JP3338454B2 - Compression force release device for multi-cylinder engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present application filed with provisional patent application No. 60 filed on January 14, 1997
Claim the advantages of U.S. Pat.

FIELD OF THE INVENTION The present invention relates generally to internal combustion engines, and more particularly, to a compression release apparatus for reducing compression in one or more cylinders of an internal combustion engine during startup. About.

BACKGROUND OF THE INVENTION It is known to use a D-shaped shaft in combination with a flyweight during engine start-up to partially release the compressive force in the combustion chamber by lifting a valve tappet provided in a valve actuation system. Have been. US Patent No. granted to oleksy
No. 5,197,422 is an example. However, Olexi's device cannot be used to reduce the compressive force in one or more cylinders.

SUMMARY OF THE INVENTION The present invention relates to a centrifugal responsive compression release device for reducing compression in a plurality of combustion chambers of an engine having a camshaft. The compression force release device is particularly suitable for reducing the compression force of two cylinders of a V-type two-cylinder engine, but can also be applied to release the compression force of two or more cylinders of an engine.

The compression release device uses a single lift member capable of engaging the two valve actuators and a centrifugal force responsive means (eg, flyweight) for changing the position of the lift member in response to engine speed. Good. The two valve actuators may be arranged at two distinctly different angular positions with respect to the longitudinal axis of the camshaft. Further, the device may use a single shaft that is engageable with the lift member and can be actuated by centrifugal force responsive means. In one embodiment, the centrifugal force responsive means includes a single flyweight, and a single shaft is integrally formed with the flyweight.

In another aspect, the compression release device may use a single shaft and a plurality of lift members each engageable with a different valve actuator. A single shaft is engageable with the plurality of lift members and is positioned substantially outside the camshaft.

In some embodiments of the present invention, the compression release device uses a lift member positioned substantially around and near the outer surface of the camshaft. In some embodiments, the camshaft has a guideway and the lift member is at least partially received in the guideway. In another embodiment, an elongated portion of the lift member is at least partially received within the guideway.

In one particular embodiment of the present invention, a single shaft can engage a single lift member at the D-shaped portion of the shaft. The lift member has two prongs with bearing surfaces that engage the bottom surface of the valve tappet. The lift member is preferably U-shaped and can be located in a guideway (eg, a slot, gap, or hole) through the camshaft, or can be located around the camshaft. At engine starting speed, a single shaft lifts and separates each exhaust valve from the valve seat during a particular period of the compression phase of the engine cycle, so that the lifting member allows the two prongs to engage the valve tappet. Position. As the engine speed increases, the flyweight moves away from the camshaft, thereby rotating the shaft attached to the weight and bringing the flat side of the D-shaped shaft portion adjacent the lift member. As a result, the lift member is pushed away from the valve tappet during rotation of the crankshaft, and thus does not affect valve seating at the operating speed of the engine.

In a variant of the invention, the engine has at least one cam lobe formed from at least two laminates mounted on a camshaft, and the device is formed from one of the at least two laminates. At least one lifting member is used. A single shaft can engage the lift member, which is movable with respect to the other stack for engaging the valve actuator.

In yet another embodiment of the present invention, the compression release device uses a single flyweight, a single release shaft, and two lift pins as lift members. A single release shaft provides for both lift pins, even if the lift pins are located at different positions along the length of the camshaft and at different angular positions with respect to the longitudinal axis of the camshaft. Is activated.

In yet another embodiment of the present invention, the compression release device uses two lift members engageable with a single shaft. The shaft has two planar portions on which the lift member rests when the device is in the disengaged position.

In yet another embodiment of the invention, the compression release device uses a single flat crescent lift member with two bearing surfaces for engaging a valve tappet. When the D-shaped shaft section is rotated, the lift member pivots about the pin connection to engage the bearing surface with the two valve tappets.

In yet another embodiment of the invention, the compression release device uses a single lift member and a single release shaft with a crankpin connected to the lift member. The crank pin is
The lift member is moved when the release shaft rotates.

In yet another embodiment of the present invention, the compression release device uses a single flat lift member with two prongs positioned on the same plane transverse to the camshaft. The top of each prong is provided with an extended planar portion having a bearing surface for engaging a respective valve tappet.

It is a feature and advantage of the present invention to provide a centrifugal responsive compression release device for reducing compression in one or more cylinders of an internal combustion chamber.

