Switchable rocker arm

Abstract

The switchable rocker arm (1, 2, 3, 4) can include a body (10, 11) configured to rotate about a rocker shaft. The body can include a valve end (102) and a cam end (103) including a piston bore (135, 136). The second body (21, 22, 23, 24) can include a pivot portion (2140, 2240, 2340, 2440), a cam receiving transfer portion (2130, 2230, 2330, 2430), and a latch bore (2132) through the transfer portion. A latch assembly (60) can be mounted in the latch bore. A piston assembly (50) can be mounted in the piston bore.

Description

TECHNICAL FIELD

[0001] The switchable rocker arm is provided with a latch assembly mounted through a transfer portion of the second body. A lost motion spring can be integral with the second body. Several pivot portions are shown as alternatives for pivoting the second body relative to the body. BACKGROUND

[0002] Switchable rocker arms enable variable valve actuation techniques such as cylinder deactivation for internal combustion engines. But it remains problematic to package the switchable functionality in the tight spaces of the machine. SUMMARY

[0003] Switchable rocker arms are shown to enable variable valve actuation techniques such as cylinder deactivation and switching lift events, such as early or late valve opening or closing or high or low relative lift height valve opening or closing (e.g. EEVO, EEVC, LIVC, EIVO, NVO, iEGR, engine braking, etc.). A lightweight design is desired to reduce overall machine weight. Integrated manufacturing is needed for ease of installation in the machine as an original equipment or replacement part. But it remains problematic to package the switchable functionality in the tight spaces of the machine.

[0004] Several switchable rocker arms are shown to meet one or more of the above objectives. Such switchable rocker arms include a body configured to rotate about a rocker shaft. The body can include a valve end and a cam end including a piston bore. A second body can include a pivot portion, a cam receiving transfer portion, and a latch bore through the transfer portion. A latch assembly is mounted in the latch bore. A piston assembly is mounted in the piston bore.

[0005] In additional aspects, the switchable rocker arm can include a cam end bifurcated to form a first arm boundary including a first piston bore and a first end wall and a second arm boundary including a second piston bore and a second end wall. The piston assembly can include a first piston seated in the first piston bore and a second piston seated in the second piston bore. The switchable rocker arm can include a hydraulic supply in the body configured to supply hydraulic fluid to the first piston bore and the second piston bore.

[0006] A lost motion spring can be mounted over the transfer portion. The lost motion spring can have its center of inertia balanced over the transfer portion. A spring plate can be fixed to the cam end to seat the lost motion spring.

[0007] The transfer portion can include a bearing shaft and a roller bearing mounted for rotation on the bearing shaft. The bearing shaft can include the latch bore. The latch assembly can include a first latch and a second latch biased from the latch bore.

[0008] The transfer portion can include a hollow body configured to fit over a bearing shaft. The transfer portion can be further configured to seat an idler spring. The second body can be configured to anchor to the pivot portion. The pivot portion can include a pair of rocker shaft bearings configured to rotate about a rocker shaft. The second arm can include a stamped sheet forming a hollow body, a pivot portion, and a connecting body. The connecting body can span a segment of the main body between a rocker shaft bore and a cam end.

[0009] The switchable rocker arm can include a spring frame including a first prong for abutting the transfer portion, a second prong for abutting the transfer portion, and a spring seat spanning between the first prong and the second prong. The spring frame can cup the transfer portion from a first side, and the second body can include a hollow frame that cups the transfer portion from the first side. Alternatively, the spring frame can cup the transfer portion from the first side, and the second body can include a hollow frame that cups the transfer portion from a second side.

[0010] Objects and advantages will be set forth in part in the following description, will appear from the description, or can be learned from practice of the disclosure. The objects and advantages will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a perspective view of a rocker arm.

[0012] Figure 2 is a perspective view of a rocker arm. Figure 1 is a cross-sectional view of a portion of the rocker arm of

[0013] Figure 3 is a view of a second body.

[0014] Figure 4A and Figure 4B is a comparative view of a second body positioned in a main body, wherein Figure 4B shows an idling position.

[0015] Figure 4AA shows a latching assembly unlatched by a piston assembly. The second body is ready to move relative to the main body.

[0016] Figure 4BB shows the second body moving in an idling direction (indicated by the arrow). The travel stop and travel limit combination limit movement of the second body, which is an option to implement other variable valve lift technologies.

