In the open position shown, the valve head is positioned against the valve seat defined by the cylinder head to prevent gas from flowing into or out of the cylinder.

[0089] The outer radial surface 28 of the valve stem 14 has a first annular groove 30 and a second annular groove 32 formed therein and extending around its circumference. The first annular groove 30 in the valve stem 14 receives a portion of the spring retainer 22. The engagement between the spring retainer 22 and the first annular groove 30 in the valve stem 14 secures the spring retainer 22 to the valve stem 14. The second annular groove 32 in the valve stem 14 receives a portion of the stop mechanism 24.

[0090] When the valve stem 14 is actuated between its open and closed positions, it translates via the valve guide 16. The valve guide 16 keeps the valve stem 14 aligned with the inner bore 25 in the valve body 12. Furthermore, when the valve stem 14 is actuated between its open and closed positions, the valve guide 16 acts as a bushing by minimizing wear on the valve body 12 and the valve stem 14. The valve stem 14 and the valve guide 16 may be made of steel.

[0091] The valve guide 16 has a hollow cylindrical body with a first portion 34 and a second portion 36. The first portion 34 of the valve guide 16 is disposed in an inner bore 25 in the valve body 12 and is radially positioned between the valve stem 14 and the valve body 12. The second portion 36 of the valve guide 16 is disposed outside the inner bore 25 in the valve body 12 and is radially positioned between the valve seal 18 and the valve stem 14. The valve guide 16 can be pressed into the inner bore 25 in the valve body 12.

[0092] Valve seal 18 seals the interface between valve body 12 and valve stem 14. Valve seal 18 includes a seal body 38, a seal lip 40, and a grip spring 41. Seal body 38 is attached (e.g., welded) to an axial end surface 42 of valve body 12 and is disposed about the circumference of valve stem 14. Seal body 38 is made of a rigid material, such as steel. Seal lip 40 is attached to an inner radial surface 44 of seal body 38 and projects radially inward from inner radial surface 44. Seal lip 40 is made of a flexible material, such as rubber, and can be overmolded to seal body 38. Grip spring 41 biases seal lip 40 into engagement with outer radial surface 28 of valve stem 14.

[0093] Valve spring 20 applies a biasing force to valve stem 14 that biases valve stem 14 toward its closed position. Valve spring 20 is captured between valve body 12 (or valve seal 18) and spring retainer 22. Valve spring 20 is a coil spring made of a metal, such as steel.

[0094] Spring retainer 22 retains valve spring 20. Spring retainer 22 is spaced apart from valve body 12 along a longitudinal axis 46 of valve stem 14 and is fixed relative to valve body 12. Spring retainer 22 defines an inner bore 48 through which valve stem 14 extends.

[0095] Spring retainer 22 includes a retainer body 50 and a retainer 52. Retainer body 50 is made of a rigid material, such as steel. Retainer 52 is made of a flexible material, such as rubber, and can be overmolded to retainer body 50. Retainer 52 can have a cylindrical shape in its relaxed state. When spring retainer 22 is assembled to valve stem 14, retainer 52 is compressed between retainer body 50 and valve stem 14. In turn, retainer 52 includes an annular protrusion 54 that engages first annular groove 30 in valve stem 14 and thereby secures spring retainer 22 to valve stem 14.

[0096] Stop mechanism 24 increases the biasing force that urges valve stem 14 toward its closed position when valve stem 14 is in its closed position or within a predetermined distance of its closed position. In one example, the predetermined distance is less than 25% of the peak lift of valve stem 14 (and the valve head coupled thereto). In another example, the predetermined distance is less than 2 millimeters (mm). Stop mechanism 24 includes second annular groove 32 in valve stem 14, a cup spring 56, and a ball stop 58.

[0097] The cup spring 56 is fixed relative to the valve body 12 and is disposed around the circumference of the valve stem 14 radially outward of the second annular groove 32 in the valve stem 14. The cup spring 56 has a first end 60 and a second end 62 opposite the first end 60. The first end 60 of the cup spring 56 is attached to an outer radial surface 64 of the valve seal 18. The second end 62 of the cup spring 56 captures the ball detent 58 and applies a biasing force to the ball detent 58 that urges the ball detent 58 into engagement with the second annular groove 32 in the valve stem 14. The cup spring 56 can be made of a metal such as steel.

