JP2000073716A - Fluid pressure type variable valve timing mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact variable valve timing mechanism which can prevent the invasion of a foreign article to a changeover control valve, operate the variable valve timing mechanism effectively and process a fluid passage easily, in a fluid pressure variable valve timing mechanism for controlling the fluid by the changeover control valve. SOLUTION: The filter holding hole for a changeover control valve 26 and a changeover control valve holding hole 27 are provided in a cam cap 23 so that both side surfaces 26a, 27a are approached and also one end 32a of a fluid passage 32 for introducing the fluid from the filter for the changeover control valve 25 to the changeover control valve 19 is opened on the side surface 26a of the filter holding hole for the changeover control valve 26 and the other end 32b is opened on the side surface 27a of the changeover control valve holding hole 27 facing to the side surface 26a of the filter holding hole for changeover valve 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic variable valve timing mechanism applied to an internal combustion engine.

[0002]

2. Description of the Related Art Recently, an internal combustion engine having a variable valve timing mechanism capable of freely changing at least one of the opening and closing timing of an exhaust valve and an intake valve has been developed. The variable valve timing mechanism is capable of opening and closing an exhaust or intake valve by freely changing a relative phase difference according to an operation state of the internal combustion engine, etc., and improves output of the internal combustion engine and idle stability. It is aimed at aiming at.

A variable valve timing mechanism of this type is operated by the hydraulic pressure of a fluid guided from a hydraulic pressure source driven by an internal combustion engine via a spool type four-way electromagnetic switching control valve. A hydraulic type has been developed in which the opening and closing timing of at least one of the exhaust valve and the intake valve can be freely changed by controlling the flow rate and direction of the fluid.

The spool-type switching control valve is very weak against foreign substances, and if foreign substances having a diameter larger than the limit enter the spool, the spool may be locked or other malfunctions may occur. When the spool is locked, the variable valve timing mechanism does not operate, which may cause an adverse effect on the engine performance such as an engine stall or a difficulty in starting the engine.

Therefore, it is necessary to remove such foreign matter. However, since the main oil filter in the main fluid path constituting the hydraulic circuit of an automobile is relatively coarse due to pressure loss or the like, the switching control valve is usually used. In some cases, foreign matter that causes a problem cannot be removed. In addition, since the fluid path between the oil filter and the switching control valve requires a certain length in arrangement, there is a high possibility that chips generated at the time of drilling of the fluid path and the like remain. However, this oil filter cannot remove chips.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 9-317412, a finer filter for a switching control valve, which is provided exclusively for the foreign matter which cannot be removed by the oil filter, is provided upstream of the switching control valve. , To prevent foreign matter from entering the switching control valve.
Conventionally, such a switching control valve and an oil filter are often attached to a cam cap due to arrangement in an engine or the like. Specifically, as shown in FIG. 10, one end of a fluid passage 132 formed between the switching control valve and the filter 125 for the switching control valve has one end thereof.
6 is open at the end face 126a, and the other end is the switching control valve holding hole 1
27 is formed so as to open to the side surface 127a.

[0007]

However, such a method has the following disadvantages. In other words, in the conventional method of providing the fluid passage in which one end is opened to the end face of the switching control valve filter holding hole and the other end is opened to the side face of the switching control valve holding hole, the filter holding mechanism for the switching control valve is restricted due to the mounting space restriction. Since the hole and the switching control valve holding hole must be substantially parallel, the fluid passage needs to have a certain length, and the fluid passage must be bent. This increases the possibility that chips generated when drilling the fluid passage remain in the fluid passage between the switching control valve filter and the switching control valve. Further, the processing of the fluid passage is troublesome, and an extra space is required for forming the fluid passage.

[0008] Therefore, in spite of providing the filter for the switching control valve, the chips may invade the switching control valve and cause an operation trouble. Further, the long fluid passage means that the amount of fluid in the hydraulic circuit increases, which also causes a decrease in responsiveness of each hydraulic actuator and a decrease in system pressure.

