Switchable rocker arm
By introducing a locking and stop mechanism into the switchable rocker arm, the friction problem between the outer arm and the camshaft is solved, simplifying the design and reducing the performance requirements of the anti-disengagement spring, resulting in less wear and higher efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SCHAEFFLER HLDGCHINA
- Filing Date
- 2020-12-29
- Publication Date
- 2026-06-12
AI Technical Summary
Existing switchable rocker arms have unnecessary friction between the outer arm and the outer cam of the camshaft in low lift mode, and the anti-disengagement spring design is difficult, especially when the lift difference is large and the performance requirements are high.
A switchable rocker arm is designed, comprising first and second split arms, a locking mechanism, a stop mechanism, and an anti-disengagement spring. In the unlocked state, the second split arm disengages from the cam profile, reducing friction, and the stop mechanism maintains the position of the split arm in the unlocked state, reducing the performance requirements of the anti-disengagement spring.
This reduces friction between the second valve arm and the cam, lowers wear, simplifies the design, reduces the performance requirements of the anti-disengagement spring, and improves the overall efficiency and reliability of the variable valve mechanism.
Smart Images
Figure CN112796847B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of vehicle technology. Specifically, it relates to a switchable rocker arm for a variable valve mechanism in an internal combustion engine. Background Technology
[0002] Variable valve timing mechanisms are commonly used to improve internal combustion engine performance, enhance fuel economy, and reduce emissions. One known feasible solution is a switchable rocker arm.
[0003] For example, Chinese patent application CN 110023594 A discloses a variable valve mechanism for a piston internal combustion engine. In this design, the switchable rocker arm has two arms, an inner arm and an outer arm. The switchable rocker arm can be switched between a locked state and an unlocked state by means of a locking mechanism. In different states, the switchable rocker arm contacts different cam lobe angles of the camshaft via different arms, thereby transmitting different lift to the valve stems of the associated intake or exhaust valves.
[0004] In a switchable rocker arm operating scheme, the inner cam of the camshaft engages with the inner arm of the switchable rocker arm to achieve a low-lift mode; while the outer cam of the camshaft engages with the outer arm of the switchable rocker arm to achieve a high-lift mode. To prevent the outer arm from disengaging from the outer cam of the camshaft, an anti-disengagement spring is also provided in the switchable rocker arm. However, in the low-lift mode, the outer arm of the switchable rocker arm idles. Therefore, in the low-lift mode, unnecessary friction always exists between the outer arm of the switchable rocker arm and the outer cam of the camshaft, thereby accelerating the wear of the outer arm and the outer cam. Furthermore, when the difference between the low and high lift is large, the performance requirements for the anti-disengagement spring, which is arranged within a limited space, are very high, making the design of the anti-disengagement spring extremely difficult. Summary of the Invention
[0005] Therefore, the object of the present invention is to provide a switchable rocker arm for a variable valve mechanism, which experiences less wear relative to the cam during operation.
[0006] The aforementioned objective is achieved by a switchable rocker arm. The switchable rocker arm is used in a variable valve timing mechanism to provide different valve lifts in conjunction with a cam. The switchable rocker arm includes a first and a second split arm movable relative to each other, and a locking mechanism for locking and unlocking the first and second split arms. In the unlocked state, the first split arm contacts a first profile of the mating cam to provide a first valve lift; and in the locked state, the second split arm contacts a second profile of the mating cam to provide a second valve lift different from the first valve lift. The switchable rocker arm also includes a stop mechanism, wherein in the unlocked state, the second split arm can be stopped by the stop mechanism at a stop position relative to the first split arm, at which point the second split arm disengages from the second profile of the cam.
[0007] Within the scope of this document, a switchable rocker arm is used in a variable valve timing mechanism to engage with a cam. Here, the cam specifically refers to a cam member with a predetermined profile constructed at the camshaft. As the camshaft rotates, the switchable rocker arm oscillates under the influence of the cam member, thereby adjusting the valve travel. Preferably, the switchable rocker arm can be constructed as a roller rocker arm. Alternatively, other types of rocker arms can also be constructed.
