JPS61252811A - Tappet device for engine - Google Patents

Abstract

PURPOSE:To enhance the charging efficiency of a two-intake-valve engine, by using a low speed cam to drive only one intake valve in a low speed range, using a high speed cam to drive only one intake valve in a middle speed range, and using the low speed cam and the high speed cam to drive both intake valves in a high speed range. CONSTITUTION:In an engine having two intake valves for each cylinder, rocker arms 10, 30 are provided for the valves to drive them by a low speed cam and a high speed cam. When the engine is in a low speed range, a valve 24 is opened by a controller 45 to supply pressure oil to a cylinder 21 to engage the small-diameter portion 20 of a selector 13 with the head of a plunger 14 against a spring 22. As a result, the action of the rocker arm 10 is transmitted to one intake valve to open and close it. When the engine is in a middle speed range, the valve 24 is closed but another valve 44 is opened to put the rocker arm 10 out of operation and the other rocker arm 30 in operation to open and close one intake valve by only the high speed cam. When the engine is in a high speed range, the valves 24, 44 are opened to open and close both the intake valves. The charging efficiency of the engine is thus enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a
The present invention relates to a valve operating system for an engine having two valves per cylinder, which can adjust valve lift characteristics and intake swirl according to operating conditions.

(Prior art) When setting the operating characteristics of the engine's intake and exhaust pulp, at low speeds, combustion stability and fuel efficiency are improved by suppressing exhaust blowback and intake air blowback during the pulp overlap period at low speeds. In order to achieve this, it is desirable to make the valve lift height and valve opening period relatively small, and at high speeds, it is desirable to increase the valve lift amount and valve opening period in order to improve output.

In order to satisfy these requirements, a valve train is equipped with multiple cams of different shapes, a valve is selectively linked to one of these cams, and the linkage is switched depending on the operating state. It is known in the past, and this type of valve train is known, for example, from Utility Model Application No. 57-18220.
There is something like the one shown in Publication No. 5. This device has two cams of a low speed type and a high speed type and one rocker arm for one valve, and the cam side portion of the rocker arm is formed into a bifurcated shape, and one end of the rocker arm is formed into a bifurcated shape. One end is used as the abutting part for the low-speed cam, and the other end is equipped with a slidable high-speed cam abutting member and a stopper that prevents the sliding, and this stopper is interlocked with an actuator such as a hydraulic cylinder. It operates through a mechanism. By controlling the actuator according to the operating condition, the high-speed cam abutting member moves loose when the speed is low, and the operation of the high-speed cam is not transmitted to the valve, and the valve is operated by the low-speed cam, and when the speed is high, the high-speed cam contact member moves freely, and the valve is operated by the low-speed cam when the speed is high. Sliding of the cam abutting member is prevented so that the operation of the high-speed cam is transmitted to the valve.

By the way, the above-mentioned conventional device is applicable to an engine in which one intake system or one exhaust system valve is provided for each cylinder.
The lift characteristics of one valve per cylinder are simply changed depending on the operating condition, and the intake valve,
It was not applied to engines with two exhaust valves per cylinder or one or both of them. Particularly in this type of engine, it is desirable to adjust the swirl in the cylinder according to the operating conditions as it also affects the combustibility, etc., but in the past, it was preferable to adjust the valve lift characteristics in combination with the swirl adjustment. I couldn't do it. Furthermore, simply switching the valve lift characteristics between the low speed side and the high speed side tends to cause a drop in torque in the medium speed range near the switching point.

(Object of the Invention) In view of the above circumstances, the present invention has been developed to improve the valve lift characteristics and the swirl within the cylinder in an engine having two valves per cylinder in at least one of the intake system or the exhaust system. Can be adjusted accordingly, especially
We have created an engine valve train that can properly adjust the intake air intake condition in the low, medium, and high speed ranges, and can also prevent torque from dropping in the medium speed range. This is what we provide.

