JPH07180513A - Valve control device for engine - Google Patents

Abstract

PURPOSE:To increase torque at low and medium speed ranges of engine by reducing the lift amount of intake and exhaust valves to zero selectively by a variable lifter to vary the valve overlapped amount and opening closing timing of the intake and exhaust valves. CONSTITUTION:Air intake valves 11a to 11d driven by a high lift cam 26 and those 12a to 12d driven by a low lift cam 27 are arranged on the cylinders of an engine 10. Also exhaust valves 13a to 13d driven by a low lift cam 28 and those 14a to 14d driven by a high lift cam 29 are arranged. Then intake and exhaust valves 12b, 13b, 12c, and 13c driven by the #2 and #3 low lift cams 27 and 28 of the 2nd and 3rd cylinders vary the valve overlapped amount and closing timing of the intake and exhaust valves 11a to 11d and 13a to 13d by reducing their lift amount to zero. Thus the engine intake efficiency is increased, and engine torque at low and medium speed ranges can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve control device for an engine, and controls intake and exhaust valves of a high-performance engine which is required to reduce fuel consumption and improve middle and low speed torque in recent years.

[0002]

2. Description of the Related Art As a conventional technique related to the present invention, there is one disclosed in, for example, Japanese Patent Laid-Open No. 4-194331. Explaining this prior art, the amount of overlap between the exhaust valve and the intake valve is reduced when the engine is operating at low speed and low load, and the valve overlap is reduced in the entire operating range when the engine is cold. When, the valve overlap amount is increased.

However, when the engine is started, the engine is running at low speed, and the load is low, it is not enough to reduce the valve overlap amount, that is, because the engine is running at low speed, the intake air is caused by the valve overlap. It was blown into the exhaust port, and the intake efficiency of the engine was reduced, making it impossible to improve torque.

[0004]

Therefore, it is a technical object of the present invention to improve the torque of the engine in the low and middle speed range.

[0005]

In order to solve the above problems, in an engine having a plurality of cylinders, at least two intake valves per cylinder, and at least two exhaust valves per cylinder, the at least two At least one of the intake valves is driven by a high lift cam, at least one remainder is driven by a low lift cam, at least one of said at least two exhaust valves is driven by a high lift cam, and at least one remainder is driven. The lift valve is driven by a low lift cam, and the lift amount of the intake / exhaust valve is selectively set to 0 by a variable lifter so that the valve overlap amount and the opening / closing timing of the intake / exhaust valve can be changed.

[0006]

According to the above-described means, when the lift amount of the intake / exhaust valve is selectively set to 0 by the variable lifter, only the low lift cam can be operated and the valve overlap amount of the intake / exhaust valve can be set to 0. The opening and closing timing of the valve changes depending on the combination of the operation of the high lift cam and the high lift cam.

[0007]

EXAMPLE An example of the present invention will be described with reference to FIG. 1. In each cylinder of the engine 10 having, for example, four cylinders (# 1 to 4) in FIGS. 1 and 2, an intake valve driven by a high lift cam 26 is provided. Intake valves 12a-12d driven by 11a-11d and low lift cam 27, and exhaust valves 13a-1 driven by low lift cam 28.
3d and exhaust valves 14a to 14d driven by the high lift cam 29 are provided. (FIG. 2 shows only the first cylinder (# 1)). Cams 26, 2
7 is disposed on the intake side camshaft 21 and includes cams 28, 2
Numeral 9 is disposed on the exhaust side cam shaft 22 and is driven to rotate. Further, the intake side cam shaft 21 is connected to the exhaust side valve opening / closing phase variable control mechanism 23, and the exhaust side cam shaft 22 is connected to the exhaust side valve opening / closing phase. Through the variable control mechanism 24, each is rotationally driven by a timing belt 25 that engages with a crank pulley (not shown) of the engine 10.