[0008] Here, the switchable rocker arm has at least two arms, namely a first arm and a second arm. The two arms of the switchable rocker arm can move relative to each other, for example, pivot relative to each other. It should be noted that this document does not limit the relative movement connection between the arms of the switchable rocker arm.
[0009] Here, the switchable rocker arm has a locking mechanism. The two arms of the switchable rocker arm can achieve different relative positions using the locking mechanism. In the unlocked state, the switchable rocker arm abuts against the first profile of the camshaft with its first arm, so that when the camshaft rotates, the switchable rocker arm can cooperate with the cam member to provide a first valve lift. In the locked state, the switchable rocker arm abuts against the second profile of the camshaft with its second arm, so that when the camshaft rotates, the switchable rocker arm can cooperate with the cam member to provide a second valve lift different from the first valve lift. Optionally, the first and second profiles can be constructed on the same cam member, such as a cam plate. In this case, the first and second arms abut against different parts of the cam member. Alternatively, the first and second profiles can be constructed on different cam members, such as cam plates. In this case, the first and second arms abut against cam members arranged adjacent to each other on the same camshaft.
[0010] Here, the switchable rocker arm has a stop mechanism. In the unlocked state of the switchable rocker arm, the second arm can be stopped at a stop position relative to the first arm by means of the stop mechanism, and the second arm does not contact the second profile of the cam at the stop position. In this case, the stop position can be understood as: the relative position range of the second arm relative to the first arm. When the second arm is within this relative position range, in the switchable rocker arm, the first arm is in contact with the first profile of the cam member, while the second arm is disengaged or does not contact the second profile of the cam member. Therefore, the stop mechanism allows the second arm to remain separated from the cam member.
[0011] Here, the switchable rocker arm preferably also has an anti-disengagement spring. Advantageously, the anti-disengagement spring is tensioned between the first and second split arms. In the unlocked state of the switchable rocker arm, the second split arm can re-engage with the second profile of the cam after the stop is released, thanks to the anti-disengagement spring. Optionally, the anti-disengagement spring is constructed as a helical compression spring. Optionally, the anti-disengagement spring is constructed as a torsion spring.
[0012] Since the second valve stem does not contact the camshaft assembly, especially the second profile, when the switchable rocker arm is in the unlocked state, friction between the second valve stem and the camshaft assembly can be reduced, thereby slowing down wear on both. Furthermore, especially when there is a significant difference between the first and second valve lifts, the anti-disengagement spring does not need to provide spring force to ensure contact between the second valve stem and the camshaft assembly when the switchable rocker arm is unlocked. Therefore, the performance requirements for the anti-disengagement spring can be appropriately reduced, simplifying the overall design of the switchable rocker arm.
[0013] In a preferred embodiment, the stop mechanism includes an elastic member and a stop member, wherein, in the unlocked state, the stop member extends partially out of the stop receiving portion disposed in the first or second split arm by means of the elastic member and extends into the corresponding mating stop receiving portion disposed in the second or first split arm.
[0014] Preferably, the elastic element is constructed as a spring, and more preferably a helical compression spring.
[0015] Preferably, the stop is configured as a stop pin. Advantageously, the stop has an end for abutting against or abutting against and guiding the elastic member, such as a flat end or a grooved end.
[0016] Here, the stop receiving portion is constructed in one of the first and second arms, preferably the first arm. Preferably, the stop receiving portion is constructed as a blind hole or groove, and the opening of the stop receiving portion faces the other arm of the first and second arms, preferably the second arm.
[0017] Here, the mating stop receiving portion is constructed at the other arm of the first and second arms, preferably the second arm. Preferably, the mating stop receiving portion is constructed as an opening facing the aforementioned arm, preferably the first arm.
[0018] Here, the positions of the stop receiving portion and the mating stop receiving portion are designed such that, within the range of the stop position of the second split arm, the positions of the stop receiving portion and the mating stop receiving portion correspond to each other, and outside the range of the stop position of the second split arm, the positions of the stop receiving portion and the mating stop receiving portion are at least partially offset.