It is a feature and advantage of the present invention to provide a centrifugal responsive compression release device that acts on one or more valve actuators to hold an exhaust valve open during a particular period of an engine cycle. is there.

It is a feature and advantage of the present invention to provide a centrifugal responsive compression release device operable to release compression within two cylinders of a V-cylinder engine.

It is a feature and advantage of the present invention to provide a centrifugal responsive compression release device that is applicable to release compression within two or more cylinders of an internal combustion engine.

It is a feature and advantage of the present invention to provide a compression release device that requires a minimum number of parts to operate one or more valve actuators of an internal combustion engine.

A feature and advantage of the present invention is to provide a compression release device that uses a single flyweight to change the position of one or more valve actuators in response to engine speed.

It is a feature and advantage of the present invention to provide a centrifugal responsive compression release device that uses three or less movable members to change the position of one or more valve actuators in response to engine speed. It is.

A feature and advantage of the present invention is a centrifugal responsive compression using a single shaft and one or more lift members to change the position of one or more valve actuators in response to engine speed. The purpose is to provide a force release device.

It is a feature and advantage of the present invention to provide an inexpensive and low-compression force-releasing device for reducing the compressive force in one or more cylinders of an internal combustion chamber.

A feature and advantage of the present invention is that it provides a compression release device that requires less action to release the compression force in one or more cylinders of the internal combustion shaft than prior art compression release devices. It is.

It is a feature and advantage of the present invention to provide a compression release device that operates with reduced motion and has a relatively low kickout speed.

These and other features and advantages of the present invention will become apparent to those skilled in the art from the following description of preferred embodiments and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a first embodiment of a compression force release device according to the present invention using a single flyweight, a single release shaft, and a single U-shaped lift member. is there.

FIG. 2 is a side view of the compression release device taken along line 2-2 of FIG.

 FIG. 3 is a bottom view of the compression force releasing device of FIG.

Fig. 4 shows the inner part of the release shaft and the flyweight received in the bore of the cam gear, 4-4 of Fig. 2;
It is sectional drawing along the line.

FIG. 5 is a schematic view of a U-shaped lift member having two prongs according to the first embodiment of the present invention.

FIG. 6 is a sectional view of the first embodiment of FIG. 1 showing the compression release device in an engaged position.

FIG. 7 is a sectional view of the first embodiment, showing the compression force releasing device in an engaged position.

FIG. 8 is a sectional view of the first embodiment, showing the compression force releasing device of the first embodiment in the disengaged position.

FIG. 9 is a cross-sectional view of the first embodiment showing the compression force releasing device in the disengaged position.

FIG. 10 is a side view of a portion of the second embodiment of the present invention disposed between two cam lobes with the compression release device in the disengaged position.

FIG. 11 is a cross-sectional view taken along line 11-11 of FIG. 10 showing two prongs positioned around the camshaft.

FIG. 12 is a cross-sectional view of the second embodiment of the present invention, showing the two-prong lift member and the crank pin in the engaged position.

FIG. 13 is a side view of a cam lobe made of a laminate used in the third embodiment of the present invention.

FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. 13 showing the lift member laminate having a raised portion with a bearing surface adapted to engage a valve tappet.

FIG. 15 is a cross-sectional view of the third embodiment of the present invention, showing the compression release device in the engaged position.

FIG. 16 is a side view of a cam lobe portion of a fourth embodiment of the present invention, wherein the compression release device uses two lift pins received in holes drilled in the camshaft.

FIG. 17 shows the compression release device in the disengaged position,
FIG. 17 is a sectional view taken along line 17-17 in FIG. 16;

FIG. 18 is a cross-sectional view taken along line 18-18 of FIG. 16, showing the second lift pin with the base resting on the second planar portion of the release shaft.

FIG. 19 is a cross-sectional view of a fifth embodiment of the present invention in which the compression release device uses two lift pins.

FIG. 20 is a sectional view of the fifth embodiment of the present invention, showing the compression releasing device in the engaged position.

 FIG. 21 is a sectional view of a sixth embodiment of the present invention.

FIG. 22 is a sectional view of the sixth embodiment of the present invention, showing the compression releasing device in the engaged position.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a centrifugal responsive compression force release device for reducing compression force in one or more cylinders of an internal combustion engine during engine startup. While the device is particularly suitable for reducing the compressive force in the two cylinders of a V-cylinder engine, the present invention extends the release shaft and uses two or more additional lift members. By,
It can be applied to release the compression force of two or more cylinders.