[0017] Figure 5A and Figure 5B shows an alternative second body.

[0018] Figures 6A to 6C An alternative second body is shown.

[0019] Figure 7A and Figure 7B An alternative spring plate, body, and second body are shown. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to the examples shown in the drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0021] Several switchable rocker arms are shown in the figures to meet one or more goals of light weight, integrated assembly, and compact packaging. Such switchable rocker arms 1-4 can include a body 10, 11 configured to rotate about a rocker shaft. The body 10, 11 can include a valve end 102 and a cam end 130. The valve end 102 can include an articulation for acting on a valve stem or valve bridge, or the valve end 102 can include a socket 111 for a capsule or a sleeve for a function such as lash adjustment, engine braking, etc. As shown, the socket 111 includes a lash pin 112, a lash nut 113, and an electronic foot (puppet foot) 114. The cam end 103 can include at least one piston bore 135, 136. Preferably, the cam end 103 is bifurcated to provide two piston bores 135, 136. A second body 21-24 can then be seated to selectively pivot between the bifurcated portions of the cam end 103.

[0022] The second body 21-24 can include a pivot portion 2140, 2240, 2340, 2440, a cam receiving transition portion 2130, 2230, 2330, 2430, and a latch aperture 2132 through the transition portion. A latch assembly 60 is mounted in the latch aperture 2132. A piston assembly 50 is mounted in the at least one piston bore 135, 136.

[0023] The body 10, 11 can be light weight by including a hollow. A rocker shaft bore 101, with or without a bushing, can be included to orient the rocker arm 1-4 on a rocker shaft. The rocker shaft can supply hydraulic fluid to control the piston assembly 50. A hydraulic assembly 150 can be configured with a hydraulic port 151, a hydraulic supply 152, a hydraulic outlet 153, 154, and an optional leak port 155.

[0024] The switchable rocker arm 1-4 can include a cam end 103 that bifurcates to form a first arm boundary 131 including a first piston bore 135 and a first end wall 133, and a second arm boundary 132 including a second piston bore 136 and a second end wall 134. The first end wall 133 and the second end wall 134 can be formed as shown to include first and second piston bushings 53, 54 that fit in the first and second piston bores 135, 136. Alternatively, one or both of the first and second piston bores 135, 136 can be formed as blind holes such that the first and second end walls are integrally formed with the first and second arm boundaries 131, 132. As another option, the first and second arm boundaries 131, 132 can be formed with fastener receptacles 161, 162 or optional alignment posts or other mechanisms to secure the resilient plates 31 or 32.

[0025] The piston assembly 50 can include a first piston 51 seated in the first piston bore 135 and a second piston 52 seated in the second piston bore 136. The switchable rocker arm 1-4 can include a hydraulic supply 152 in the body 10, 11 configured to supply hydraulic fluid to the first and second piston bores 135, 136. The hydraulic supply 152 can include hydraulic outlets 153, 154 in fluid communication with the first and second piston bores 135, 136. As one option, a leak port 155 can be cross-drilled through the first and second piston bores 135, 136. The first and second piston bushings 53, 54 can then also include oil cups 531, 541 for collecting pressurized fluid and oil feeds 532, 542 cross-drilled to receive hydraulic control fluid for controlling the pistons 51, 52. The first and second piston bushings 53, 54 can include inner walls 534, 544 that act as travel stops for the piston ends 515, 516. A gland or other recess or port can optionally be included on the first and second bushings 53, 54 and pistons 51, 52 to facilitate dispensing of hydraulic control fluid. The inner walls 534, 544 can optionally be part of a blind hole variant of the piston bores.

[0026] The pistons 51, 52 can include a piston body 510, 520 having a piston face 511, 521. An optional tab 512, 522 or nose can be included on the piston face 511, 512. The tab 512, 522 can act as a travel stop to cooperate with the travel limit 2161, 2162. A pressure chamber 513, 523 can be included in the piston body 510, 520. A small diameter of the piston 51, 52 can result in low volume of hydraulic control fluid and high response time actuation.

[0027] Instead of an overhead reaction rod, the lost motion spring 40 can be mounted above the transfer portion 2130, 2230, 2330, 2430. The lost motion spring 40 can have its center of inertia balanced above the transfer portion 2130, 2230, 2330, 2430. The spring plates 31, 32 can be fixed to the cam end 103 to seat the lost motion spring 40. The first spring end 41 can be biased against a portion of the second body 21-24, and the second spring end 42 can be biased against the spring plates 31, 32. This biases the second body 21-24 into a position where the latch assembly 60 can latch in the piston bore 135, 136.