[0019] Here, the elastic element of the stop mechanism abuts against the stop member at one end and against the bottom of the stop receiving portion, such as the bottom of a blind hole or the bottom of a groove, at the other end.
[0020] When the stop is not in use, the elastic element and the stop element are completely housed in the stop housing.
[0021] When the stop is applied, the stop member extends out of the stop receiving portion and into the mating stop receiving portion by means of the energy storage portion of the elastic member. In other words, the stop member is simultaneously located in the stop receiving portion and the mating stop receiving portion in the stopped state. Optionally, through the matching design of the stop member and the stop receiving portion and the matching design of the stop member and the mating stop receiving portion, the stop member can ensure that the second arm is held, especially completely locked, within the range of the stop position. Optionally, considering the arrangement of the anti-disengagement spring, through the matching design of the stop member and the stop receiving portion or the matching design of the stop member and the mating stop receiving portion, the stop member can ensure that the second arm is held, especially locked, within the range of the stop position in the direction of action of the anti-disengagement spring.
[0022] Particularly preferably, in the locked state, the stop member is held in a stop receiving portion correspondingly disposed in the first or second split arm by means of the second split arm or the first split arm. Specifically, the stop member can be held in the stop receiving portion located in the first split arm by means of the side wall of the second split arm facing the first split arm. Alternatively and specifically, the stop member can be held in the stop receiving portion located in the second split arm by means of the side wall of the first split arm facing the second split arm. Thus, in the locked state of the switchable rocker arm, no additional power is required to the stop mechanism to hold the stop member and the elastic member in the stop receiving portion.
[0023] In a preferred embodiment, the first arm is configured as an inner arm and the second arm is configured as an outer arm, wherein the inner and outer arms are pivotable relative to each other about a pivot axis. Here, the second arm includes two sidewall segments and a transverse segment connecting the two sidewall segments. The first arm is accommodated between the two sidewall segments.
[0024] Optionally, the stop movement path of the stop member is parallel to the pivot axis of the first and second arms that pivot relative to each other. For example, the stop receiving portion and the mating stop receiving portion of the stop mechanism can be respectively provided in a side wall section of the second arm and at the first arm.
[0025] Optionally, the stop movement path of the stop member is perpendicular to the pivot axis of the first and second arms that pivot relative to each other. For example, the stop receiving portion and the mating stop receiving portion of the stop mechanism can be respectively provided in the lateral section of the second arm and the first arm.
[0026] In a preferred embodiment, the locking mechanism includes a locking member capable of locking the first and second arms and an actuator for actuating the locking member, wherein the actuator is at least partially housed in an actuator receiving portion disposed on the second or first arm, the actuator receiving portion serving as a mating stop receiving portion. Preferably, the locking member is configured, for example, as a locking pin. The actuation method of the locking member is not limited herein. The actuator can be driven directly or indirectly by, for example, an electromagnetic or hydraulic device.
[0027] Preferably, when the second split arm is in the stop position, the actuator abuts against the stop member. When the actuator is not loaded, the stop member can push the actuator under the action of the elastic member and partially extend into the actuator receiving portion, which serves as the mating stop receiving portion, thereby implementing the stop. When the actuator is loaded, the stop member overcomes the elastic force of the elastic member under the action of the actuator and moves completely into the stop receiving portion. The actuator here has a dual function: it can both actuate the locking member to lock the switchable rocker arm and reset the stop member back to the stop receiving portion.
[0028] Preferably, the locking movement path of the locking member and the stopping movement path of the stopping member are arranged parallel to each other. In this case, the actuator can efficiently apply force to the target object, i.e., the locking member or the stopping member, in the same movement manner in different operating states.
