JPH0196406A - Engine valve drive device - Google Patents

Abstract

PURPOSE:To prevent inclination of each rocker arm reliably by supporting each rocker arm on a rocker shaft through an eccentric bush. CONSTITUTION:Low speed and high speed rocker arms 6, 11 to be driven through cam respective cams 13, 16 are provided, and an engaging/disengaging mechanism for coupling them separatably is provided between adjoining rocker arms 6, 11. An eccentric bush 10 is provided eccentrically to a rocker shaft 8 in order to support respective rocker arms 6, 11 slidably. A lash adjuster 24 contacts with HLA contact arm section 22 provided in the eccentric bush 10, and when the eccentric bush 10 is energized in one rotary direction, respective rocker arms 6, 11 are energized to the side of corresponding cams 13, 16. Consequently, inclination of respective rocker arms can be prevented reliably and open/close control of a valve 1 can be made accurately.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an engine valve in which the valve opening/closing timing and lift amount are variable according to the operating condition by selectively using a plurality of rocker arms. This relates to a drive device.

[Conventional technology]

Conventionally, in a vehicle engine, a low-speed rocker arm and a high-speed rocker arm are driven in parallel by a low-speed cam and a high-speed cam that is designed to open the valve for a longer period than the low-speed cam. The rocker arm for low speeds is connected to the intake or exhaust valve, and the locking arms on both ends are separably connected by a hydraulic plunger-type engagement/release mechanism, so that the locking arms on both ends can be separated at low engine speeds. By doing so, the valve is opened and closed by the low-speed cam, while when the engine is running at high speeds, the valve is opened and closed by the high-speed cam by connecting the two-end lever arm, thereby reducing the pulp opening period at high speeds. It has been proposed that the length is longer than that at low rotation speeds (see Japanese Utility Model Application No. 61-58605).

In this type of engine, for example, a high-speed rocker arm is supported by a shaft provided on a low-speed hook arm, and a hydrolink lash adjuster (hereinafter referred to as hereinafter referred to as a It is conceivable to support the rocker arm swingably by the HLA (abbreviated as A), and to urge each rocker arm toward each cam by the HLA.

[Problem that the invention seeks to solve]

However, according to the above structure, the contact position of the high-speed cam with respect to the high-speed rocker arm is axially shifted from the end pivot part of the low-speed rocker arm, which is the support part of the double-ended lock arm. The double-ended locking arm tilts in response to the pressing force of the high-speed cam against the high-speed rocker arm, and as a result, each cam comes into contact with each rocker arm only partially in the axial direction, so the valve There was a problem that opening/closing control could not be performed accurately.

[Means for solving problems]

In order to solve the above-mentioned problems, the engine valve drive device according to the present invention has a plurality of rocker arms, each driven by an individual cam, arranged in parallel, and can be separated between adjacent rocker arms. In an engine valve drive device provided with a locking/disengaging mechanism connected to a rocker shaft, a rocker shaft provided eccentrically to the rocker shaft,
An eccentric bushing that swingably supports each rocker arm, and a contact portion provided on this eccentric bushing,
The device is characterized in that it includes a lash adjuster that biases each rocker arm toward the corresponding cam by biasing the eccentric bushing in one rotational direction.

[For production]

According to the above configuration, each rocker arm is supported by the rocker shaft via the eccentric bushing.
Each rocker arm no longer tilts.

In addition, when a gap occurs between each rocker arm and the corresponding cam, the lash adjuster rotates the eccentric bushing in one of the rotation directions, so that each rocker arm rotates around the connection with the valve as a fulcrum. It is swung toward the cam, thereby absorbing the gap between each rocker arm and the corresponding cam.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 to 4.