[0028] The spring plates 31, 32 can include spring plate ends 311, 312 or 321, 322 that are configured to couple to the diverging body. For example, the first arm boundary 133 and the second arm boundary 134 include fastener receptacles 161, 162 to receive fasteners 261, 262, such as screws or rivets. Alternatively, welds can be used to secure the spring plates 31, 32. Alternatively, prongs, pins, screws, or the like can protrude from the first arm boundary 133 and the second arm boundary 134 to receive a nut or cap. The spring plates 31, 32 can include a lost motion seat 33 with optional protrusions or grooves to position the second spring end 42. Instead of a continuous piece of material, the cage arrangement can have cage arms 323, 324. The spring plate 31 can be straight in a square configuration Figure 1 Figure 2 Figures 4A to 6A Figure 6C ), or the spring plate 32 can be angled in a configuration Figure 7A Figure 7B to skew to provide a trajectory for the spring force of the lost motion spring 40.

[0029] ​​​​The transfer portion 2130, 2230, 2330, 2430 can include a bearing shaft 2131 and a roller bearing 2134 mounted to rotate on the bearing shaft 2131. An optional needle bearing can be included between the roller bearing 2134 and the bearing shaft 2131. A slider bushing integral with the bearing shaft 2131 is an alternative. The bearing shaft 2131 can include a latch hole 2132. The latch assembly 60 can include a first latch 61 and a second latch 62 biased from the latch hole 2132. If only one piston 51 or 52 is used, only one latch 61 or 62 will be needed. A blind hole, snap ring, bushing, or other tether can be used to bias one latch 61 or 62 in the direction of one piston 51 or 52. However, as shown, a latch spring 615 can push the latch end 613, 623 away to form a latch cavity 616. The latch spring 615 can be seated in a spring cup 614, 624 in the latch body 611, 621. The latch face 612, 622 can face the piston 51, 52 to push the piston 51, 52 into the piston hole 135, 136 until hydraulic control fluid is used to collapse the latch spring 615 and abut the latch end 612, 623. Other travel limiters can be used for the latches 61, 62 such as bushings, cast walls, snap rings, etc. With this arrangement, it is possible to have a dry latch hole 2132 without the use of hydraulic control fluid. The second body 21-24 can be lubricated via the hydraulic supply in the piston hole 135, 136 or the body 10, 11, or not at all. The rotating cam can be lubricated via the body 10, 11 but not the second body 21-24, resulting in a lighter, less complex second body 21-24.

[0030] In the first arrangement, the second body 21 can be coupled to the pivot mounts 141, 142 via a pivot shaft 143. The pivot region 140 is proximate to the cam end 103 and is formed by the portion of the body 10 that is connected to the pivot portion 2140 of the second body 21. The second body 21 can include pivot mounts 2141, 2142 to connect to the pivot shaft 143. The transfer portion 2130 can include a hollow body 211 configured as a boxed bearing shaft 2131. The ends 2135, 2136 of the bearing shaft 2131 can be fixed in bearing slots 216, 217. The hollow body can include connecting joists 212, 213 for spanning the transfer portion 2130 and for seating the idle spring 40. Struts 214, 215 can extend from the connecting joists 212, 213 to include the bearing slots 216, 217. Optional platform sockets 218, 219 can extend from the struts 214, 215 or the connecting joists 212, 213 to form a pivot location for the spring platform 3131. The spring platform 3131 can seat the idle spring 40 with optional spring guides 2132, which can alternatively be grooves or other guides. Platform guides 3133, 3134 can extend into the platform sockets 218, 219 to pivot the spring platform 3131. As the idle spring 40 retracts Figure 4BB ) or expands back to the latched position Figure 2 ), the plate portion 2135 can pivot or rock. Thus, the transfer portion 2130 can be configured to seat the idle spring 40. The second body 21 can be configured to anchor to the pivot portion 140. The second arm 21 can include a stamped sheet forming the hollow body 211, the second pivot portion 2140, and the connecting joists 212, 213.