[0029] By utilizing the stop mechanism provided herein, the second valve arm disengages from the second profile of the cam member in the unlocked state of the switchable rocker arm, thus reducing friction between the second valve arm and the cam member and consequently slowing down wear on both. Furthermore, especially for cases where the two valve lifts differ significantly, the anti-disengagement spring does not need to provide spring force to bring the second valve arm into contact with the cam member in the unlocked state of the switchable rocker arm. Therefore, the performance requirements for the anti-disengagement spring can be appropriately reduced, simplifying the overall design of the switchable rocker arm. Additionally, the stop element in the stop mechanism can be reset using the actuation element of the locking element for the switchable rocker arm, eliminating the need for an additional reset component and allowing for simple implementation of the stop mechanism. Simultaneously, the stop mechanism has minimal impact on other structures of the existing switchable rocker arm, resulting in fewer modifications to the overall design of the switchable rocker arm. Consequently, the design cost of the variable valve mechanism can also be reduced. Attached Figure Description
[0030] Preferred embodiments of the present invention will now be illustrated schematically with reference to the accompanying drawings. The drawings are as follows:
[0031] Figure 1 This is a side view of a switchable rocker arm in a first lift mode according to one embodiment;
[0032] Figure 2 It is based on Figure 1 Side view of the switchable rocker arm in the second lift mode;
[0033] Figure 3 It is based on Figure 1 A schematic cross-sectional view of the stop mechanism of the switchable rocker arm in the first state;
[0034] Figure 4 It is based on Figure 1A schematic cross-sectional view of the stop mechanism of the switchable rocker arm in the second state;
[0035] Figure 5 It is based on Figure 1 A schematic cross-sectional view of the stop mechanism of the switchable rocker arm in the third state; and
[0036] Figure 6 It is based on Figure 1 A schematic cross-sectional view of the stop mechanism of the switchable rocker arm in the second state; Detailed Implementation
[0037] Figure 1 and Figure 2 A perspective view of a switchable rocker arm according to one embodiment in two lift modes is shown. The switchable rocker arm is used to engage with a cam member 1 on the camshaft in a variable valve mechanism. When the camshaft rotates, the switchable rocker arm oscillates under the drive of the cam member 1, thereby adjusting the valve travel.
[0038] The switchable rocker arm according to this embodiment is constructed as a roller rocker arm. Here, the switchable rocker arm includes two arms: a first arm configured as an inner arm 3 and a second arm configured as an outer arm 2. The outer arm 2 has two sidewall sections and a transverse section connecting the two sidewall sections. The inner arm 3 is housed between the two sidewall sections of the outer arm 2. The inner arm 3 and the outer arm 2 are pivotable relative to each other about a pivot axis via a pivot portion 5 arranged on the longitudinal end side of the switchable rocker arm. Furthermore, the switchable rocker arm also includes an anti-disengagement spring tensioned between the inner arm 3 and the outer arm 2.
[0039] The switchable rocker arm includes a locking mechanism 4. The inner arm 3 and outer arm 2 of the switchable rocker arm can achieve different relative positional relationships by means of the locking mechanism 4.
[0040] Figure 1 A side view of the switchable rocker arm in a first lift mode is shown. In this mode, the locking mechanism 4 is unlocked, and the switchable rocker arm with its inner arm 3 abuts against the first profile of the cam member 1. When the camshaft rotates, the switchable rocker arm can cooperate with the cam member 1 to provide, for example, a low-lift first valve lift.
[0041] Figure 2 A side view of the switchable rocker arm in a second lift mode is shown. In this mode, the locking mechanism 4 is locked, and the two side walls of the outer arm 2 of the switchable rocker arm abut against the second profile of the cam member 1. When the camshaft rotates, the switchable rocker arm can cooperate with the cam member 1 to provide, for example, a high-lift second valve lift.
[0042] Figures 4 to 6 A schematic cross-sectional view of the stop mechanism of the switchable rocker arm of this embodiment in different states is shown.