Generally, the compression release device according to the invention is moved by the release shaft to change the position of the centrifugal force responsive means, a single release shaft operable by this means, and at least two valve actuators. At least one lift member.

Referring to FIG. 1, the compression release device 2 is positioned adjacent to a rotatable camshaft 6 located within an engine housing (not shown). This camshaft has an outer end 6a and an inner end 6b. Camshaft 6
A cam gear 8 is attached to the inner end 6b of the cam. The camshaft 6 is further provided with two cam lobes 10, 12 (hereinafter referred to as "inner cam lobe" 10 and "outer cam lobe" 12) which can rotate with the cam shaft. Each cam lobe 10, 12 has a cam 10a, 12a, respectively, which engages with a respective valve actuator (not shown), each including a valve tappet, with a respective combustion chamber (not shown). Activate each associated exhaust valve.

In the first embodiment of the present invention shown in FIGS. 1 to 9, the release shaft 20 is located near the outer surface of the camshaft 6. The release shaft 20 extends from the cam gear 8 through a hole in the inner cam lobe 10. The release shaft 20 has a D-shaped portion 24. This portion extends from the outside of the cam gear 8. The D-shaped shaft portion 24 has a flat portion or surface 24a with a reduced radial length and a rounded or curved surface 24b with a larger radial length. The D-shaped shaft portion 24 can engage a U-shaped lift member 26 having two prongs 26a, 26b. These prongs are adapted to lift the two valve tappets 14, 16 respectively during rotation of the D-shaped shaft portion 24 (second
See figure). The lift member 26 is preferably U-shaped, but other shapes may be used. U-shaped lift member 26
May be located in a guideway (eg, a slot, gap, or hole) provided in or around the camshaft 6 or may be located around the outer surface of the camshaft 6. .

At the starting speed of the engine, the curved portion 24b of the D-shaped shaft portion 24 engages the U-shaped lift member 26 and urges the prongs 26a, 26b toward the valve tappets 14, 16, whereby the respective associated The exhaust valves are each lifted from the valve seat (see FIG. 6). As the engine speed increases, the centrifugal force responsive means, in this case fly weight 28, moves away from the camshaft 6, thereby causing the release shaft 20 attached to the fly weight to rotate, causing the D-shaped shaft portion 24 to rotate. The flat portion 24a is adjacent to the U-shaped lift member 26 (see FIG. 8). As a result, the U-shaped lift member 26 is moved away by the valve tappets 14, 16 during rotation of the crankshaft, and thus does not affect the seating of the exhaust valve at the operating speed of the engine.

1, 2 and 6 show the compression release device 2 in the engaged position at engine start speed. In the engaged position, as best shown in FIG.
The curved portion 24b of the U-shaped lift member 26 engages with each of the prongs 26a, 26b of the U-shaped lift member 26 to lift the valve tappet 14, 16 from the cams 10a, 10b by a linear distance "X".

The compression force releasing device 2 according to the present invention has a
The flyweights 28 are designed to kickout or disengage sufficiently to move radially outward at engine speeds of m, but this preferably occurs at 650-800 rpm. FIG. 8 is a sectional view of the compression force releasing device 2 when the engine is operating at a speed exceeding the kickout speed. The compression release device 2 is in the disengaged position, in which position the flyweight 28
Have been moved radially outward from the camshaft 6 to rotate the release shaft 20. In this figure, the U-shaped lift member 26 has a D-shaped shaft portion 24.
The valve tappets 14 and 16 are
It is substantially disengaged from the prongs 26a, 26b.

FIG. 4 shows the inner end 20a of the release shaft 20 received in the bore 30 of the cam gear 8. On the front side of the cam gear 8, the D-shaped part 24 of the release shaft 20 is also received in a flyweight hole 32 of a flyweight 28. The release shaft 20 is notched at the flyweight hole 32
34, this section engages the bush 36, the bush 36
Hold. The bush has a sleeve portion 38 received in the bore 32. The sleeve portion has an inner surface 38a that engages the knurled section 34 and an outer surface 38b that engages the flyweight 28. As the flyweight 28 moves radially outward, it rotates the sleeve portion 38, thereby rotating the release shaft 20.

