JPH04117121U - Variable valve timing lift device - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to reduce the noise of the valve system from the low speed range to the high speed range of the engine, to smoothly engage and disengage the high speed rocker arm and the low speed rocker arm, and to avoid overlapping the intake and exhaust valves. be managed appropriately. [Structure] Variable valve timing that engages and disengages the switching pin 16 and the shaft 12 of the roller follower 13 by moving the switching pin 16 back and forth to switch between driving the valve 1 by the high-speed cam 4b and driving the valve 1 by the low-speed cam 4a. In the lift device, the hydraulic lash adjuster 11 absorbs the valve clearance on the low-speed rocker arm 9 side, and the large cam ramp of the high-speed cam 4b prevents the high-speed rocker arm 14 from bouncing. Further, a predetermined clearance is provided between the switching pin 16 and the shaft 12 to facilitate the forward and backward movement of the switching pin.
Furthermore, the cam ramp of the low-speed cam 4a is set small to appropriately manage the overlap of the intake and exhaust valves.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is a valve train system that opens and closes intake and exhaust valves in vehicle engines, etc. The low-speed cam drives the valves to open and close depending on the engine operating conditions. Variable valve timing lift device that switches between opening and closing the valve using a high-speed cam. Regarding the location.

0002

[Conventional technology]

In vehicle engines, etc., the opening angle and lift of the intake and exhaust valves depend on the engine. It is preferable to set it according to the engine speed, and generally in the low and medium speed range of the engine. It is best to set the engine to a narrow opening angle and low lift, and set it to a wide opening angle and high lift in the high speed rotation range. This is preferable in terms of improving the filling efficiency and combustion stability of the fuel. Therefore, in the past, narrow opening angle and low A low-speed rocker arm that contacts the low-speed cam of the foot, and a high-speed cam with a wide opening angle and high lift. It is equipped with a high-speed rocker arm that comes into contact with the engine. The high-speed cam drives the intake and exhaust valves via the low-speed rocker arm, and the engine In the high-speed rotation range, the high-speed rocker arm and low-speed rocker arm are integrated. Intake and exhaust via the high-speed rocker arm and low-speed rocker arm by the high-speed cam A variable valve timing lift device configured to drive a valve is known. Ru.

0003 In this basic configuration, the low-speed rocker arm contacts the low-speed cam. In addition to providing a roller follower that A switching pin that moves forward and backward is installed on the high-speed rocker arm. Advance this switching pin to engage the shaft above, and connect the high-speed rocker arm and low-speed rocker arm. Variable valve timing type valve train configured to integrate with speed rocker arm The applicant has already proposed a new system (see Japanese Patent Application No. 1-306078).

0004

[Problem that the idea aims to solve] By the way, the cam drives the engine that opens and closes the intake and exhaust valves via the rocker arm. In engines, valve clear runs may occur due to changes in engine temperature or changes over time. changes occur in the valve train, causing noise in the valve train and causing bounce. . Hydraulic lash adjustment that automatically adjusts valve clearance A caster is installed between the rocker arm and the valve, and the valve is driven through this. By doing this, you can reduce the noise of the valve train and prevent the occurrence of bounce. be able to. In addition, regarding valve clearance, it is maintenance free. You can also.

[0005] However, the variable valve timing type actuator described in the above-mentioned Japanese Patent Application No. 1-306078 In a valve device, the switching pin moves in a direction that crosses the shaft of the roller follower. By retracting, the engagement and release of the two is performed, and this switching operation is performed in a circular manner. In order to do this smoothly, it is necessary to provide a predetermined clearance between the two. but With this kind of clearance, the hydraulic lash adjuster In a valve system, if the cam ramp is made as small as possible, the high-speed cam will The engine that opens and closes the intake and exhaust valves via the rocker arm and low-speed rocker arm. In the high engine rotation range, the clearance exceeds the cam ramp height, resulting in high The speed rocker arm bounces, causing a lot of noise in the valve train.