Each intake / exhaust valve 11a-11d, 12a-
A variable lifter 30 as shown in FIG. 3 is arranged at 12d, 13a to 13d, and 14a to 14d. However, as will be described later, in this embodiment, the intake / exhaust valves 12b, 13 driven by the low lift cams of the second and third cylinders (# 2, 3).
In b, 12c, and 13c, since the lift amounts thereof are not variable, the variable lifter 30 may not be provided. As described above, the variable lifter 30 may be provided on some of the intake / exhaust valves or all of the intake / exhaust valves. Whether the variable lifter 30 is provided in the exhaust valve may be appropriately selected depending on the design.

Referring to FIG. 3, the variable lifter 30 provided in the intake valve 11a will be described. (Variable lifters applied to other intake and exhaust valves have the same structure) Intake valve 1
A shim 32 is fixed to the tip of the stem 31 of 1a, and a retainer 34 is fixed below the shim 32 via a cotter 33. Retainer 34 and cylinder head 4 of engine 10
A valve spring 35 is stretched between the valve 5 and the valve 5, and always urges the intake valve 11a toward a valve seat (not shown). That is, the intake valve 11a is closed by the valve spring 35.

A support member 41 and a cylinder member 42 are housed inside a body 40 of the main body of the variable lifter 30, and hydraulic passages 43 and 44 are formed in the body 40 and the support member 41. The body 40 slides vertically through the hole 46 in the cylinder head 45, and the hydraulic passage 43 of the body 40
Communicates with the hydraulic pressure supply passage 47 of the cylinder head 45.

A cylinder 48 is formed in the cylinder member 42 in a direction orthogonal to the stem 31, and the inside of the cylinder 48 is formed by
The third pins 49, 50, 51 slide. In the cylinder 48, a hydraulic chamber 52 is formed on the left side of the first pin 49 in the drawing, and a hydraulic passage 44 of the support member 41 is open. On the other hand, a spring seat 53 is provided on the right side of the third pin 51 in the figure.
A return spring 54 is stretched between and. A through hole 60 is coaxially provided with the stem 31 at the substantially center of the cylinder member 42.
The mover 57 is disposed in the through hole 60 so as to be vertically slidable. The mover 57 has a shim 32 in contact with a lower surface thereof and a retainer 58 in contact with an upper surface thereof, and a spring 59 is stretched between the retainer 58 and an upper bottom surface of the body 40. Further, the mover 57 has a horizontal through hole having the same diameter as the cylinder 48, and has the first to third pins 4
9, 50, 51 can slide.

A spring seat 55 is arranged on the lower surface of the support member 41 in the figure, and a support spring 56 is stretched between the spring seat 55 and the cylinder head 45. The support spring 56 serves to float-support the variable lifter 30 in the hole 46 in the cylinder head 45. 26 indicates a high lift cam. FIG. 5 shows a hydraulic pressure supply system passage to the variable lifter 30 in the first cylinder (# 1). In FIG. 5, the main gallery 15 of the engine 10 to the central hydraulic passage 16
Is substantially the center of the cylinder head 45, and each cam lifter 30
Via hydraulic passage 47. In this way, by making the central hydraulic passage 16 substantially at the center of the cylinder head 45,
The hydraulic pressure can be evenly supplied to the intake side and the exhaust side without any time difference.

The operation of the valve device of the engine will be described with reference to FIG. 6. First, the "A mode" is selected when the engine is started, and from the viewpoint that the intake air amount may be small, all cylinders (# 1 to # 1) are selected. 4) High lift cam 2
The intake valves 11a to 11d and the exhaust valves 14a to 14d driven by 6, 6 and 29 are stopped, and the intake valves 12a driven by the low lift cams 27, 28.
-12d and exhaust valves 13a-13d only operate. That is, the exhaust valve 13 follows the cam lift curve of the exhaust side low lift cam 28 as shown by the solid line 70 in FIG.
a to 13d are operated, and the intake valves 12a to 12d are operated in accordance with the cam lift curve of the intake side low lift cam 27 as indicated by the solid line 71 when the overlap amount is 0.
Further, the intake side valve opening / closing phase variable control mechanism 23 and the exhaust side valve opening / closing phase variable control mechanism 24 do not operate.