[0043] like Figures 4 to 6 As shown, the locking mechanism 4 includes a locking member 41 capable of locking and unlocking the inner arm 3 and the outer arm 2, and an actuating member 42 for actuating the locking member 41. The locking member is constructed as a locking pin 42. The actuating member is constructed as an actuating piston 42. In the unlocked state, the locking member 42 is fully received in the through hole constructed in the inner arm 3, and the actuating piston 42 is received in one side wall of the outer arm 2. At this time, the inner arm 3 and the outer arm 2 can pivot relative to each other. In the locked state, the loaded actuating piston 42 extends out of the aforementioned side wall of the outer arm 2 and pushes the locking pin 41 partially into a receiving hole located in the other side wall of the outer arm 2. At this time, the inner arm 3 and the outer arm 2 cannot pivot relative to each other or can only pivot within an angular range that does not affect the lift. The locking mechanism 4 also includes a return spring 43. The locking pin 41 can be reset back into the through hole of the inner arm 3 by the return spring 43. A stop sleeve 44 is also provided in the through hole of the inner arm 3 to prevent the locking pin 41 from dislodging from the through hole.
[0044] The switchable rocker arm has a stop mechanism. In the unlocked state of the switchable rocker arm, the outer arm 2 can be stopped at a stop position relative to the inner arm 3 by means of the stop mechanism, and the outer arm 2 disengages from the second profile of the cam member 1 at the stop position.
[0045] In this embodiment, the stop mechanism includes a stop receiving portion and a mating stop receiving portion. The stop receiving portion is constructed as a blind hole in the inner arm 3, the opening of which faces the side wall of the outer arm 2 where the actuating piston 42 is provided. Here, the extending direction of the blind hole serving as the stop receiving portion and the extending direction of the through hole for receiving the locking pin 41 are both parallel to the pivot axis on which the inner arm 3 and the outer arm 2 pivot relative to each other. In this embodiment, the mating stop receiving portion is realized by a receiving hole in the outer arm 2 for receiving the actuating piston 42. The positions of the stop receiving portion and the mating stop receiving portion are designed such that within the range of the stop position of the outer arm 2, the positions of the stop receiving portion and the mating stop receiving portion correspond to each other, and outside the range of the stop position of the outer arm 2, the positions of the stop receiving portion and the mating stop receiving portion are offset. Here, the stop mechanism also includes an elastic element in the form of a helical compression spring 62 and a stop member in the form of a stop pin 61. The helical compression spring 62 has one end against the helical compression spring 62 and the other end against the bottom of the stop receiving part, that is, the bottom of the blind hole.
[0046] The following is combined with Figures 3 to 6 Explain how the stop mechanism works.
[0047] like Figure 1As shown, the switchable rocker arm is in the unlocked state, the locking pin 41 is completely inside the inner arm 3, and the actuating piston 42 does not extend towards the inner arm 3 from the side wall of the outer arm 2. At this time, the outer arm 2 is outside the stop position range, and the locking mechanism does not engage the stop. Here, the stop pin 61 abuts against the side wall of the outer arm 2, thereby the helical compression spring 62 and the stop pin 61 are completely accommodated in the stop receiving portion by means of the outer arm 2.
[0048] When it is necessary to switch to low lift mode, such as Figure 2 As shown, the outer arm 2 can move relative to the inner arm 3 to a stop position under the action of the cam member. The stop pin 61, under the action of the helical compression spring 62, pushes the unloaded actuating piston 42 away from the inner arm 3, thereby partially extending the stop pin 61 into the actuating piston receiving portion, which serves as a mating stop receiving portion, thus implementing the stop. The outer arm 2 is then stopped in the stop position, thereby disengaging from the second profile of the cam member throughout the low-lift mode, reducing friction between the outer arm 2 and the cam member and slowing down wear on both.
[0049] like Figure 3 As shown, when it is necessary to release the stop, the actuating piston 42 can be applied. Under the action of the applied actuating piston 42, the stop pin 61 overcomes the elastic force of the helical compression spring 62 and moves completely back into the stop receiving part, thereby releasing the stop.
[0050] After releasing the stop, as Figure 4 As shown, the outer arm 2 moves relative to the inner arm 3 outside the stop range under the action of the anti-disengagement spring, thereby achieving re-contact with the second profile of the cam member. At this time, the actuating piston 42 moves with the outer arm 2 to the position corresponding to the locking pin 41. In this case, the locking pin 41, under the action of the loaded actuating piston 42, overcomes the elastic force of the return spring 43 and partially moves out of the inner arm 3 and extends into the receiving hole on the other side wall of the outer arm 2. The switchable rocker arm is thus locked, and the switchable valve mechanism is now in the high-lift mode.