[0006] Therefore, the present invention was designed to allow the switching pin to move smoothly forward and backward, while still allowing the engine to Valve train noise can be reduced from low to high rotation speeds, and the intake and exhaust Variable valve timing adjustment that can properly manage valve overlap The purpose is to provide a lift device.

[0007]

[Means to solve the problem]

For this purpose, the present invention is designed for high-speed use with a wide opening angle and high lift formed on the camshaft. High speed that constantly swings around the rocker shaft by contacting the cam through the slipper rocker arm and a low-speed cam with narrow opening angle and low lift formed on the camshaft. By making contact through the rocker follower, it swings around the rocker shaft and drives the valve. It is built into the moving low-speed rocker arm and the above-mentioned high-speed rocker arm so that it can move forward and backward. As it advances, it engages with the shaft of the roller follower and activates the low-speed rocker arm. It swings together with the high-speed rocker arm, and its retraction allows the low-speed rocker arm to move. It is equipped with a switching pin that swings independently, and when this switching pin is retracted or retracted, the low speed cam The valve is driven by the swing of the low-speed rocker arm, and in the advanced state, the high-speed cam drives the valve. A variable valve timer configured to drive the valve by the rocker arm for low speeds. In the engine lift device, a hydraulic fluid is installed between the low-speed rocker arm and the valve. Set the cam ramp of the low-speed cam to a smaller value by using a lock lash adjuster. In addition, the cam ramp of the high-speed cam above prevents the high-speed rocker arm from bouncing. Set it so that the specified distance between the switching pin and the shaft of the roller follower is This is done by providing clearance.

[0008]

[Effect]

By adopting this method, the low-speed cam can be moved via the low-speed rocker arm. In the low engine speed range where the valves are opened and closed by The valve adjuster adjusts the valve clearance of the valve train from the low-speed cam to the valve. The high-speed cam is connected to the valve via the high-speed rocker arm and the low-speed rocker arm. In the high-speed range of the engine that drives the engine to open and close the The caster absorbs the valve clearance of the valve train from the low-speed rocker arm to the valve. regarding the clearance that occurs between the high-speed rocker arm and the low-speed rocker arm. The large cam ramp on the high-speed cam prevents the high-speed rocker arm from bouncing. do. As a result, noise from the valve train increases from the low engine speed range to the high engine speed range. reduced.

[0009] Here, maintain a specified clearance between the switching pin and the shaft of the roller follower. Because of this, the switching pin can move smoothly forward and backward to connect the high-speed rocker arm and the low-speed rocker arm. To smoothly engage and disengage the arm.

0010 In addition, the cam ramp of the low-speed cam was set small, so the intake and exhaust valves were The burlap can be managed appropriately, reducing combustion during low loads such as idling. Stabilize. Also, maintenance is free regarding valve clearance.

[0011]

【Example】

Hereinafter, one embodiment of the present invention will be described in detail based on the accompanying drawings. Figures 1 and 2 show a 4-valve engine that includes a variable valve timing lift device. Of the engine valve train, for example, the intake valve side is shown, and the exhaust valve side is almost the same. It is configured. Therefore, let us explain the intake valve side as a representative of these. The middle code 1 opens and closes two intake ports 3 formed in the cylinder head 2. The camshaft 4 is a pair of intake valves arranged in parallel in the axial direction of the camshaft 4. and The pair of intake valves 1 are attached to a valve stem 1a via a cotter 5. The ring retainer 6 is biased by the valve spring 7, so that the valve body 1b is They sit on valve seats 8 and close the intake ports 3, respectively.

0012 Here, the cylinder head 2 has a guide hole 2 where the end of the valve stem 1a faces. a is formed, and this guide hole 2a communicates with the oil passage 2b of the cylinder head 2. The bucket-shaped hydraulic lash adjuster 11 is slidably fitted. are doing.

[0013] On the other hand, the reference numeral 9 has its base end rotatably supported by the rocker shaft 10, and its distal end The formed nose 9b is inserted through the hydraulic lash adjuster 11. A pair of swing-type low-speed rocker arms that come into contact with the valve stem 1a. They are arranged in parallel in the axial direction of the camshaft 4 in correspondence with the air valves 1. and these A shaft 1 connecting the pair of low-speed rocker arms 9 in the longitudinal direction middle part thereof A roller follower 13 is rotatably supported through each of the rollers 2 and 2.