Figure 1 shows only the valve drive mechanism on the intake side of a double overhead camshaft type multi-cylinder engine.
The above-mentioned engine includes two intake valves 1 per cylinder, and each intake valve 1 is slidably guided by a valve guide 2 to open and close an intake passage (not shown). Each intake valve 1 is biased in the A direction, that is, in the closing direction, by a valve spring 5 compressed between an upper seat 3 attached to the upper end of the intake valve 1 and a cylinder head 4. Further, the upper end of each intake valve 1 is connected to each low-speed rocker arm 6, 6 provided corresponding to each intake valve 1.
... (see Fig. 4(a)) - end portions 6a, 6a...
It is connected to the.

As shown in FIGS. 2 and 3, both ends of a rocker shaft 80 are fixed to support portions 7, 7 provided on the cylinder head 4 corresponding to each cylinder. Two eccentric bushes 10 are fitted to the rocker shaft 8 so as to be eccentric and rotatable relative to the rocker shaft 8, respectively. The low-speed rocker arm 6 and the high-speed rocker arm 11 (see FIG. 4(b)) are fitted to the outer periphery of each eccentric bushing 10 so as to be adjacent to each other and swing independently of each other.

The low-speed rocker arm 6 includes a roller follower 14 that comes into contact with a low-speed cam 13 provided on the camshaft 12.
is rotatably attached by a pin 15. The high-speed rocker arm 11 is in contact with a high-speed cam 16 provided on the camshaft 12 adjacent to the low-speed cam 13, and is urged toward the high-speed cam 16 by a spring 17 via a retainer 18. There is. High speed cam 1
6 has a larger lift amount than the low speed cam 13,
In addition, the intake valve 1 is designed to be open for a longer period than the low speed cam 13. In addition, the camshaft 12
is rotatably supported by a journal portion 20 formed on the cylinder head 4 and a cam cap 21 fixed to the cylinder head 4.

The eccentric bush 10 is integrally provided with an HLA contact arm portion 22 as a contact portion, and the HLA contact arm portion 22 is connected to the low speed rocker arm 6 and the high speed rocker arm 11.
Each rocker arm 6/1 is inserted through each notch formed in the
It protrudes outside of 1. A spherical recess 23 is provided on the lower surface side of the HLA contact arm 22, and a hydraulic lash adjuster (LA) 24 is provided in this recess 23.
The spherical upper ends of the two are in contact with each other. Further, above the HLA abutting arm section 22, when the eccentric bushing 10 rotates a predetermined amount in the B direction, the HLA abutting arm section 22 abuts against each other, thereby controlling the amount of rotation of the eccentric bushing 1o in the B direction. A limiting plate 25 is arranged. In addition, by rotating the eccentric bushing 10 in the B direction by the HLA 24, which will be described in detail below, the low-speed rocker arm 6 and the high-speed rocker arm 11 rotate in the C direction with one end 6a of the low-speed rocker arm 6 as a fulcrum. In other words, when each rocker arm 6, 11 rotates toward the side approaching each cam 13, 16, the double-ended locking arm 6, 11 moves from the eccentric bushing 10.
The force is mainly transmitted near the D portion, but the eccentric bushing 10
The angle θ between part E, which is the part with the minimum thickness, and the above part
is set in the range of 60 to 120 degrees.

The HLA 24 is a cylindrical support portion 2 provided in the cylinder head 4.
an outer cylinder 27 that is fitted and supported by the outer cylinder 6; and an inner cylinder 28 that is slidably fitted into the outer cylinder 27 and whose spherical upper end abuts the recess 23 of the HLA contact arm 22. It is equipped with A reservoir chamber 30 is formed within the inner cylinder 28, while a hydraulic chamber 31 is formed between the inner cylinder 28 and the outer cylinder 27 below the reservoir chamber 30, and furthermore, the reservoir chamber 30 and the hydraulic chamber 3
A communication hole 32 is provided between the two chambers 30 and 31 so that the two chambers 30 and 31 can communicate with each other. A check ball 33 is arranged in the hydraulic chamber 31 below the communication hole 32 to allow oil to flow only from the reservoir chamber 30 to the hydraulic chamber 31 side.
The inner cylinder 28 is a retainer 34 that holds the check ball 33.
It is urged upward by a spring 35 via.