[0031] Figure 2 The latched position of the latching assembly 60 is shown. Figure 4AA The unlatched position is shown, and Figure 4B and Figure 4BB The idle position is shown. Figure 4A A position is shown in which the latching assembly 60 can move between the latched position and the unlatched position. These latching positions can be used with the second bodies 22-24 of Figures 5A to 7B , in which Figure 7B An additional idle position is shown with a cross section of a hollow roller bearing 2134.

[0032] In Figure 5A and Figure 5BIn this embodiment, the transfer portion 2230 can include a hollow frame 221 configured to house the bearing axle 2131. The hollow frame 221 is configured to have connecting joists 222, 223 that house the roller bearing 2134 from the bottom side (second side relative to the spring platform 3131). The struts 224, 225 include bearing slots 226. The assembly method of the bearing axle 2131 can be further reduced. The connecting body 228 extends from the hollow frame 221. The side arms 2282, 2283 extend from the connecting body 228 and can include pivot mounts 2241, 2242 in the form of rocker axle bearings. The pivot mounts 2241, 2242 of the pivot portion 2240 are co-located with the rocker axle hole 101 so that the rocker axle can serve as the pivot location for both the main body 11 and the second body 22. The second body 22 can be formed from stamped sheet material so that the weight is very light. Low cost can be achieved. The transfer portion 2230 can be further configured to seat the lost motion spring 40. The spring platform 2231 can include a plate portion 2237 with optional spring guides 2232. Platform struts 2233, 2234 can extend from the plate portion 2237 with platform support slots 2235. The spring platform 2231 can rest on the bearing axle 2131. The platform bearing slots 2235 can be designed to snap onto the bearing axle 2131. Thus, the second body 22 can be configured to be anchored to the pivot portion 2240, here the rocker axle. The pivot portion 2240 can include a pair of rocker axle bearings as pivot mounts 2241, 2242 configured to rotate about the rocker axle. The second arm 22 can include the stamped sheet material forming the hollow frame 221, the pivot portion (pivot mounts 2241, 2242), and the connecting body 228. The connecting body 228 can span the segment of the main body 11 between the rocker axle hole 101 and the cam end 103. The spring frame (spring platform 2231) can cup the transfer portion 2230 from the first side, and the second body 22 can include the hollow frame 221 that cups the transfer portion 2230 from the second side.

[0033] In Figure 6A and Figure 6BIn this embodiment, the transfer portion 2330 can include a hollow body 231 configured to fit over the bearing axle 2131. The hollow body 231 is configured to have connecting beams 232, 233 that fit over the roller bearing 2134 from the top side (first side relative to the spring platform 2231). Struts 234, 2324, 235, 2325 are attached to the beams 239, 2329 to form a bearing slot 236. The assembly method of the bearing axle 2131 can be further reduced. A connecting body 238 extends from the hollow body 231. A bracket 2381 extends upward over a portion of the main body 11. Side arms 2382, 2383 extend from the bracket 2381 of the connecting body 238 and can include pivot mounts 2341, 2342 in the form of swing arm axle bearings. The pivot mounts 2341, 2342 of the pivot portion 2340 are co-located with the swing arm axle hole 101 so that the swing arm axle can serve as a pivot location for both the main body 11 and the second body 23. The second body 23 can be formed from stamped sheet material so that the weight is very light. Low cost can be achieved. The transfer portion 2330 can be further configured to seat the lost motion spring 40. The spring platform 2231 can be configured as above. The spring platform 2231 can drop over the bearing axle 2131. The platform bearing slot 2235 can be designed to snap over the bearing axle 2131. Thus, the second body 23 can be configured to be anchored to the pivot portion 2340, here the swing arm axle. The pivot portion 2340 can include a pair of swing arm axle bearings as pivot mounts 2341, 2342 configured to rotate about the swing arm axle. The second arm 23 can include the stamped sheet material forming the hollow body 231, the pivot portion (pivot mounts 2341, 2342), and the connecting body 238. The connecting body 238 can span a segment of the main body 11 between the swing arm axle hole 101 and the cam end 103. The spring frame (spring platform 2231) can include a first prong formed by the platform strut 2233 for abutting the transfer portion 2330, a second prong formed by the strut 2234 for abutting the transfer portion 2230, and a spring seat formed by the plate portion 2237 spanning between the first and second prongs. The spring frame (spring platform 2231) can cup the transfer portion 2230 from the first side, and the second body 23 can include a hollow frame 231 that cups the transfer portion 2230 from the first side.