[0014] FIG. 3 shows the low-speed rocker arm 9, in which each roller follower 13 is A rectangular housing hole 9a is formed in the low-speed rocker arm 9 so that a part of the outer periphery of the accommodating hole 9a is exposed. a pair of low-speed cams 4a formed on the camshaft 4, respectively. are in contact with each other. As the camshaft 4 rotates, the pair of low-speed cams 4a each rotate. By swinging a pair of low-speed rocker arms 9 via roller followers 13, one The paired intake valve 1 opens and closes the intake port 3, and the valve clearance at that time is high. Dorolic Lash Adjuster 11 is designed to absorb it.

[0015] Further, between the pair of low-speed rocker arms 9, the rocker shaft 10 is connected to the rocker shaft 10. A swing-type high-speed rocker arm 14 that is rotatably supported is arranged. This high-speed rocker arm 14 is connected to the shaft 12 of the roller follower 13 and the cam. It has a protrusion 14a that protrudes between the shaft 4 and the protrusion 14a. A slipper 14b is formed that contacts the high-speed cam 4b formed on the camshaft 4. has been done. In addition, this high-speed rocker arm 14 is provided with a bypass around the shaft 12. A protrusion 14c that protrudes toward the cylinder head 2 is formed. In response to this The cylinder head 2 has a plan that has a protruding habit due to a built-in spring. A holding device 15 having a jaw 15a is fixed. And this bullet holding device 15 When the protrusion 14c comes into contact with the plunger 15a and is pressed, the high-speed rocker The arm 14 has a slipper 14b that is always in pressure contact with the high-speed cam 4b, and the camshaft 4 Due to rotation, it is designed to constantly swing without interfering with the shaft 12. .

[0016] In such a high-speed rocker arm 14, the rocking motion is transferred to the low-speed rocker arm 9. Two switching pins 16 for transmission are built in parallel. This switching pin 1 6 has a collar 16b at one end of the pin body 16a, and a collar 16b at the other end, as shown in FIG. A cut surface 16c parallel to the axis is formed on the circumferential surface up to the tip, and the above-mentioned collar 16b A slit 16d is formed in the axial direction from the side, and a slit 16d is formed through the slit 16d. An oil hole 16e is formed on the circumferential surface.

[0017] On the other hand, the two switching pins 16 are connected parallel to each other on the high-speed rocker arm 14. Two through-holes are formed to accommodate the device so that it can move forward and backward in the state. These penetrations As shown in FIG. 5, the pin body 16a of the switching pin 16 is slidably fitted into the hole. A fitting hole 14d and a housing hole 14 that movably accommodate the collar 16b of the switching pin 16. e is continuous through the step 14f and does not interfere with the rocker shaft 10. The position is perpendicular to this. The opening side end of the fitting hole 14d is The side facing the foot 12 is a semicircular hole that is open, and the slipper 14b and the shaft are connected to each other. It is coming between 12 and 12.

[0018] Here, the pin body 16a is fitted into the fitting hole 14d, and the collar 16 is fitted into the accommodation hole 14e. The switching pin 16 into which b is inserted is a cap that fits into the open end of the accommodation hole 14e. The collar 16b comes into contact with the collar 17 to prevent it from coming off. This cap 17 is It has a slot groove 17a at the outer end and a slot plate 17b at the inner end. A stopper pin 18 provided on the high-speed rocker arm 14 passes through the hole 14e. By fitting into the groove 17a, it is prevented from coming out from the accommodation hole 14e and also prevented from rotating. There is. Then, the slit plate 17b fits into the slit 16d of the switching pin 16, so that the rotation occurs. A motion restriction mechanism is configured, and the cut surface 16c of the switching pin 16 is aligned with the roller follower 13. The switching pin 16 is advanced into the accommodation hole 14e so as to face the circumferential surface of the shaft 12 in parallel. Rotation is stopped so that it can be retracted.