By the way, the operation stop of the intake / exhaust valves on the high lift cams 26, 29 side is achieved by the operation of the variable lifter 30 engaged with each valve as shown in FIG.
That is, the supply of the hydraulic pressure from the main gallery 15 to the hydraulic chamber 52 is stopped, the pressure in the hydraulic chamber 52 decreases, and the action of the return spring 54 causes the first to third pins 49, 5 to move.
0 and 51 are urged to the left in the figure. This bias is the first
The process is performed until the left end surface in the drawing, which acts as a stopper for the pin 49, contacts the left bottom surface in the drawing of the cylinder 48. Then, the stem 31, the second pin 50, and the mover 57 are aligned on a straight line. The above movement of the pins 49 to 51 is completed when the high lift cam 26 is in the idle portion. And
When the high lift cam 26 reaches the lift portion, the support spring 56 is moved to a higher degree than the spring constant of the valve spring 35.
The spring constant of is set smaller and the stem 3
Since the first and second pins 50 and the mover 57 are aligned, the lift portion of the high lift cam 26 does not push down the stem 31 (that is, without opening the valve) and the variable lifter 3 is lifted.
0 Push down only the main body. At this time, the spring 59 is compressed, and the stem 31, the mover 57, and the second pin 50 move relatively upward in the drawing while being guided by the first and third pins 49 and 51 in the through hole 60. To do.
(Here, the intake valve 11a driven by the high lift cam 26 of the first cylinder (# 1) has been described as a representative, but the same applies to the other valves.) It is selected in the high speed range and at low load, and from the viewpoint of low engine load,
The low lift cams 2 of the second and third cylinders (# 2, 3) are used from the viewpoint that the intake air amount may be small while the operation of all the valves of the fourth cylinder (# 1, 4) is stopped.
Only the intake valves 12b, 12c and the exhaust valves 13b, 13c driven by 7, 28 are operated.

That is, the exhaust valves 13b and 13c operate according to the cam lift curve of the exhaust side low lift cam 28 as shown by the solid line 72 in FIG. 8, and when the overlap amount is 0, the intake side low lift cam as shown by the solid line 73 continues. The intake valves 12b and 12c operate according to the cam lift curve 27. In the “B mode”, only the exhaust side valve opening / closing phase variable control mechanism 24 operates under linear control (or non-linear control).

Here, the exhaust valves 14b, 1 driven by the high lift cams 29 of the second and third cylinders (# 2, 3).
4c may also be operated (following the cam lift curve of the high lift cam 28 on the exhaust side as shown by the solid line 74 in FIG. 8).
However, also in this case, the cam lift curve shown by the solid line 74 is appropriately shifted by operating the exhaust side valve opening / closing phase variable control mechanism 24.

Next, the "C mode" is selected when the engine is in the low / medium speed rotation range and high load, and the opening / closing control of each valve is the same as the "A mode", but the exhaust side valve opening / closing phase variable control mechanism 24 is used. Only differs in that it activates. The cam lift curves of the low lift cams 26 and 28 on the intake side and the exhaust side are shown by 75 and 76 in FIG. In the "C mode", depending on various engine conditions, all valves may be operated as in the "E mode" described later in order to output a torque that can withstand a high load. In this case, the cam lift curves of the high lift cams 27 and 29 on the intake side and the exhaust side are shown in FIG.
7,78. In either case, the solid line 7
5 or / and the cam lift curve shown by the solid line 77 is appropriately shifted by linearly operating the exhaust side valve opening / closing phase variable control mechanism 24.