[0034] The main body 10 can be used with the second main body 24. The pivot portion 140 can be proximate to the rocker shaft hole 101, but not overlapping the rocker shaft hole 101. Material utilization efficiency can result in the second main body 24 exiting below the rocker shaft hole 101 at an angle. The spring plate 31 can then be set at an angle or deflected so that it positions the lost motion spring 40 to bias the latch hole 2132, thereby aligning the latches 51, 52 with the piston holes 135, 136. Similar to the cover 310, the cover 320 can form the spring guide 33. To match the angle of the spring plate 32, the hollow body 241 of the second main body 24 can include an angled spring platform 2431. The struts 224, 225 can also be angled. The transfer portion 2430 can include the hollow body 241 configured to fit the bearing shaft 2131. The transfer portion 2430 can be configured to seat the lost motion spring 40. The second main body 24 can be configured to be anchored to the pivot portion 2440. The pivot portion 2440 can include a pair of primary pivot mounts 141 connected to a pair of secondary pivot mounts 2441 via a pivot shaft 143. The second arm 24 can include a stamped sheet forming the hollow body 241, pivot portion (secondary pivot mounts 2441).

[0035] While the stamped sheet is shaped for the hollow body or hollow frame 211, 221, 231, 241, machining, cold forming, casting, and other techniques can be used to form the components. When cast, the inserts and attachments can act as bushings, bearings, or retainers.

[0036] Other implementations will be apparent to those skilled in the art from consideration of the specification and practice of the examples disclosed herein.

Claims

1. A switchable rocker arm comprising: a body configured to rotate about a rocker shaft, the body comprising: a valve end; and a cam end that diverges to form a first arm boundary and a second arm boundary, the first arm boundary comprising a first piston bore and a first end wall, the second arm boundary comprising a second piston bore and a second end wall; a second body comprising: a pivot portion; a cam receiving transfer portion; and a latch bore through the cam receiving transfer portion; a latch assembly mounted in the latch bore; and a piston assembly mounted in one or more of the first piston bore or the second piston bore.

2. The switchable rocker arm of claim 1, wherein the piston assembly comprises a first piston seated in the first piston bore and a second piston seated in the second piston bore.

3. The switchable rocker arm of claim 2, wherein the body comprises a hydraulic supply configured to supply hydraulic fluid to the first piston bore and the second piston bore.

4. The switchable rocker arm of claim 1 or 2, comprising a lost motion spring mounted over the cam receiving transfer portion.

5. The switchable rocker arm of claim 1 or 2, comprising a lost motion spring that balances a center of inertia over the cam receiving transfer portion.

6. The switchable rocker arm of claim 1 or 2, comprising a spring plate secured to the cam end and seating a lost motion spring.

7. The switchable rocker arm of claim 1 or 2, wherein the cam receiving transfer portion comprises a bearing shaft and a roller bearing mounted for rotation on the bearing shaft.

8. The switchable rocker arm of claim 7, wherein the bearing shaft comprises the latch bore, and wherein the latch assembly comprises a first latch and a second latch biased from the latch bore.

9. The switchable rocker arm of claim 7, wherein the cam receiving transfer portion comprises a hollow body configured to frame the bearing shaft.

10. The switchable rocker arm of claim 9, wherein the cam receiving transfer portion is further configured to seat a lost motion spring.

11. The switchable rocker arm of claim 9, wherein the second body is configured to anchor to the pivot portion.

12. The switchable rocker arm of claim 9, wherein the pivot portion comprises a pair of rocker shaft bearings configured to rotate about the rocker shaft.

13. The switchable rocker arm of claim 1, wherein the second body comprises a stamped sheet forming a hollow body, the pivot portion, and a connecting body.

14. The switchable rocker arm of claim 13, wherein the connecting body spans a segment of the body between a rocker shaft bore and the cam end.

15. The switchable rocker arm of claim 1 or 13, further comprising a spring frame comprising: a first prong for abutting the cam receiving transfer portion; a second prong for abutting the cam receiving transfer portion; and a spring seat spanning between the first prong and the second prong. ​ 16. The switchable rocker arm of claim 15, wherein the spring frame cups the cam receiving transfer portion from a first side, and wherein the second body includes a hollow frame that cups the cam receiving transfer portion from the first side.

17. The switchable rocker arm of claim 15, wherein the spring frame cups the cam receiving transfer portion from a first side, and wherein the second body includes a hollow frame that cups the cam receiving transfer portion from a second side.

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