[0019] Also, the step 14f between the fitting hole 14d and the accommodation hole 14e and the connecting pin 16 are connected to each other. A return spring 19 is interposed between the switching pin 16 and the switching pin 16. The body 16a is pulled into the fitting hole 14d. And this switching pin 1 6 of the pin body 16a against the return spring 19 at the open end of the fitting hole 14d. The high-speed rocker arm 14 has a portion inside the rocker shaft 10 so as to push it out to the side. An oil passage 14g is formed that communicates the oil passage 10a and the accommodation hole 14e. Ru. Here, the oil passage 10a has an electromagnetic switching type three-way valve (not shown). The electromagnetic switching type three-way valve is connected to the pressure circuit, and the electromagnetic switching type three-way valve is 000 rpm is the switching point, and above that point, pressure oil is supplied to the oil passage 10a. , below which the pressure oil in the oil passage 10a is drained.

[0020] Here, as shown in the cam lift curve of FIG. 6, the low speed cam 4a has a narrow opening angle and a low lift curve. The cam ramp on the opening side is approximately 0.03 mm within 5 degrees. The cam lamp on the closing side has a hydraulic lash adjuster. Considering the collapse of the star 11, the angle is set to about 0.15 mm at 10 degrees. on the other hand , the high-speed cam 4b has a wide opening angle and high lift profile, and the cam ramp on the opening side is 30°. The cam ramp on the closing side is set to about 0.35 mm at 40°. m, and this large cam ramp is used to control the high-speed rocker arm 14. This is designed to prevent bounces.

[0021] Also, the base circle of the high speed cam 4b is the same as the base circle of the low speed cam 4a. The difference in radius is that the switching pin 16 is smaller than the roller follower 13. It is pushed out to the shaft 12 side and the cut surface 16c is tangential to the shaft 12. A predetermined dimensional difference that allows for smooth advance with a predetermined clearance when advancing. is set to . The advancing position of the pin body 16a having this cut surface 16c The protrusion 14a of the high-speed rocker arm 14 is provided with a A stopper pin 20 is horizontally suspended facing the advancing path of the tip of the pin body 16a.

[0022] Next, the operation of one embodiment configured as described above will be explained. When the engine speed is 5000 rpm or less, the electromagnetic three-way valve in the hydraulic circuit Since the pressure oil in the oil passage 10a is drained, the return spring 19 is biased. The receiving switching pin 16 has its pin body 16a inserted into the fitting hole 1 as shown in FIG. It is in a retracted state drawn into 4d. Therefore, the slipper 14b is connected to the high-speed cam 4b. The high-speed rocker arm 14 that is in contact with the shaft 12 of the roller follower 13 It swings in an idle state without engaging with. For this reason, the low speed rocker arm 9 The roller follower 13 contacts the low-speed cam 4a with a narrow opening angle and low lift, and the rocker shaft The intake valve 1 is opened and closed with a narrow opening angle and a low lift.

[0023] When the engine speed exceeds 5000 rpm, the electromagnetic three-way valve in the hydraulic circuit is adapted to supply pressure oil to the accommodation hole 14e via the oil passage 10a and the oil hole 14g. Ru. Therefore, hydraulic pressure is created in the switching pin 16 to overcome the bias of the return spring 19. The switching pin 16 has its pin body 16a facing the open end side of the fitting hole 14d. and advance into the country. As shown in FIG. 7, as the camshaft 4 rotates, the slipper 14b comes into contact with the base circle portion of the high-speed cam 4b, the switching pin The cut surface 16c of No. 16 advances smoothly along the tangential direction of the shaft 12 to form the shaft. Climb onto shaft 12. The tip end surface of the pin body 16a is the stopper pin 20. The switching pin 16 stops at the position where it contacts the shaft 12, and the cut surface 16c is in contact with the shaft 12. It engages in line contact with the peripheral surface (see Fig. 5). Therefore, the high-speed rocker arm 14 is engages with the shaft 12 of the roller follower 13 and forcibly locks the low-speed rocker arm 9. It will now swing around the rocker shaft 10. For this reason, the rocker arm for low speed 9, the roller follower 13 is separated from the low-speed cam 4a, and the high-speed cam 4 The intake valve 1 is opened and closed with a wide opening angle and a high lift in accordance with the rotation of the valve b.