[0051] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection for this invention. Therefore, any changes and modifications made to the embodiments described herein based on the innovative concept of this invention, or equivalent structural or procedural transformations made using the description and drawings of this invention, directly or indirectly applying the above technical solutions to other related technical fields, are all included within the scope of protection of this invention.
[0052] List of reference numerals
[0053] 1. Cam component
[0054] 2. Second arm, outer arm
[0055] 3. First split arm, inner arm
[0056] 4. Locking mechanism
[0057] 41 Locking component, locking pin
[0058] 42. Actuator, Actuating Piston
[0059] 43. Return spring
[0060] 44 Stop sleeve
[0061] 5 Pivot section
[0062] 6. Stopping mechanism
[0063] 61. Elastic element, helical compression spring
[0064] 62 Stop component, stop pin
Claims
1. A switchable rocker arm for providing different valve lifts in conjunction with a cam in a variable valve timing mechanism, said switchable rocker arm comprising: The first arm (3) and the second arm (2) are able to move relative to each other; as well as The locking mechanism (4) is capable of locking and unlocking the first arm (3) and the second arm (2). In the unlocked state, the first valve arm (3) contacts the first profile of the mating cam to provide a first valve lift, and in the locked state, the second valve arm (2) contacts the second profile of the mating cam to provide a second valve lift different from the first valve lift. The switchable rocker arm is characterized in that it further includes a stop mechanism (6), wherein, In the unlocked state, the second arm (2) can be stopped at a stop position relative to the first arm (3) by means of the stop mechanism (6), and the second arm (2) disengages from the second profile of the cam at the stop position.
2. The switchable rocker arm according to claim 1, characterized in that, The stopping mechanism (6) includes an elastic element (62) and a stopping element (61), wherein, In the unlocked state, the stop member (61) extends partially out of the stop receiving portion provided in the first split arm (3) or the second split arm (2) by means of the elastic member (62) and extends into the corresponding matching stop receiving portion provided in the second split arm (2) or the first split arm (3).
3. The switchable rocker arm according to claim 2, characterized in that, In the locked state, the stop (61) is held in the stop receiving portion correspondingly provided in the first branch arm (3) or the second branch arm (2) by means of the second branch arm (2) or the first branch arm (3).
4. The switchable rocker arm according to claim 2 or 3, characterized in that, The first arm (3) is constructed as an inner arm and the second arm (2) is constructed as an outer arm, wherein the inner arm and the outer arm are pivotable relative to each other about a pivot axis, wherein, The stop movement path of the stop member (61) is parallel to the pivot axis.
5. The switchable rocker arm according to claim 2 or 3, characterized in that, The first arm (3) is constructed as an inner arm and the second arm (2) is constructed as an outer arm, wherein the inner arm and the outer arm are pivotable relative to each other about a pivot axis, wherein, The stop movement path of the stop member (61) is perpendicular to the pivot axis.
6. The switchable rocker arm according to claim 2 or 3, characterized in that, The locking mechanism includes a locking member (41) capable of locking the first branch arm (3) and the second branch arm (2) and an actuator (42) for actuating the locking member (41), wherein the actuator (42) is at least partially accommodated in an actuator accommodating portion disposed in the second branch arm (2) or the first branch arm (3), the actuator accommodating portion serving as the mating stop accommodating portion.
7. The switchable rocker arm according to claim 6, characterized in that, When the second arm (2) is in the stop position, the actuator (42) abuts against the stop (61).
8. The switchable rocker arm according to claim 6, characterized in that, The locking movement path of the locking member (41) and the stopping movement path of the stop member (61) are set parallel to each other.
9. The switchable rocker arm according to claim 2 or 3, characterized in that, The elastic element is constructed as a spring.
10. The switchable rocker arm according to claim 2 or 3, characterized in that, The stop is constructed as a stop pin.