JPH04117111U - Variable valve timing lift device - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the contact surface pressure of the engagement portion between the switching pin 16 and the shaft 12 of the roller follower 13, thereby reducing wear and damage to the engagement portion. [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 slot plate 17b of the cap 17 serves as a rotation restriction mechanism that prevents the switching pin 16 from rotating so that it can advance or retreat.
The switching pin 16 is provided with a slit 16d that engages with the shaft 12 of the roller follower 13 in its advanced state.
The switching pin 16 is provided with a cut surface 16 that makes line contact with the circumferential surface.

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 stability of combustion. Therefore, conventionally, narrow opening angle and low A rocker arm for low speeds that contacts the low speed cam of the lift, and a rocker arm for high speeds with a wide opening angle and high lift. Equipped with a high-speed rocker arm that comes into contact with the cam, it is suitable for use in the low and medium speed range of the engine. The low-speed cam drives the intake and exhaust valves via the low-speed rocker arm, and the engine In the high speed rotation range of the engine, the high speed rocker arm and low speed rocker arm are integrated. Suction and exhaust are carried out by the high-speed cam through the high-speed rocker arm and the low-speed rocker arm. A variable valve timing lift device configured to drive a gas valve is known. There is.

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. This switching pin is advanced to integrate the high-speed rocker arm and low-speed rocker arm. The applicant has already proposed a variable valve timing type valve train configured to (See Japanese Patent Application No. 1-306078). Here, the shaft of the roller follower A ring-shaped engagement groove is formed in the groove, and the switching pin extends into this engagement groove and engages. The high-speed rocker arm and low-speed rocker arm are integrated. .

0004

[Problem that the idea aims to solve]

By the way, the variable valve timing type actuator described in the above-mentioned Japanese Patent Application No. 1-306078 In the valve device, the radius of curvature of the engagement groove is set to be larger than the radius of curvature of the engagement pin. Otherwise, the switching pin will not be able to advance smoothly into the engagement groove. But then, the engagement Since the groove is ring-shaped, the engaging part with the switching pin becomes a point contact, and the contact surface pressure of the engaging part is reduced. This increases the risk of wear and damage to the engaging portion.

[0005] Therefore, the present invention aims to reduce the contact surface pressure of the engagement part between the switching pin and the shaft of the roller follower. The purpose is to reduce wear and damage of the engaging part by reducing the amount of friction.

[0006]

[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 rotation restriction mechanism that prevents the switching pin from rotating so that it can move forward and backward. In addition, the switching pin is provided with a shaft circumference of the roller follower in its extended state. The method is to provide a cut surface that makes line contact with the surface.

[0007]

[Effect]

By adopting this method, the switching pin is prevented from rotating due to the rotation restriction mechanism. When the roller follower moves forward and backward, the cut surface lines up with the circumferential surface of the shaft of the roller follower. Contact. Therefore, the engagement between the switching pin and the shaft of the roller follower as in the past The contact surface pressure of the engaging part is significantly reduced compared to the case where the parts make point contact, reducing wear and tear on the engaging part. Damage is reduced.

[0008] In addition, compared to the conventional structure, we have added a cut surface to the switching pin, making it easier to rotate the switching pin. The structure is simple because only a regulating mechanism is required.

[0009]

【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.

0010 On the other hand, reference numeral 9 has one end rotatably supported by the rocker shaft 10 and the other end. A pair of swing types that abut the end of the valve stem 1a via an adjustment screw 11. It is a rocker arm for low speeds, and is mounted in the axial direction of the camshaft 4 in correspondence with the intake valve 1. are arranged in parallel. And the longitudinal intermediate portion of these pair of low-speed rocker arms 9 In each case, a roller follower 13 rotates via a shaft 12 that connects the two. freely supported.

[0011] 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 narrow opening angle and low lift camshafts arranged in the camshaft 4 for low speed Each is in contact with the cam 4a. As the camshaft 4 rotates, a pair of low The speed cam 4a swings a pair of low speed rocker arms 9 via each roller follower 13. By moving, the pair of intake valves 1 open and close the intake port 3 with a narrow opening angle and low lift. It looks like this.

0012 Here, between the pair of low-speed rocker arms 9, the rocker shaft 10 A swing-type high-speed rocker arm 14 rotatably supported is arranged. . This high-speed rocker arm 14 is connected to the shaft 12 of the roller follower 13. It has a protrusion 14a that protrudes between the shaft 4 and the protrusion 14a. , there is a spring in contact with a high-speed cam 4b with a wide opening angle and high lift formed on the camshaft 4. A ripper 14b is formed. In addition, this high-speed rocker arm 14 has the above-mentioned system. A protrusion 14c that bypasses the shaft 12 and protrudes toward the cylinder head 2 is formed. Ru. In response to this, the cylinder head 2 has a built-in spring that allows it to protrude. A holding device 15 having a plunger 15a is fixed. and The projection 14c comes into contact with the plunger 15a of the elastic holding device 15 and is pressed. Therefore, the slipper 14b of the high-speed rocker arm 14 is always in pressure contact with the high-speed cam 4b. , constantly swings without interfering with the shaft 12 due to the rotation of the camshaft 4. It has become so.

[0013] 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.

[0014] 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.