[0098] The cup spring 56 includes a hollow cylindrical section 66, a hollow frustoconical section 68, and an annular section 70. The hollow cylindrical section 66 extends from the first end 60 of the cup spring 56 to the hollow frustoconical section 68 along the longitudinal axis 46 of the valve stem 14. The hollow frustoconical section 68 extends from the hollow cylindrical section 66 to the annular section 70 along the longitudinal axis 46 of the valve stem 14. The annular section 70 extends from the hollow cylindrical section 66 to the second end 62 of the cup spring 56 along the longitudinal axis 46 of the valve stem 14. The annular section 70 captures the ball detent 58.

[0099] When the valve stem 14 is in its closed position, the ball detent 58 engages the second annular groove 32 in the valve stem 14 and thus prevents movement of the valve stem 14 from its closed position toward its open position. Although only two ball detents 58 are shown, the detent mechanism 24 can include more than two ball detents 58 and the ball detents 58 can be disposed around the entire circumference of the valve stem 14. Each ball detent 58 has a spherical shape and can be made of a metal such as steel.

[0100] A valve actuator (not shown) moves the valve stem 14 in a downward direction 72 to adjust the valve stem 14 from its closed position ( Figure 1 ) to its open position ( Figure 2 ). In doing so, the valve actuator compresses the valve spring 20 and thus overcomes the biasing force applied by the valve spring 20 that urges the valve stem 14 toward its closed position. In addition, the valve actuator moves the ball detent 58 radially outward out of the second annular groove 32 in the valve stem 14 and thus overcomes the biasing force applied by the cup spring 56 that urges the ball detent 58 into engagement with the second annular groove 32.

[0101] Once the ball stop 58 has disengaged from the second annular groove 32 in the valve stem 14, the stop mechanism 24 will not increase the biasing force pushing the valve stem 14 toward its closed position. Therefore, the stop mechanism 24 only increases the biasing force pushing the valve stem 14 toward its closed position when the valve stem 14 is in its closed position or within a predetermined distance of the closed position. The predetermined distance can be equal to the amount of time the valve stem 14 travels between its closed position and the position where the ball stop 58 is initially removed from the second annular groove 32 in the valve stem 14.

[0102] exist Figure 1 and Figure 2 In the example shown, the radius of the second annular groove 32 in the valve stem 14 is equal to or nearly equal to the radius of each ball stop 58. Therefore, due to manufacturing tolerances, the ball stops 58 may not engage the second annular groove 32 in the valve stem 14 when the valve stem 14 is in its closed position. Figure 3 In the example shown, the second annular groove 32 in the valve stem 14 has a radius different from that of each ball stop 58. More specifically, the second annular groove 32 in the valve stem 14 has a width W greater than the diameter D of each ball stop 58 to absorb manufacturing tolerances.

[0103] Furthermore, the second annular groove 32 in the valve stem 14 has an inclined profile 74 extending from the bottom surface 76 of the second annular groove 32 to the outer radial surface 28 of the valve stem 14. When the valve stem 14 moves from its closed position toward its open position, the ball stop 58 engages the inclined profile 74. Additionally, the second annular groove 32 in the valve stem 14 has an inclined profile 78 that extends from the bottom surface 76 of the second annular groove 32 to the outer radial surface 28 of the valve stem 14 in a direction opposite to the inclined profile 74.

[0104] At least a portion of the inclined profile 74 of the second annular groove 32 in the valve stem 14 is oriented at a first angle A1 relative to the outer radial surface 28 of the valve stem 14. Increasing the first angle A1 of the inclined profile 74 results in the stop mechanism 24 applying a larger biasing force to push the valve stem 14 toward its closed position, while providing a lower ability to accommodate manufacturing tolerances. Decreasing the first angle A1 of the inclined profile 74 has the opposite effect. In one example, the first angle A1 of the inclined profile 74 is in the range of 35 degrees and 55 degrees (e.g., 45 degrees).

[0105] At least a portion of the sloped profile 78 of the second annular groove 32 in the valve stem 14 is oriented at a second angle A2 relative to the outer radial surface 28 of the valve stem 14. As a result, the force required to move the ball stop 58 out of the second annular groove 32 in the downward direction 72 is greater than the force required to move the ball stop 58 out of the second annular groove 32 in the opposite upward direction. This prevents the ball stop 58 from moving in the downward direction 72 past the second annular groove 32 in the valve stem 14 and damaging the valve seal 18.