(Structure of the Invention) The present invention provides at least one of the intake system and the exhaust system,
In an engine with two valves per cylinder, a cam group consisting of a plurality of cams including a low-speed cam and a high-speed cam, and control for controlling the coordination between each cam of this cam group and each of the above-mentioned valves. In the low-speed range, only one valve is linked to the low-speed cam, in the medium-speed range, only one valve is linked to the high-speed cam, and in the high-speed range, both valves are linked to the low-speed cam and high-speed cam, respectively. and control means for controlling the control mechanism so as to be linked to the control mechanism.

In other words, the opening time and opening time of the valve relative to the combustion chamber are
The speed can be changed stepwise in the low speed range, medium speed range and high speed range, and sufficient swirl can be obtained from the low speed range to the medium speed range.

(Example) Figures 1 to 3 show an example of the present invention, and the figures show the case where it is applied to an intake valve. In these figures, 1 is a cylinder head, 2 is a cylinder, and this cylinder 2
is equipped with two intake valves 3°4. cylinder 2
is also equipped with an exhaust valve, but the exhaust valve and its drive system are not shown. For both intake pulps 3.4, a cam group consisting of a plurality of cams 6.7.8 is arranged on a camshaft 5, and two sets of rocker arms 10.30 supported on a rocker shaft 9. The drive system consists of these.

The above-mentioned cam group includes two types of cams, a low-speed type and a high-speed type. The mold cam 7 constitutes a cam group. The above low speed cam 6
The cam nose is formed to be small so as to make the valve lift H1 and the valve opening period relatively small, and the high speed cam 7 is designed to have at least one of the valve lift and the valve opening period larger than the low speed cam 6. , the cam nose is formed large.

The double-ended hook arm 10.30 has each cam 6.7.
A control mechanism is provided to control the interaction between the intake valve 8 and each of the intake valves 3 and 4. In this embodiment, each rocker arm 10.30 is provided with a valve stop mechanism as a control mechanism.

This valve stop mechanism will be described in detail with respect to one rocker arm 10. This rocker arm 10 includes a cam-side arm 11 that contacts the low-speed cam 6, and one intake valve 3.
and a valve-side arm 12 that comes into contact with the rocker shaft 9. Both arms 11 and 12 are supported for relative movement around the rocker shaft 9, and both arms 12 can be switched between a connected state and a non-connected state. A selector 13 is incorporated into the rocker arm 10.

The selector 13 includes a plunger 14 and a lever member 1.
5, the concrete structure is as follows. In other words, the valve side arm 1 is attached to the upper part of the cam side arm 11.
A guide hole 16 opening toward the top of 2 is formed,
The plunger 14 is movably accommodated in the guide hole 16, and the plunger 14 is urged by a spring 17 in the guide hole 16 to come into contact with the valve side arm 12. An engaging portion 18 is formed. Further, the lever member 15 is supported on the upper part of the cam side arm 11 so as to be movable in the axial direction of the rocker shaft 9 perpendicular to the plunger 14. A plunger insertion hole 19 having a large diameter and a locking hole 20 having a size corresponding to the engagement portion 18 and connected to the plunger insertion hole 19 are formed. The arm 15 of the lever member 15 is connected to an annular hydraulic actuator 21 provided around the rocker shaft 9 at the end of the lever member 15.
When oil is supplied to this actuator 21 from an oil pump (not shown) through an oil passage 23, the lever member 15 is operated toward the lock position described later, and oil is discharged from the actuator 21. When relieved, the lever member 15 is operated by the return spring 22 toward the unlocked position described later. The actuator for operating the lever member 15 is not limited to the hydraulic type described above, and a solenoid or the like may be used.