With reference to the side view of FIG. 2, the release shaft 20 is further received in the bore 22 of the inner cam lobe 10 and the bores 30, 32 of the cam gear 8 and flyweight 28, respectively. The release shaft 20 may have its inner end 20a interconnected to the camshaft 6 instead of the cam gear 8. It will also be apparent to one skilled in the art to apply the compression release device of the present invention to camshafts of different configurations.

In FIGS. 2 and 3, the bush 36 further has a shoulder 42, on which a torsion spring 44 with several turns is mounted. This spring 44 applies a pressing force to the flyweight 28, and when the engine speed is sufficiently reduced,
A means is provided for rotating the flyweight from its radially extended position to a rest position adjacent to the camshaft. The spring 44 is disposed around the release shaft 20 between the flyweight 28 and the cam gear 6. The first end 44a of the spring 44 is attached to the flyweight 28 (see FIG. 7). The second end 44b of the spring 44 rests on the plane 48a of the camshaft 6 (see FIGS. 3 and 7). Alternatively, instead of a spring, a counterweight or other means for returning the flyweight to its rest position may be used.

FIG. 7 shows the fly weight 28 when the engine is at the starting speed, that is, when the compression release device 2 is in the engaged position.
It is sectional drawing which shows the position. In the engaged position, the flyweight 28 of the compression release device 2 rests adjacent to the camshaft 6. The flyweight 28 has an axially positioned, generally oval-shaped flyweight section 46 in which a flyweight hole 32 for receiving the release shaft 20 is located. Near the flyweight 28, the camshaft 6 has a recess 48 for receiving a flyweight section 46, into which the flyweight section 46 moves. Further, the recess 48 allows the release shaft 20 to approach the camshaft 6 so that it can pass through the inner cam lobe 10 and engage the U-shaped lift member 26. The engagement between the sleeve 38 and the knurled section 34 causes the flyweight 28 to rotate the release shaft 20 when moved radially outward by centrifugal force. Alternatively, two knobs or other locking means may be provided, rather than the notched section being provided throughout.

In a variant, the release shaft may have a circular cross section, and the flyweight may have a completely circular hole for receiving and driving rotation of the release shaft.
In yet another embodiment, the release shaft may have a rectangular cross section that engages the flyweight hole. In yet another embodiment, the flyweight may be fixed directly to the release shaft by a set screw or other fastening means.

The flyweight may be formed by stamping a steel sheet or from a powdered metal and has a nylon bush. In one particular embodiment, the flyweight and release shaft are integrally formed in one piece from a single metal piece. In another embodiment, a one-piece flyweight-release shaft configuration is combined with a U-shaped lift member 26 shown in FIG. 5, thereby providing a compression release device comprising two movable components.

FIG. 9 is a sectional view showing the position of the fly weight 28 when the compression force releasing device 2 is at the disengaged position. The fly weight 28 is moved radially outward to apply a pressing force to the spring 44. In this position, flyweight section 46
Engages with the concave surface 48a of the camshaft 6, thereby stopping the flyweight 28 from moving further.

FIG. 5 shows one of several embodiments of a lift member according to the present invention. Lift member 26 is substantially U-shaped and includes a pair of rod-shaped prongs 26a and 26d connected by a bridge member 26c. 1st prong 26a
Is associated with the inner cam lobe 10 and the first valve tappet 14 (see also FIG. 2). 2nd prong 26
b is associated with the outer cam lobe 12 and the second valve tappet 16 (see also FIG. 2). The U-shaped member may be made of mild steel or pre-hardened "piano wire". One source of pre-cured piano wire is
Rockford Springs, Rockford, Illinois.

Referring to FIGS. 5 and 6, the prongs 26a, 26b
Are received in guideways or holes 50a, 50b drilled in the camshaft 6, respectively. Each of these prongs 26a, 26b has a bearing surface 52a, 52b adapted to engage the bottom surface 14a, 14b of the valve tappet 14,16. Each bearing surface 52
a, 52b are planes corresponding to the orientation of the bottom surfaces 14a, 14b of the valve tappets 14, 16 when engaged with these bearing surfaces. During rotation of the release shaft 20 (due to the movement of the flyweight 28), the prongs 26a, 26b move within the holes 50a, 50b,
Engage and disengage with the valve tappets 14,16. In a variant, each bearing surface may be dome-shaped so as to form the curved surface of the end view in FIG. 6, ie it may be rounded. In an alternative embodiment, instead of holes 50a, 50b, slots or notches provided in the camshaft may be used to receive the prongs, and the prongs may be used to position the bearing surface to engage the valve tappet. May be formed so as to be wound around the camshaft. From FIG. 6, holes 50a and 50b are inserted into camshaft 6 so as not to hit oil port 54 at the center of camshaft 6.
Note that it is positioned at