Each low speed rocker arm 6 and each high speed rocker arm 1
A hydraulic plunger type engagement/disengagement mechanism is provided between the two. That is, cylinder portions 36 are provided at corresponding positions in the low-speed rocker arm 6 and the high-speed rocker arm 11, respectively.
・37 is formed in the axial direction. A plunger 38 is fitted into the cylinder portion 37 so as to be movable into the cylinder portion 36, and furthermore, a hydraulic chamber 39 is formed between the plunger 38 and the cylinder portion 37. The plunger 38 is biased toward the hydraulic chamber 39 by a spring 41 disposed within the cylinder portion 36 and an air hole 40 provided continuously therewith. Oil is supplied to and discharged from the hydraulic chamber 39 through an oil passage 42 provided within the rocker shaft 8.

When the entire plunger 38 is housed in the cylinder portion 37, the above-mentioned engagement/disengagement mechanism separates the double-ended locking arms 6 and 11 from each other to allow relative rocking between the double-ended locking arms 6 and 11. On the other hand, when a part of the plunger 38 is moved into the cylinder part 36 by the hydraulic pressure of the oil sent into the hydraulic chamber 39, the double-ended hook arm 6.
11 are connected so that the double-ended hook arms 6 and 11 can be swung together.

In the above configuration, when the engine speed is low, for example, 3,500 revolutions per minute or less, each engagement/disengagement mechanism is connected to each low speed rocker arm 6 and each high speed rocker arm by housing the entire plunger 38 in the cylinder part 37. rocker arm 1
1 are in a separated state.

As a result, each low speed rocker arm 6 is connected to each low speed cam 1.
3, each high-speed rocker arm 11 is driven individually by each high-speed cam 16, but the rocking motion of each low-speed rocker arm 6 is transmitted to each intake pulp 1, and eventually each intake pulp 1 is opened and closed by a low speed cam 13.

On the other hand, when the engine speed is high, for example, 350 rpm
When the rotation exceeds 0, each engagement/disengagement mechanism moves a part of the plunger 38 toward the cylinder part 36 against the biasing force of the spring 41 by supplying oil to the hydraulic chamber 39. The rocker arm 6 and each high-speed rocker arm 11 are brought into a connected state. As a result, the corresponding low-speed rocker arm 6 and high-speed rocker arm 1
However, since the lift amount of each high-speed cam 16 is larger than the lift amount of each low-speed cam 13, the low-speed and high-speed rocker arms 6 and 11 swing together with the high-speed cam 1.
As a result, each intake valve 1 is opened and closed by a high-speed cam 16. Therefore, when the engine is rotating at high speed, the period during which the intake valve 1 is open is longer than when the engine is rotating at low speed, and the lift amount of the intake valve 1 is larger than when the engine is rotating at low speed.

In addition, the cams 13 and 11 corresponding to each locker end 6 and 11
16, the HLA 24 moves oil from the reservoir chamber 30 to the hydraulic chamber 31 while moving the inner cylinder 28 upward by the biasing force of the spring 35, and moves the eccentric bushing 10 around the rocker shaft 8. Rotate in direction B. Along with this, each rocker arm 6, 11 rotates in the C direction using one end 6a of the low speed rocker arm 6 as a fulcrum, and the gap between each rocker arm 6, 11 and each cam 13, 16 is absorbed. be done. Therefore, a good contact state is always maintained between each rocker arm 6, 11 and the corresponding cam 13, 16.