[0106] The sloped profiles 74, 78 of the second annular groove 32 in the valve stem 14 and the bottom surface 76 of the second annular groove 32 form the entire profile of the second annular groove 32. None of the sections of the profile of the second annular groove 32 are parallel to the longitudinal axis 46 of the valve stem 14. As a result, the bottom surface 76 of the second annular groove 32 is not flat. As a result, the stop mechanism 24 increases the biasing force that pushes the valve stem 14 toward its closed position throughout the entire engagement between the ball stop 58 and the second annular groove 32 in the valve stem 14.

[0107] Reference is now made to Figure 4 The graph 80 illustrates example biasing forces 82, 84 that push the valve stem 14 toward its closed position. The biasing force 82 represents the biasing force applied by the valve spring 20 alone. The biasing force 84 represents the biasing force applied by the valve spring 20 and the stop mechanism 24. The biasing forces 82, 84 are plotted relative to an x-axis 86 and a y-axis 88, the x-axis 86 representing valve lift in mm, and the y-axis 88 representing force in Newtons (N).

[0108] At a valve lift of 0 mm, the biasing force 82 is approximately 380 N, and the biasing force 84 is approximately 410 N. As a result, the stop mechanism 24 increases the biasing force that pushes the valve stem 14 toward its closed position by approximately 30 N. The stop mechanism 24 continues to increase this biasing force by approximately 30 N as the valve stem 14 moves from its closed position toward its open position until the valve lift is approximately 1.5 mm. At this point, the stop mechanism 24 stops increasing the biasing force that pushes the valve stem 14 toward its closed position, and the biasing forces 82, 84 are equal to each other.

[0109] Reference is now made to Figure 5 and Figure 6The diagram illustrates a valve assembly 10 having a stop mechanism 90 that replaces the stop mechanism 24. The stop mechanism 90 includes a second annular groove 32 in the valve stem 14 and a cup spring 92. The cup spring 92 has a first end 94 and a second end 96 opposite to the first end 94. The first end 94 of the cup spring 92 is attached to the outer radial surface 28 of the valve seal 18. Like the cup spring 56, the cup spring 92 includes a hollow cylindrical section 66 and a hollow frustum-shaped conical section 68. Unlike the stop mechanism 24, the stop mechanism 90 does not include a ball stop 58, and the cup spring 92 does not include an annular section 70 that captures the ball stop 58. Instead, the second end 96 of the cup spring 92 forms an annular rib 98 that engages the outer radial surface 28 of the valve stem 14.

[0110] When the valve stem 14 is in its closed position or within a predetermined distance of the closed position, the hollow frustum-shaped section 68 of the cup spring 92 biases the annular rib 98 to engage with the second annular groove 32 in the valve stem 14. The engagement between the annular rib 98 and the second annular groove 32 prevents movement of the valve stem 14 from its closed position toward its open position. The cup spring 92 may be made of a metal such as steel. Figure 5 and Figure 6 In the example shown, the second annular groove 32 in the valve stem 14 has a hemispherical profile with a radius approximately equal to the radius of the annular rib 98. In other examples, the second annular groove 32 in the valve stem 14 may have, for example... Figure 3 The example shows an inclined profile, and the width W of the second annular groove 32 can be greater than the height H1 of the annular rib 98.

[0111] Now for reference Figure 7 and Figure 8 The diagram shows a valve assembly 10 having a stop mechanism 100 instead of a stop mechanism 24. The stop mechanism 100 includes a second annular groove 32 in the valve stem 14, an upper portion 102 of a sealing lip 104, and a locking spring 106. Like the sealing lip 40, the sealing lip 104 is attached to and extends radially inward from the inner radial surface 44 of the sealing body 38. The sealing lip 104 is made of a flexible material such as rubber and can be overmolded onto the sealing body 38. In contrast to the sealing lip 40, the sealing lip 104 includes an upper portion 102 that extends upward from the portion of the sealing lip 104 corresponding to the sealing lip 40.

[0112] The snap spring 106 engages the outer radial surface 108 of the seal lip 104 and extends around the circumference of the outer radial surface 108. When the valve stem 14 is in its closed portion or within a predetermined distance of the closed portion, the snap spring 106 biases the seal lip 104 into engagement with the second annular groove 32 in the valve stem 14. The snap spring 106 can be made of steel. In various implementations, the snap springs 41, 106 can be replaced with a single snap spring.