Next, referring to the side view of FIG.
6b, the bearing surfaces 52a, 52b are the bottom surfaces 14a, 16a of the valve tappet.
The camshaft 6 between the cam lobes 10 and 12 to engage
Are positioned along the length of Referring to the sectional view of FIG. 6, the holes of the prongs 26a, 26b and the camshaft 6 are shown.
50a, 50b also have a bearing surface 52a, 52b with a valve tappet 14,
It is positioned to engage with 16. To accommodate this position, the bridge portion 26c has a plurality of bends and extensions for guiding over the outer surface of the camshaft 6 between the inner cam lobe 10 and the outer cam lobe 12. Referring to the bottom view of FIG. 3 and the cross-sectional view of FIG.
c functions to align each prong 26a, 26b with one of the holes 50a, 50b and one of the valve tappets 14,16. Further, the U-shaped lift member 26 is positioned substantially adjacent to the outer surface of the camshaft 6.

With reference to FIGS. 2 and 3, the outer end 20b of the release shaft 20 is received in the bore 22 of the inner cam lobe 10, passes through the inner cam lobe 10, and extends near the middle bend 26d of the bridge portion 26c. Engage with the U-shaped lift member 26. Between the cam lobes 10, 12, the camshaft 6 has been modified to have a recess 56 for receiving the bridge portion 26c of the U-shaped lift member 26. In the engaged position shown in FIG. 6, the bridge portion 26c is lifted by the curved surface portion 24D of the D-shaped shaft portion 24,
It is substantially engaged with the concave surface 56a of the camshaft 6. The D-shaped shaft section 24 starts outside the cam gear 8.

FIGS. 10 to 12 show a second embodiment of the present invention, in which the compression releasing device 102 comprises two prongs 1.
A single U-shaped lift member 126 with 26a, 126b and a release shaft 120 with crankpins 160 for moving the lift member 126 in response to engine speed are used. The U-shaped lift member 126 further has a bridge portion 126c connecting the two prongs 126a, 126b. However, in this embodiment, the prongs 126a, 126b are both positioned in a common plane substantially transverse to the longitudinal axis of the camshaft 6. Therefore, the bridge portion 126c does not require a large number of bends as in the first embodiment. Instead, the bridge portion 126c only traverses the camshaft 6 to connect the two prongs 126a, 126b. Prong 126a of the second embodiment,
126b is slat-shaped and is received in the guideway or slot 160a, 160b of the camshaft 6. However, these prongs may be rod-shaped as in the first embodiment and may be received in holes in the camshaft.

Referring to FIGS. 11 and 12, each prong 126a, 12
6b is the top bend 16 forming the extended bearing surface portions 166, 168
It has 2,164. Each bearing surface part 166, 168 has a cam lobe
It extends toward one of 10, 12 to a position below the valve tappet. When the device 102 is in the engaged position, the bearing surfaces 152a, 152b of each bearing surface portion 166, 168 engage the bottom surface of the valve tappet and lift the bubble tappet. In yet another embodiment, the prongs are positioned between the cam lobes 10 and 12 at other locations along the length of the camshaft 6. In these embodiments, one or both of the bearing surface portions may be extended to compensate for the linear distance between the valve tappets.

In yet another embodiment of the U-shaped lift member, the lift member is formed from three separate parts. These parts are
A bridge portion formed by stamping that can engage two pins with a top bearing surface and a D-shaped shaft portion. Two pins are attached to the punched bridge portion by press fitting or the like, and a bearing surface is attached to this. In this example,
The two pins are not in the same plane substantially transverse to the longitudinal axis of the camshaft. A bridge portion extends across the diameter and length of the camshaft to connect the two pins.

Another feature of the second embodiment is that the outer end 120 of the release shaft 120
This is a crank pin 160 provided in b. Crank pin 16
0 is the outer section 17 of the lift member 126 below the bridge portion 126c.
It is received in a hole 170 provided in 2. As the release shaft 120 rotates, the U-shaped lift member 126 is linearly moved a predetermined distance by the crank pin 160, so that the bearing surfaces 152a, 152b engage and lift the valve tappet. In yet another embodiment, a D-shaped portion similar to that used in the first embodiment is used in place of the crankpin of the second embodiment.