FIG. 5 shows the relationship between the deviation angle in the circumferential direction of each circumferential portion on the outer periphery of the eccentric bushing 10 from the minimum thickness portion E and the amount of increase in thickness at that portion with respect to portion E. As is clear from the figure, the deviation angle from part E is 60
In the range F of ~120°, the amount of increase in the thickness of the eccentric bushing 10 per unit angle is larger than in other ranges. Therefore, as mentioned above, the angle θ formed between the portion E of the eccentric bushing 10 with the minimum thickness and the portion D, which is the portion where force is transmitted from the eccentric bushing 10 to each rocker arm 6 and 11, is set to 6.
When set in the range of 0 to 120@, each rocker arm 6.
Since the rotation angle of the rocker arms 11 in the C direction becomes larger, even if a small HLA 24 is used, sufficient contact between the rocker arms 6 and 11 and the cams 13 and 16 can be maintained.

In addition, in the unlikely event that one of the rocker arms 6 or 11 and the eccentric bushing 10 become locked, the eccentric bushing 1
0 attempts to rotate in the B direction together with the lower car arm 6 or 11, the amount of rotation of the eccentric bushing 10 in the B direction is limited by the stopper plate 25. The amount of rotation of the eccentric bushing 10 in the B direction does not increase so much that the eccentric bushing 10 is separated. Therefore, HLA contact arm 2
2 and the HLA 24, a rotatable state of engagement is maintained at all times.

In the above embodiment, the lift amount of the high-speed cam 16 is made larger than that of the low-speed cam 13, and the period during which the intake valve 1 is opened by the high-speed cam 16 is set longer than that of the low-speed cam 13. The lift amount and the period during which the intake valve 1 is opened may be different between the cam 13 and the low-speed cam 13, and the other may be the same.

In addition, in the above embodiment, the driving device for the intake valve 1 was described, but the driving device for the exhaust valve is similar to the driving device for the intake valve 1, and the period for opening the exhaust valve and the period for opening the exhaust valve when the engine rotates at low speed and when the engine rotates at high speed. /Or the lift amount may be switched, or the exhaust valve opening period and lift amount may be constant over the entire operating range of the engine, in other words, it may be provided with only one type of rocker arm. .

〔Effect of the invention〕

As described above, the engine valve drive device according to the present invention has a plurality of rocker arms that are each driven by an individual cam arranged in parallel, and that connects the adjacent rocker arms so that they can be separated. In an engine valve drive device equipped with a mechanism, there is a rocker shaft, an eccentric bush that is eccentrically provided on the rocker shaft and supports each rocker arm in a swingable manner, and a contact portion provided on the eccentric bush. The structure includes a lash adjuster that is in contact with the rocker arm and biases each rocker arm toward the corresponding cam by biasing the eccentric bushing in one rotational direction.

As a result, since each rocker arm is supported by the rocker shaft via the eccentric bushing, it is possible to reliably prevent each rocker arm from tilting even in a pulp drive device in which multiple rocker arms are installed in parallel. This has the effect that opening/closing control can be performed accurately.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a partial cross-sectional view, FIG. 2 is a plan view, FIG. 3 is a partial vertical cross-sectional view, and FIG. ) is a side view of the low-speed rocker arm, Figure 4(b) is a side view of the high-speed rocker arm,
FIG. 5 is a graph showing the relationship between the deviation angle of each part in the circumferential direction on the outer periphery of the eccentric bush from the minimum thickness part and the amount of increase in thickness of the part with respect to the minimum thickness part. 2 is an intake pulp (pulp), 6 is a rocker arm for low speeds, 8 is a rocker shaft, 11 is a rocker arm for high speeds, 22 is an HLA abutting arm part (abutting part), and 24 is a hydrolink lash adjuster. Patent applicant Mazda Corporation □, −,, −
,,,),--1 Figure 1 Figure 3

Claims (1)

[Claims] 1. In an engine valve drive device in which a plurality of rocker arms each driven by an individual cam are arranged in parallel and a locking/disengaging mechanism is provided between adjacent rocker arms to connect these rockers in a separable manner, the rocker shaft and , an eccentric bushing that is provided eccentrically on the rocker shaft and swingably supports each rocker arm, and an abutting portion provided on the eccentric bushing that biases the eccentric bushing in one direction of rotation. A lash adjuster for biasing each rocker arm toward a corresponding cam.