Next, the "D mode" is selected when the engine is in the high speed rotation range and the load is low. From the viewpoint of low engine load, all the valves of the first and fourth cylinders (# 1, 4) are operated. The intake valves 11b, 1 driven by the high lift cams 26, 29 of the second and third cylinders (# 2, 3) from the viewpoint of increasing the intake air amount while stopping
Only 1c and the exhaust valves 14b and 14c are operated. That is, the exhaust valve 1 follows the cam lift curve of the high lift cam 29 on the exhaust side as shown by the solid line 79 in FIG.
4b and 14c are activated, and the high lift cam 26 on the intake side as indicated by the solid line 80 continues with an appropriate overlap amount.
The intake valves 11b and 11c operate in accordance with the cam lift curve of In the "D mode", only the exhaust side valve opening / closing phase variable control mechanism 24 operates under the linear control (or non-linear control), and the intake side valve opening / closing phase variable control mechanism 23 also operates and the cam lift curve shown by the solid line 80. To the left in the figure (the side that opens earlier).

Here, the intake valve 12b driven by the low lift cams 27, 28 of the second and third cylinders (# 2, 3) in order to secure the amount of air required for high rotation depending on various engine conditions. , 12c and exhaust valve 13b,
13c may also be activated.

Finally, the "E mode" is selected when the engine is in the high speed rotation range and under high load, and a large amount of intake air is required, and all valves are operated to output torque that can withstand high load. To do. Further, the intake side valve opening / closing phase variable control mechanism 23 is also the exhaust side valve opening / closing phase variable control mechanism 2.
4 also works. The cam lift curve is shown by the solid lines 83 to 8 in FIG.
Shown by 6.

[0021]

According to the present invention, when the lift amount of the intake / exhaust valve that is operated by the high lift cam is set to 0 by the variable lifter, only the low lift cam operates and the valve overlap amount of the intake / exhaust valve is reduced. It can be zero. As a result, in particular, when the engine is started or when the engine speed is low or the engine speed is low and the engine load is low, the intake air is not blown through, the intake efficiency of the engine is increased, and the engine torque is improved in the low to medium speed range.

This is not limited to when the engine is started or when the engine is running at low rotation / low and medium loads, but the valve overlap amount between the intake and exhaust valves and the opening / closing timing can be freely set by appropriately combining the low lift cam and the high lift cam to be operated. It is possible to change it, and it is possible to perform optimum intake and exhaust according to the state of the engine, and it is possible to improve the performance in the entire operating region of the engine.

[Brief description of drawings]

FIG. 1 is a valve layout of a valve control device for an engine according to the present invention.

FIG. 2 is a detailed view of the first cylinder in FIG.

FIG. 3 is a sectional view of a variable lifter.

FIG. 4 shows another state of FIG.

FIG. 5 is a hydraulic circuit diagram of the first cylinder.

[Fig. 6] Operation mode diagram

FIG. 7 is a cam lift curve diagram in A mode.

FIG. 8 is a cam lift curve diagram in B mode.

FIG. 9 is a cam lift curve diagram in C mode.

FIG. 10 is a cam lift curve diagram in D mode.

FIG. 11 is a cam lift curve diagram in E mode.

[Explanation of symbols]

11,12 Intake valve 13,14 Exhaust valve 26,29 High lift cam 27,28 Low lift cam 30 Variable lifter

Claims (2)

[Claims] 1. An engine having a plurality of cylinders, at least two intake valves per cylinder, and at least two exhaust valves per cylinder, wherein at least one of the at least two intake valves is driven by a high lift cam. In addition, at least one of the remaining exhaust valves is driven by a low lift cam, at least one of the at least two exhaust valves is driven by a high lift cam, and at least one of the remaining exhaust valves is driven by a low lift cam, and the intake and exhaust valves are changed. A valve control device for an engine, wherein the lift amount is selectively set to 0 by a lifter and the valve overlap amount and the opening and closing timings of the intake and exhaust valves are made variable. 2. The valve control device for an engine according to claim 1, wherein at least one of the intake and exhaust valves is controlled by a valve opening / closing phase variable control mechanism.