11 and 12 show the U-shaped lift member 126 and the crank pin 160 at the disengaged position and the engaged position, respectively. 11 shows the two prongs 126a, 126b positioned around the camshaft 6 and the bridge portion 126c under the recess 148 in the camshaft 6. FIG. FIG. 12 shows the lift member 126 and the crank pin 160 in the engaged position. The crank pin 160 linearly moves the two prongs 126a, 126b a predetermined distance and engages the valve tappet, so that the bridge portion 126c approaches the concave surface 148 of the camshaft 6.

13 to 15 show a third compressive force releasing device 202 embodying the present invention. In this embodiment, device 202 uses a single release shaft 220 to operate two separate lift members 226, 227 of the engine. Here, the cam lobes 210, 212 are formed from a series of concentric laminates formed by stamping. Each of the lift members 226, 227 is a single laminate movably disposed between the stamped laminates of the cam lobes 210, 212. Release shaft 220
Are arranged along a longitudinal axis centered between the two cam lobes 210, 212 (see FIGS. 14 and 15), so that the release shaft 220 is positioned as shown in FIG. , May be received in holes 240, 241 of each cam lobe 210, 212. Another feature is that the release shaft 220 has two separate D-shaped shaft portions 224, 225, each of which is engageable with one of the lift member stacks 226, 227, respectively. . One D-shaped shaft portion 224 is located in the hole 240 of the inner cam lobe 210 and the other D-shaped shaft portion 225 is
They are arranged in twelve holes 241.

Each of the lift member laminates 226 and 227 is
It moves freely up and down between the 0,212 stacks, this movement being limited only by the camshaft 6 and the D-shaped shaft sections 224,225. As shown in FIG. 15, each lift member stack 226, 227 has a raised outer portion 260, 262 having a bearing surface 252a, 252b adapted to engage the bottom surface of the valve tappet. Further, each lift member laminate 226, 2
27 further has an open central section 264 for providing clearance around the camshaft 6. When the device 202 is in the disengaged position as shown in FIG. 13, and when the device 202 is in the disengaged position as shown in FIG.
The movement of the lift member stacks 226, 227 due to the rotation of the D-shaped shaft portions 224, 225 is absorbed. Lift member laminate 22
Each of the 6, 227 is further provided with a lower notch 266 for receiving and engaging the D-shaped shaft portions 224, 225.

16 to 18 show a further compression releasing device 302 embodying the present invention. In this fourth embodiment of the invention, the device 302 again uses a single release shaft 320 to operate two separate lifting members 326,327.
The release shaft 320 is centered between the two cam lobes 10, 12 and extends through the outer cam lobe 12 as well as the inner cam lobe 10. The lift members 326, 327 are lift pins 326, 327 received in guideways or holes 368, 370 drilled in the camshaft 6. In this embodiment, each lift pin 32
The bearing surfaces 352a, 352b located at the top of 6,327 have a dome shape. However, the lift pin of this embodiment
Note that any of the flat bearing surfaces disclosed in the embodiments described above can be applied for use at 326, 327.

In addition, each of these lift pins is
It further has enlarged bases 372, 374 for engaging with zero.
Another feature of this embodiment is that two planar portions on which the enlarged bases 372, 374 rest when the device 302 is in the disengaged position.
That is, 376 and 378 are provided on the release shaft 320. These planar portions 376, 378 are not coplanar, but are each substantially perpendicular to the axis of the hole 368, 370 through which the lift pins 326, 327 move. In the cross-sectional view of FIG. 17, the compression force releasing device 302 is in the disengaged position and the inner lift pin 3
The 26 enlarged base 372 is the first flat portion 37 of the release shaft 320.
It is put on 6. In the sectional view of FIG. 18, the outer lift pins 3
The enlarged base 374 of the 27 is the second flat portion 37 of the release shaft 320.
It is put on 8. When the device 320 is in the engaged position, the enlarged bases 372, 374 engage with two different ridges or rounded portions 380, 382 of the release shaft 320. In a variant, one or both of the enlarged bases are reshaped so that the bottom surfaces of both enlarged bases are coplanar with the other bottom surface.
In such an embodiment, the bottom surfaces can engage only one planar portion of the shaft, which planar portion extends between the two bases.