[0024] Also, if the engine speed drops below 5000 rpm again, the hydraulic circuit will Since the magnetic switching type three-way valve drains the pressure oil in the oil passage 10a, the switching pin 16 is The pin body 16a is pulled into the fitting hole 14d by the bias of the spring spring 19, The high-speed rocker arm 14 is connected to the shaft 12 of the roller follower 13 as described above. The intake valve 1 opens and closes with a narrow opening angle and low lift. .

[0025] Here, there is a hide between the low speed rocker arm 9 and the intake valve 1 as described above. Since the Rorik Lash Adjuster 11 is installed, the engine speed can be adjusted. In the area below 5000 rpm, this hydraulic lash adjuster 11 absorbs the valve clearance of the valve train from the low speed cam 4a to the intake valve 1. Ru. In addition, even when the engine speed is over 5000 rpm, the hydraulic ・The movement of the lash adjuster 11 from the low-speed rocker arm 9 to the intake valve 1 It absorbs the valve clearance of the valve system, and the high-speed rocker arm 14 and low-speed rocker arm The clearance between the high speed cams 9 is absorbed by the large cam ramp of the high speed cam 4b. To prevent the speed rocker arm 14 from bouncing. Therefore, the engine is in the low rotation range. The noise of the valve train is reduced over the high rotation range.

[0026] In particular, the roller follower 13 of the low-speed rocker arm 9 is connected to the low-speed cam 4a. The slipper 14b of the high-speed rocker arm 14 contacts the base circle, and the slipper 14b of the high-speed rocker arm 14 contacts the base circle. The cut surface 16 of the switching pin 16 is in contact with the base circle of the pin 4b. A predetermined clearance is provided between c and the circumferential surface of the shaft 12 of the roller follower 13. Therefore, the forward and backward movement of the switching pin 16 is smooth, and the high-speed rocker arm 1 4 and the low-speed rocker arm 9 are smoothly engaged and disengaged.

[0027] In addition, the hydraulic lash adjuster 11 takes air from the low-speed cam 4a. Since it absorbs the valve clearance of the valve train leading to valve 1, low-speed cam 4 The cam lamp of a can be set very small as mentioned above, and the intake and exhaust valves overlap can be appropriately managed.

[0028] In addition, in this embodiment, the hydraulic lash adjuster 11 is Fits slidably into the guide hole 2a of the cylinder head 2 having the oil passage 2b. Since it is a bucket type, it is difficult to increase the weight of the low-speed rocker arm 9 or increase the weight of the rocker arm 9. There is no formalization.

[0029] Also, the oil passage 2b to the hydraulic lash adjuster 11 is Oil passage 10a in rocker shaft 10 for advancing and driving switching pin 16 Since the hydraulic lash adjuster 11 is separated from the be able to exercise control independently and appropriately.

[0030] Furthermore, in this embodiment, high speed operation is performed in the region where the engine speed is 5000 rpm or more. The low-speed rocker arm 14 is engaged with the low-speed rocker arm 9 to open the intake valve 1 at a wide opening angle. When opening and closing with a lift, the cut surface 16c of the switching pin 16 is connected to the roller follower 13. Since it engages in line contact with the circumferential surface of the shaft 12, the contact surface pressure of the engaging part is a point contact. This is significantly reduced compared to the case where the wear and damage of the engaging portion is reduced.

[0031] In addition, the rocker arm 9 for low speeds is not a slipper that tends to run out of oil film, but a roller. Since it contacts the low speed cam 4a via the follower 13, its driving torque decreases. , improves engine fuel efficiency, etc.