[0015] 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 As shown in FIG. 6, the outer end has a slot groove 17a, and the inner end has a slot plate 17b. A strut provided on the high-speed rocker arm 14 passes through the accommodation hole 14e. By fitting the pin 18 into the slot groove 17a, it is prevented from coming out from the accommodation hole 14e, and Rotation is stopped. Then, the slit plate 17b is inserted into the slit 16d of the switching pin 16. When fitted together, a rotation regulating mechanism is configured, and the cut surface 16c of the switching pin 16 is rotated. The switching pin 16 is housed so as to face parallel to the circumferential surface of the shaft 12 of the rough follower 13. It is prevented from rotating so that it can move forward and backward with respect to the hole 14e.

[0016] 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 is filled with oil from the rocker shaft 10 so as to be pushed out to the side. An oil hole 14g is formed that communicates the passage 10a and the accommodation hole 14e. Here above The oil passage 10a is connected to a hydraulic circuit having an electromagnetic switching type three-way valve (not shown). In addition, the electromagnetic switching type three-way valve has a switching point of, for example, an engine rotation speed of 5000 rpm. Above that, pressure oil is supplied to the oil passage 10a, and below that, pressure oil is supplied to the oil passage 10a. It is designed to drain pressure oil.

[0017] Here, the base circle of the high-speed cam 4b that the slipper 14b contacts is as follows: It is formed smaller than the base circle of the low speed cam 4a, and the difference in radius is due to the cut. When the replacement pin 16 is pushed out, its cut surface 16c touches the shaft of the roller follower 13. The shaft extends along the tangential direction to the shaft 12, and a predetermined clip is applied to the circumferential surface of the shaft 12. A predetermined dimensional difference is set to allow smooth line contact with clearance. Ru. Then, the protruding position of the pin body 16a having this cut surface 16c is set at a predetermined position. A pin body 16 is attached to the protrusion 14a of the high-speed rocker arm 14 so as to regulate the A stopper pin 20 facing the advancing path of the tip a is suspended horizontally.

[0018] 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, it is biased by the return spring 19. As shown in FIG. 1, the switching pin 16 has its pin body 16a inserted into the fitting hole 14d. It is in a drawn-in state of withdrawal. Then, the slipper 14b comes into contact with the high-speed cam 4b. The high-speed rocker arm 14 engaged with the shaft 12 of the roller follower 13 It swings without any effort. Therefore, the low speed rocker arm 9 is The follower 13 contacts the low-speed cam 4a with a narrow opening angle and low lift, and the rocker shaft 10 It swings around and opens and closes the intake valve 1 with a narrow opening angle and low lift.

[0019] 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 along the tangential direction of the shaft 12 and cuts the shaft 12. ride on top. Then, the tip surface of the pin body 16a abuts against the stopper pin 20. The switching pin 16 stops at this position, and the cut surface 16c is in line contact with the circumferential surface of the shaft 12. (See Figure 5). Therefore, the high-speed rocker arm 14 is attached to the roller follower 13. Engages with the shaft 12 to forcibly rotate the low speed rocker arm 9 around the rocker shaft 10. It starts to sway. Therefore, the low speed rocker arm 9 is a roller follower. 13 is separated from the low-speed cam 4a, and the suction is performed according to the rotation of the high-speed cam 4b. The air valve 1 is opened and closed with a wide opening angle and a high lift.

[0020] Note that when the engine speed drops below 5000 rpm again, the hydraulic circuit power is turned off. 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. .

[0021] In this way, when the engine speed is 5000 rpm or more, the intake valve 1 is opened at a wide opening angle and high. When opening and closing with a lift, the cut surface 16c of the switching pin 16 is connected to the shaft of the roller follower 13. By engaging in line contact with the circumferential surface of the shaft 12, the high-speed rocker arm 14 can be used for low-speed use. It engages the rocker arm 9, and unlike the conventional case, the switching pin and roller follower are connected to each other. The contact surface pressure of the engaging part is significantly reduced compared to those that engage by point contact with the shaft. Ru. Therefore, wear and damage to the engaging portion can be reduced.

[0022] Furthermore, in this embodiment, the low-speed rocker arm 9 tends to run out of oil film at low speeds. Because it contacts the low speed cam 4a through the roller follower 13 instead of the slipper. , the driving torque is reduced and the fuel efficiency of the engine is improved.

[0023]

[Effect of the idea]

As explained above, according to the present invention, the switching pin is prevented from rotating by the rotation regulating mechanism. The cut surface is in direct contact with the circumferential surface of the shaft of the roller follower in the advanced state. touch Therefore, unlike the conventional method, the engagement part between the switching pin and the shaft of the roller follower is The contact surface pressure of the engaging part is significantly reduced compared to the point contact of the engaging part. wear and damage can be reduced.

[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 an enlarged sectional view of essential parts of one embodiment.

FIG. 6 is a perspective view of a cap 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 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 Accommodating square hole 10 Rocker shaft 10a Oil passage 11 Adjustment screw 12 Shaft 13 Roller follower 14 High-speed rocker arm 14a Projection, 14b Slipper, 14c Projection, 1
4d fitting hole, 14e accommodation hole, 14f stage, 14g oil hole 15 retention 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

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 variable valve characterized in that a rotation regulating mechanism is provided for preventing rotation of the switching pin so that the switching pin can move forward and backward, and the switching pin is provided with a cut surface that makes line contact with the circumferential surface of the shaft of the roller follower in the extended state. Timing lift device.