16-18, the release shaft 320 is shown as extending through the outer cam lobe 12, but the release shaft 320 need not extend through the outer cam lobe 12, and It is clear from FIG. 16 that the terminal may be terminated at the lower part. However, depending on the engine, the configuration shown in FIG. 16 provides greater stability and accuracy to the compression release device 302.

19 and 20 show a fifth compressive force release device 402 embodying the present invention. In this fifth embodiment, the compression release device 402 operates the two lift pins 426, 427
A single release shaft 420 having a U-shaped shaft portion 424 is used. Each of the two lift pins 426, 427 is provided with a footer 460, 462. These footers have a centrally located D-shaped shaft section
Extending towards 424. As in the fourth embodiment of the present invention, the lift pins 426, 427 of this embodiment are received in guideways or holes 468, 470 drilled in the camshaft 6 and have domed bearing surfaces 452a, 452b. However, unlike the fourth embodiment, the D-shaped shaft portion 424
Has a single planar portion 424a on which the extended footers 460, 462 rest when the compression release device 402 is in the disengaged position (see FIG. 19). Fig. 20 shows the compression release device
Two lift pins 426, 42 when 402 is in the engaged position
7, and the location of the D-shaped shaft portion 424.

FIG. 21 and FIG. 22 show a sixth compression releasing device 502 embodying the present invention. The device 502 in this embodiment uses a single release shaft 520 with a D-shaped shaft portion 524 and a single flat crescent lift member 526 positioned between the two cam lobes 10,12. The crescent-shaped lift member 526 has a pair of raised portions 564 and 566 as the first.
Provided on the arcuate segment 560, these portions have extended bearing surfaces for engaging the valve tappet.
568 and 570 are provided. Crescent lift member 526
Also has a central section 572 shaped to provide a clearance around the camshaft 6. The central section 572 is provided with a hole 574 for receiving and engaging the D-shaped shaft portion 524. Crescent lift member 526
Is a second arcuate segment 562 provided with a pivot pin 576.
It further has. When the D-shaped shaft portion 524 rotates, the lift member 526 pivots about the pivot pin 576,
The raised portions 564 and 566 move outward, and the bearing surface 56
8,570 engage the valve tappet (see FIG. 22). No.
21 and 22 show the gap between the camshaft and the crescent lift member 526 at two positions on the compression release device 502. FIG.

While several embodiments of the present invention have been illustrated and described, modifications to these embodiments will be apparent to those skilled in the art. Such modifications are within the intended scope of the present invention. Accordingly, the invention is limited only by the following claims.

Continuation of the front page (56) References JP-A-2-67409 (JP, A) JP 47-1850 (JP, Y1) JP 47-7319 (JP, Y1) JP 46-24170 (JP , Y1) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01L 13/08 F02N 17/00

Claims (28)