[0113] The upper portion 102 of the seal lip 104 can have a cylindrical shape in its relaxed state. When the snap spring 106 engages the outer radial surface 108 of the seal lip 104, the snap spring 106 compresses the seal lip 104 radially inward and thus forms an annular protrusion 110 in the upper portion 102 of the seal lip 104. The annular protrusion 110 on the seal lip 104 protrudes radially inward from the rest of the upper portion 102 of the seal lip 104. When the valve stem 14 is in its closed position, the annular protrusion 110 on the seal lip 104 engages the second annular groove 32 in the valve stem 14 and thus prevents movement of the valve stem 14 from its closed position toward its open position. In Figure 7 and Figure 8 In the example shown in Figs. 1-3, the second annular groove 32 in the valve stem 14 has a hemispherical profile with a radius approximately equal to the radius of the annular protrusion 110. In other examples, the second annular groove 32 in the valve stem 14 can have a sloped profile as shown in the example of Figs. 4-5, and the width W of the second annular groove 32 can be greater than the height H2 of the annular protrusion 110. Figure 3

[0114] The previous description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, specification, and claims. It should be understood that one or more steps within a method can be executed in different order (or concurrently) without altering the principles of the disclosure. Also, although each of the embodiments describes particular combinations of features, any one or more features from any of the embodiments can be used in combination, or any one or more features from any of the embodiments can be used alone, with or without the presence of other features described in the foregoing examples, even though not explicitly stated in the examples. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments' features with respect to each other remain within the scope of the disclosure.

[0115] ​Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed." Unless explicitly described as being "direct," a relationship between a first and a second element described in the above disclosure can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements (spatially or functionally) are present between the first and second elements.

[0116] To facilitate description, spatially relative terms, such as "internal," "external," "lower," "bottom," "bottom portion," "upper," "top," and the like, can be used herein to describe one element's or feature's relationship to another element or feature as illustrated in the figures. Spatially relative terms can be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0117] Although the terms first, second, third, and the like can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can be only used to distinguish one element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numeric terms, as used herein, do not imply a sequence or order to the items described. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0118] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, the phrase "at least one of A, B, and C" should be construed to mean a logical (A or B or C), using the non- exclusive logical OR, and should not be construed to mean "at least one of (A and B) or (A and C)," an exclusive disjunction logical expression.

Claims

1. A valve assembly for a cylinder of an engine, the valve assembly comprising: a valve body defining an inner bore therein; a valve stem extending through the inner bore in the valve body, wherein the valve stem is adjustable between an open position and a closed position; a spring retainer spaced apart from and fixed relative to the valve body along a longitudinal axis of the valve stem, the spring retainer defining an inner bore through which the valve stem extends; a valve spring captured between the valve body and the spring retainer and configured to apply a biasing force to the valve stem, the biasing force biasing the valve stem toward the closed position; and a stop mechanism configured to increase the biasing force applied to the valve stem when the valve stem is in the closed position or within a predetermined distance of the closed position.

2. The valve assembly of claim 1, wherein, the stop mechanism comprising: an annular groove formed in an outer radial surface of the valve stem and extending around a circumference of the outer radial surface; and a cup spring fixed relative to the valve body and disposed around a circumference of the valve stem radially outward of the annular groove in the valve stem.

3. The valve assembly of claim 2, further comprising a ball stop captured between the valve stem and the cup spring, wherein, the ball stop engages the annular groove in the valve stem when the valve stem is in the closed position or within the predetermined distance of the closed position.

4. The valve assembly of claim 3, further comprising a valve seal attached to an axial end surface of the valve body and engaging the outer radial surface of the valve stem, wherein, one end of the cup spring is attached to an outer radial surface of the valve seal and the other end of the cup spring captures the ball stop.

5. The valve assembly of claim 3, wherein, a width of the annular groove is greater than a diameter of the ball stop.

6. The valve assembly of claim 3, wherein, the annular groove has a sloped profile extending from a bottom surface of the annular groove to the outer radial surface of the valve stem, the sloped profile engaged by the ball stop when the valve stem moves from the closed position toward the open position.

7. The valve assembly of claim 3, wherein, the cup spring forms an annular rib that engages the annular groove in the valve stem when the valve stem is in the closed position or within the predetermined distance of the closed position.

8. The valve assembly of claim 7, further comprising a valve seal attached to an axial end surface of the valve body and engaging the outer radial surface of the valve stem, wherein, one end of the cup spring is attached to an outer radial surface of the valve seal and the other end of the cup spring forms the annular rib.