In this way, the locking hole 20 of the lever member 15 separates from the engaging portion 18 of the plunger 14, and the plunger insertion hole 19
When the lever member 15 is in the unlocked position where the plunger 14 is inserted, sliding of the plunger 14 is allowed and relative movement of both arms 11 and 12 is allowed (this is a disconnected state). On the other hand, when the lever member 15 is operated to the lock position where the locking hole 20 engages with the engaging portion 18, the sliding of the plunger 14 is prevented, so that the upper portions of both arms 11 and 12 are Relative movement in the direction of approaching each other is prevented (this is when the arms 11 and 12 are in the connected state!).And when the arms 11 and 12 are in the disconnected state, the rotation of the low-speed cam 6 is prevented. The oscillation of the cam-side arm 11 caused by this is not transmitted to the valve-side arm 12, which means that the connection between the low-speed cam 6 and the intake valve 3 is cut off, and the operation of the intake valve 3 is stopped.
2 is in the connected state, the swinging of the cam-side arm 11 accompanying the rotation of the low-speed cam 6 is transmitted to the valve-side arm 12, that is, the intake valve 3 is operated in conjunction with the low-speed cam 6. That will happen.

The pulp stop mechanism of the other rocker arm 30 is configured similarly, that is, the rocker arm 30 is connected to the cam side arm 31.
and a valve-side arm 32, and both arms 31, 32 can be switched between a connected state and a non-connected state by a selector 33 composed of a plunger 34, a lever member 35, etc. 33 is actuated by a hydraulic actuator 41, a spring 42, and the like.

The above control mechanism is based on a microcontroller as a control means.
It is controlled by a control circuit 11-45 consisting of an I-viewer and the like.

This control circuit 45 receives a rotational speed signal 46, etc., and receives, for example, an oil passage 2 for each actuator 21.41.
The operation of each selector 13.33 is controlled by controlling the supply and discharge of oil to each actuator 21.41 via a control valve 24.44 provided at 3.43. In the low speed range, by connecting both arms 11.12 of one rocker arm 1o and disconnecting both arms 31.32 of the other rocker arm 30, one intake valve 3 is connected to the low speed type cam 6.
and stops the other intake valve 4, and in the medium speed range both arms 11.1 of one rocker arm 10
2 is disconnected and both arms 31 and 32 of the other rocker arm 30 are connected, one intake valve 3 is stopped and the other intake valve 4 is connected to the high-speed cam 7.
By connecting the arms 11.12 and 31.32 of each rocker arm 10.30 in the high-speed range, both intake valves 3.4 are connected to each cam 6.7. It's in control.

According to this valve train, the lift characteristics of the intake valve in each of the low speed range, medium speed range, and high speed range are as shown in Figure 4 (a).
(b) It becomes as shown by the solid line in (c). In addition, broken line B
is the lift characteristic of the exhaust valve.

To explain the operation of the valve train with reference to this diagram, in the low speed range, only one intake valve 3 is operated with a relatively small lift amount and valve opening period, as shown by curve A1 in FIG. 4(a). Ru. Therefore, intake air is introduced into the combustion chamber of cylinder 2 through only one of the intake valves 3, causing an intake swirl, and the amount of overlap between the intake valve 3 and the exhaust valve is reduced, causing exhaust blowback and intake air flow. The synergistic effect of these effects improves combustibility at low speeds, improves knock resistance at low speeds and high loads, and improves fuel efficiency and emissions. Further, in the medium speed range, only the other intake valve 4 is operated with a relatively large lift and opening period, as shown by curve A2 in FIG. 4(b). Therefore, by introducing intake air into the combustion chamber only through the other intake valve 4, an intake swirl is generated and the combustion promoting effect is maintained, while the amount of intake air required in the medium speed range is sufficiently allowed to be introduced. The amount of pulp opening into the combustion chamber and the opening time increase.

Furthermore, in the high-speed range, both intake valves 3.4 have their respective predetermined lift characteristics (curves A1.A and 3.4) as shown in FIG.
2) are operated together. Therefore, compared to the medium speed range, the amount of pulp opening into the combustion chamber and the opening time become larger as a whole due to the operation of the intake valve 3 due to the lift characteristic of curve A1, and the multi-layer intake required in the high speed range becomes larger. The introduction will be permitted.