[0032]

[Effect of the idea]

As explained above, according to the present invention, the low speed cam is connected via the low speed rocker arm. Hydraulic lash occurs in the low engine speed range where the valves are opened and closed. ・The adjuster absorbs the valve clearance of the valve train from the low-speed cam to the valve. The high-speed cam connects the valve via the high-speed rocker arm and the low-speed rocker arm. Hydraulic lash adjustment is used in the high speed range of engines that drive opening and closing. The star absorbs the valve clearance of the valve train from the low-speed rocker arm to the valve. However, the clearance between the high-speed rocker arm and the low-speed rocker arm is the same as the high-speed rocker arm. The large cam ramp absorbs this and prevents the high-speed rocker arm from bouncing. child This reduces valve system noise from low to high engine speeds. be able to.

[0033] Here, maintain a specified clearance between the switching pin and the shaft of the roller follower. This allows the switching pin to move forward and backward smoothly to connect the high-speed rocker arm and the low-speed rocker arm. It is possible to smoothly engage and disengage the car arm.

[0034] In addition, the cam ramp of the low-speed cam is set small, so the intake and exhaust valve overflow Able to properly manage wraps.

[Brief explanation of drawings]

FIG. 1 is a sectional side view of an engine valve train system to which an embodiment of the present invention is applied.

FIG. 2 is a front perspective view showing the arrangement of an engine valve train to which an embodiment is applied.

FIG. 3 is a perspective view of a low-speed rocker arm in one embodiment.

FIG. 4 is a perspective view of a switching pin in one embodiment.

FIG. 5 is a cross-sectional view of the high-speed rocker arm for explaining the advancing operation of the switching pin in one embodiment.

FIG. 6 is a diagram showing cam lift curves of a low-speed cam and a high-speed cam in one embodiment.

FIG. 7 is a side sectional view corresponding to FIG. 1 illustrating the operation of one embodiment.

[Explanation of symbols]

1 Intake valve 1a Valve stem, 1b Valve body 2 Cylinder head 2a Guide hole, 2b Oil passage 3 Intake port 4 Camshaft 4a Low speed cam, 4b High speed cam 5 Cotter 6 Spring retainer 7 Valve spring 8 Valve seat 9 Low speed rocker arm 9a Accommodation square hole, 9b Nose 10 Rocker shaft 10a Oil passage 11 Hydraulic lash adjuster 12 Shaft 13 Roller follower 14 High speed rocker arm 14a Projection, 14b Slipper, 14c Projection, 1
4d Fitting hole, 14e Accommodation hole, 14f Step, 14g
Oil passage 15 Retaining device 15a Plunger 16 Switching pin 16a Pin body, 16b Collar, 16c Cut surface,
16d slit, 16e oil hole 17 cap 17a slit groove, 17b slit plate 18 stopper pin 19 return spring 20 stopper pin

──────────────────────────────────────────────── ─── Continued from front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location F02B 77/00 N 7049-3G

Claims (1)

[Scope of utility model registration request] 1. A high-speed rocker arm that constantly swings around a rocker shaft by contacting a high-speed cam with a wide opening angle and high lift formed on a camshaft via a slipper;
The low-speed rocker arm swings around the rocker shaft and drives the valve by contacting the low-speed cam with a narrow opening angle and low lift formed on the camshaft via a roller follower, and the high-speed rocker arm can move forward and backward. It is equipped with a built-in switching pin that engages the shaft of the roller follower when the pin moves forward, causing the low-speed rocker arm to swing integrally with the high-speed rocker arm, and when the pin moves back, the low-speed rocker arm independently swings. In a variable valve timing lift device configured such that when the switching pin is retracted, the valve is driven by the swinging of the low-speed rocker arm by the low-speed cam, and when the switching pin is in the extended state, the valve is driven by the swinging of the low-speed rocker arm by the high-speed cam. A hydraulic lash adjuster is interposed between the low-speed rocker arm and the valve to set the cam ramp of the low-speed cam small, and the cam ramp of the high-speed cam is designed to prevent the high-speed rocker arm from bouncing. A variable valve timing lift device characterized in that a predetermined clearance is provided between a switching pin and a shaft of a roller follower by setting the clearance large.