9. The valve assembly of claim 8, wherein, the cup spring includes a hollow cylindrical section attached to the outer radial surface of the valve seal and a hollow frustoconical section extending radially inward from the hollow cylindrical section to the annular rib formed by the cup spring, the annular rib projecting radially inward from the hollow frustoconical section.

10. The valve assembly of claim 1, wherein, the stop mechanism comprising: an annular groove formed in an outer radial surface of the valve stem and extending around a circumference of the outer radial surface; a valve seal attached to the valve body and engaging the outer radial surface of the valve stem; and a pinch spring engaging an outer radial surface of the valve seal and extending around a circumference of the outer radial surface, the pinch spring biasing the valve seal into engagement with the annular groove in the valve stem when the valve stem is in the closed position or within the predetermined distance of the closed position.

11. The valve assembly of claim 10, wherein, the valve seal comprising: a seal body attached to an axial end surface of the valve body and disposed around a circumference of the valve stem; and a a sealing lip attached to an inner radial surface of the seal body, extending radially inwardly from the inner radial surface, and engaging the outer radial surface of the valve stem, wherein the clamp spring engages the outer radial surface of the sealing lip.

12. The valve assembly of claim 10, further comprising a valve guide having a hollow cylindrical body including a first portion disposed radially between the valve stem and the valve body and a second portion disposed radially between the valve seal and the valve stem.

13. The valve assembly of claim 1, wherein, the predetermined distance is less than 25% of a peak lift of the valve stem.

14. A valve assembly for a cylinder of an engine, the valve assembly comprising: a valve body defining an inner bore therein; a valve stem extending through the inner bore in the valve body, the valve stem having an outer radial surface with an annular groove formed therein, wherein the valve stem is adjustable between an open position and a closed position; a spring retainer spaced apart from and fixed relative to the valve body along a longitudinal axis of the valve stem, the spring retainer defining an inner bore through which the valve stem extends; a valve spring captured between the valve body and the spring retainer and configured to apply a biasing force to the valve stem biasing the valve stem toward the closed position; a cup spring fixed relative to the valve body and disposed about a circumference of the valve stem radially outward of the annular groove in the valve stem; and at least one stop engaging the annular groove in the valve stem when the valve stem is in the closed position and thereby preventing movement of the valve stem from the closed position toward the open position.

15. The valve assembly of claim 14, wherein, the at least one stop comprises a ball stop captured between the valve stem and the cup spring.

16. The valve assembly of claim 15, wherein, the cup spring comprises an annular segment that captures the ball stop.

17. The valve assembly of claim 14, wherein, the at least one stop comprises an annular rib formed by the cup spring.

18. The valve assembly of claim 14, wherein, the annular groove has a sloped profile extending from a bottom surface of the annular groove to the outer radial surface of the valve stem, the sloped profile being engaged by the at least one stop when the valve stem is moved from the closed position toward the open position.

19. A valve assembly for a cylinder of an engine, the valve assembly comprising: a valve body defining an inner bore therein; a valve stem extending through the inner bore in the valve body, the valve stem having an outer radial surface with an annular groove formed therein, wherein the valve stem is adjustable between an open position and a closed position; a spring retainer spaced apart from and fixed relative to the valve body along a longitudinal axis of the valve stem, the spring retainer defining an inner bore through which the valve stem extends; a valve spring captured between the valve body and the spring retainer and configured to apply a biasing force to the valve stem biasing the valve stem toward the closed position; a valve seal attached to the valve body and engaging the outer radial surface of the valve stem; and a sealing lip attached to an inner radial surface of the seal body, extending radially inwardly from the inner radial surface, and engaging the outer radial surface of the valve stem, wherein the clamp spring engages the outer radial surface of the sealing lip. A pinch spring engaging an outer radial surface of the valve seal and extending around a circumference of the outer radial surface, the pinch spring biasing the valve seal into engagement with the annular groove in the valve stem, the engagement between the valve seal and the annular groove preventing movement of the valve stem from the closed position toward the open position.

20. The valve assembly of claim 19, wherein, The valve seal includes: a seal body attached to an axial end surface of the valve body and disposed around a circumference of the valve stem; and a seal lip attached to an inner radial surface of the seal body, projecting radially inward from the inner radial surface, and engaging the outer radial surface of the valve stem, wherein the pinch spring engages the outer radial surface of the seal lip.

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