In this way, by properly adjusting the intake air introduction state in each operating range of low speed, medium speed, and high speed, torque is reduced throughout each operating range, and the torque does not drop even in the middle speed range. In addition, since the intake air introduction state changes stepwise as the speed range shifts from low speed to medium speed to high speed, torque shock when operating conditions fluctuate is also reduced.

According to the structure of the above embodiment, a simple structure consisting of one cam 6.7 for each intake valve 3.4 and two sets of pulp stop mechanisms allows the intake air introduction state to be controlled in three stages as described above. Can be adjusted and controlled.

In addition, in the present invention, both intake valves 3.4 and each cam 6.
The specific structure of the control mechanism that controls the linkage with 7 is not limited to the above embodiment, and can be modified in various ways. For example, each rocker arm 10.30 may be integrated, and instead of
By equipping the end of each rocker arm 10.30 that abuts the cam 6.7 with a slidable plunge V and a stopper member that engages with and disengages from this, the operation of the cam 6.7 is absorbed at this end; Each valve stop mechanism may be configured to enable transmission. Also, instead of using two sets of valve stop mechanisms, a pulp stop mechanism is used for one intake valve 3, and a low-speed type valve stop mechanism is used for the other intake valve 4.
Using a link switching mechanism that can selectively link two high-speed type cams, one intake valve 3 is stopped in the low to medium speed range, and the other intake valve 4 is switched to the low-speed type in the low speed range. - The cam may be linked to a high-speed cam in medium and high-speed ranges.

Further, although the above embodiment shows a case where the present invention is applied to an intake valve, the present invention may also be applied to two exhaust valves in an engine in which two exhaust valves are provided per cylinder. In this case, the amount of valve overlap, etc. can be adjusted by adjusting the lift characteristics of the exhaust valve, and if one exhaust valve is stopped, a swirl will be generated in the cylinder, so the cam and All you have to do is control the linkage.

(Effects of the Invention) As described above, the present invention provides an engine in which two valves are provided per cylinder in at least one of the intake system or the exhaust system, in which only one valve is operated by the low-speed cam in the low-speed range. In the medium speed range, only one valve is operated by the high-speed cam, and at high speeds, both valves are operated by the low-speed cam and high-speed cam, respectively, so there are six speed ranges: low, medium, and high speed. It is possible to improve torque over a range of speeds, prevent a drop in torque in the medium speed range, etc., and improve fuel efficiency and emissions.Moreover, the control l1 mechanism has a relatively simple structure. It is something that can be done.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing one embodiment of the device of the present invention, Fig. 2 is a sectional view taken along line II-II in Fig. 1, Fig. 3 is a view of the w11 overlapped part at the rocker shaft position, and Fig. 4 Figures (a) (b)
) (c) is an explanatory diagram of valve lift characteristics in a low speed range, a medium speed range, and a high speed range, respectively. 3.4...Intake valve, 6...Low speed type cam, 7...
・High-speed cam, 10.30...Rocker arm, 13
゜33... Selector (control mechanism), 45... Control circuit (control means). Patent applicant Mazda Co., Ltd. Agent
Patent Attorney Etsushi Kotani Patent Attorney
Long 1) Masamukai Patent Attorney Yasuo Itaya No. 1 Fig. ■1 ■'' Fig. 2 Fig. 3 Fig. 4 Fig. 4 (a) ↑ X4 L Crank #I

Claims (1)

[Claims] 1. In an engine having two valves per cylinder in at least one of the intake system or the exhaust system, a cam group consisting of a plurality of cams including a low-speed cam and a high-speed cam,
A control mechanism that controls the linkage between the individual cams of this cam group and each of the above valves; in the low speed range, only one valve is linked to the low speed cam, and in the medium speed range, only one valve is linked to the high speed cam. A valve train for an engine, characterized in that it is provided with a control means for controlling the control mechanism so as to link both valves to a low-speed cam and a high-speed cam in a high-speed range, respectively.