(57) [Claims] A camshaft having a plurality of cam lobes;
A plurality of combustion chambers of an engine having a first valve actuator engagable with a first cam lobe associated with a first combustion chamber and a second valve actuator engagable with a second cam lobe associated with a second combustion chamber. A compression release device for reducing compression within a single lift member engagable with both the first and second valve actuators; and determining the position of the single lift member with engine speed. And a centrifugal force responsive means for changing the compression force according to the following. 2. The single lift member is engagable with said single lift member.
The apparatus of claim 1, further comprising a single shaft operable by the centrifugal force responsive means to change the position of the single lift member in response to engine speed. 3. The single shaft extends substantially through at least one of the cam lobes, and the single lift member is disposed substantially between the two cam lobes. The compression force releasing device according to claim 2. 4. The compression force releasing device according to claim 1, wherein said centrifugal force response means includes a flyweight. 5. The single lift member is engagable with said single lift member.
Further comprising a single shaft operable by the centrifugal force responsive means to change the position of the single lift member in response to engine speed, the single shaft being integral with the flyweight. The compression force releasing device according to claim 4, wherein the compression force releasing device is formed integrally. 6. The apparatus of claim 1, wherein said single lift member is adapted to be disposed substantially adjacent to an outer surface of said camshaft. 7. The apparatus of claim 1, wherein said single lift member is at least partially received within a guideway of said camshaft. 8. The single lift member has a first prong and a second prong, the first prong engaging a first guideway of the camshaft for engaging one of the valve actuators. The camshaft of claim 1, wherein the second prong is movably received therein and the second prong is partially received within a second guideway of the camshaft for engaging a second valve actuator. Compression force release device. 9. The first and second valve actuating devices are located at two different angular positions which are distinctly different with respect to a longitudinal axis of the camshaft, and wherein the single lift member comprises: A first engageable with the first valve actuator;
The compression release device of claim 1, comprising a portion and a second portion engagable with the second valve actuator. 10. An engine in a plurality of combustion chambers of an engine having a camshaft with a plurality of cam lobes and a plurality of valve actuators, each of which is associated with one of the plurality of combustion chambers. A compression force release device for reducing the compression force of: a plurality of lift members each engageable with at least one valve actuating device; and the camshaft substantially engageable with the plurality of lift members. A single shaft positioned outwardly and centrifugal force responsive means for actuating the single shaft to vary the position of each of the plurality of lift members in response to engine speed. Characteristic compression release device. 11. The compression force releasing device according to claim 10, wherein said centrifugal force response means includes a flyweight. 12. The compression force releasing device according to claim 11, wherein said single shaft is formed integrally with said fly weight in one piece. 13. The engine having a first valve actuator and a second valve actuator located at two distinct angular positions with respect to a longitudinal axis of the camshaft, wherein the plurality of lifts are provided. 11. The compression releasing device according to claim 10, wherein the member includes a first lift member engageable with the first valve actuator and a second lift member engageable with the second valve actuator. 14. The apparatus of claim 10, wherein at least one of said plurality of lift members is adapted to be disposed substantially adjacent to an outer surface of said camshaft. 15. The device of claim 10, wherein at least one of the plurality of lift members has an elongated portion at least partially received within a guideway of the camshaft. 16. The apparatus according to claim 10, wherein at least one of said plurality of lift members forms a portion of said cam lobe and is movable relative to said cam lobe for engaging a valve actuator. The compression force release device according to claim 1. 17. The cam lobe is formed from at least two laminates attached to the camshaft, the at least one lift member is formed from one of the two laminates, 17. The device of claim 16, wherein the at least one lift member is movable with respect to the other stack for engaging a valve actuator. 18. The apparatus of claim 10, wherein said plurality of lift members include at least one lift member engageable with two valve actuators. 19. The device of claim 10, wherein said single shaft extends substantially through at least one of said cam lobes. 20. At least one of said plurality of lift members is disposed substantially between two cam lobes.
20. The compression force releasing device according to claim 19. 21. A plurality of combustion chambers of an engine having a camshaft with a plurality of cam lobes and at least two valve actuators, each of which is associated with one of the plurality of combustion chambers. A lift member capable of engaging with the two valve actuators, a fly weight, and changing a position of the lift member according to an engine speed. A single shaft positioned substantially outside the camshaft, the single shaft being actuated by the flyweight. 22. The device of claim 21, wherein said at least one lift member is engagable with two valve actuators and has a shape substantially conforming to an outer surface of said camshaft. . 23. The apparatus of claim 22, wherein the at least one lift member includes a first prong for engaging a first valve actuator and a second prong for engaging a second valve actuator. A compressive force release device as described in any of the preceding claims. 24. Each of said first and second prongs comprises:
24. The compression release device of claim 23, wherein the compression release device is at least partially received in a guideway of the camshaft. 25. The camshaft having a plurality of guideways, wherein the at least one lift member is engagable with a first valve actuator and is partially within the first guideway of the camshaft. Having a received elongated portion, the device further comprises a second lift member engagable with a second valve actuation device, the second lift member comprising a second lift member of the camshaft.
22. The compression release device of claim 21, having an elongated portion at least partially received in the guideway. 26. The camshaft includes a cam lobe formed from at least two laminates attached to the camshaft, and the at least one lift member is formed from one of the two laminates. 22. The compression release device of claim 21, wherein the at least one lift member is movable relative to the other stack to engage a valve actuator. 27. The single shaft extends substantially through at least one of the cam lobes and the at least one lift member is disposed substantially between two of the cam lobes. 22. The compression force releasing device according to claim 21, wherein: 28. A camshaft having a plurality of cam lobes, a first valve actuator engagable with a first cam lobe associated with a first combustion chamber, and engagable with a second cam lobe associated with a second combustion chamber. A compression release device for reducing compression forces in a plurality of combustion chambers of an engine having a second valve actuation device, wherein the first and second valve actuation devices are integrally formed as one piece. A compression release device comprising: a single engageable lift member; and a centrifugal force responsive means for changing a position of the single lift member according to engine speed.