In addition, in order to draw the fluid from the end face of the filter holding hole for the switching control valve, a process such as making the shape of the tip of the filter for the switching control valve convex in a plan view is performed to secure a fluid passage. In this case, the end face of the filter for the switching control valve comes into contact with the end face of the filter holding hole for the switching control valve at a point, so that the fitting state becomes unstable. Can also occur.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a filter holding hole for a switching control valve and a switching control valve holding hole in a cam cap such that both side surfaces are close to each other. And one end of a fluid passage for guiding fluid from the filter for the switching control valve to the switching control valve is opened on the side surface of the filter holding hole for the switching control valve, and the other end is formed on the side surface of the filter holding hole for the switching control valve. The length of the fluid passage is made as short as possible by opening the side surface of the opposed switching control valve holding hole. Thus, the intrusion of chips remaining in the fluid passage is minimized, and the switching control valve is not adversely affected.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS That is, the present invention is a switching control valve which operates using a hydraulic pressure source driven by an internal combustion engine as a power source and controls the flow rate and direction of fluid introduced from the hydraulic pressure source into the inside. And a switching control valve filter provided upstream of the switching control valve. By controlling the switching control valve to change the flow rate and direction of the fluid, the opening / closing timing of at least one of the exhaust valve and the intake valve is adjusted. In a hydraulic variable valve timing mechanism that can be freely changed, a switching control valve filter holding hole and a switching control valve holding hole are provided in a cam cap such that both side surfaces are close to each other, and a switching control valve filter is provided. One end of a fluid passage for guiding fluid to the switching control valve is opened at the side of the switching control valve filter holding hole, and the other end is connected to the switching control valve filter holding hole. It is characterized in that is opened on the side surface of the switching control valve holding hole facing the side surface. With such a configuration, the length of the fluid passage between the switching control valve holding hole and the filter holding hole for the switching control valve is made as short as possible to the thickness of one wall separating both side surfaces. The switching control valve and the filter for the switching control valve can be provided adjacently to the maximum extent.

Thus, the possibility that chips are left in the fluid passage between the switching control valve and the filter for the switching control valve is minimized, and the operation failure of the switching control valve due to foreign matter contamination is reduced as much as possible. Becomes possible. Further, since the fluid passage is short, the flow rate of the fluid introduced from the hydraulic pressure source is reduced, and the passage can be easily formed, and the size can be reduced.

Further, since the fluid passage is opened on the side surface of the filter holding hole for the switching control valve, as a result, the end face of the filter for the switching control valve is brought into contact with the end face of the filter holding hole for the switching control valve. And the holding state of the filter can be stabilized. Furthermore,
Processing of the end face of the filter for the switching control valve, which has been conventionally performed, can be omitted.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram schematically showing the configuration of an engine 1 (only one cylinder is shown), which is an internal combustion engine, to which the present invention is applied. The engine 1 is, for example, a three-cylinder engine for an automobile, and has an intake system that opens and closes in conjunction with an accelerator pedal (not shown), a fuel injection valve 8 disposed near the end of the intake system for performing fuel injection, and a spark plug. A cylinder 10 includes a combustion chamber 10a for burning an air-fuel mixture by the ignition of the cylinder 9, and an exhaust system leading to a muffler (not shown).

The combustion chamber 10a is provided with an intake valve 2 and an exhaust valve 3 which are opened and closed in synchronization with the engine rotation by a cam mechanism. The valve operating mechanism for the intake and exhaust valves 2 and 3 will be described in detail.
a, 3a, and a valve spring and valve lifters 2b, 3b (not shown) are assembled on the upper portions of the stems 2a, 3a, respectively. Each valve lifter 2b, 3b
, Cams 13 and 14 formed on the intake side camshaft 11 and the exhaust side camshaft 12, respectively, are brought into contact with each other. In this embodiment, as shown in FIGS. 3 and 4, a timing pulley 15 provided at one end of an exhaust-side camshaft 12 and a timing pulley (not shown) provided at one end of a crankshaft of an engine are connected to a timing belt. 16 are connected. Further, the intake side camshaft 11 is connected to the exhaust side camshaft 1 via a variable valve timing mechanism 4 in order to make the opening / closing timing of the intake valve 2 variable with respect to the opening / closing timing of the exhaust valve 3.
It is connected to 2.

The variable valve timing mechanism 4 utilizes a so-called oscillating cylinder mechanism, is driven by hydraulic pressure, and for example, as shown in FIGS. A housing 18 externally fitted to the rotor, and an oil control valve 1 serving as a switching control valve for rotating the housing 18 with respect to the rotor 17
9 (hereinafter referred to as OCV), one is fixed to the housing 18 so as to mesh with each other, and the other is connected to the intake side camshaft 1.
1 and a pair of scissor gears 20 and 21 fixed to the rotor 1. By changing the relative angle of the housing 18 with respect to the rotor 17, an arbitrary rotation phase difference between the exhaust camshaft 12 and the intake camshaft 11 can be obtained. It has a function that can be generated.

More specifically, the rotor 17 has a cylindrical shape, and its inner surface 17a is externally fitted to and fixed to the exhaust side camshaft 12, and, for example, four vanes 2 from the outer surface 17b.
2 protrudes in the radial direction. The housing 18 has a disk shape having a through hole in the center, and is rotatably attached to the rotor 17 by externally fitting the through hole.
The housing 18 has a fan shape in a front view and is provided with four chambers 18a that open to the side surface of the through hole in a point-symmetric manner with respect to the axis. When the housing 18 is fitted to the rotor 17 as described above, Each vane 22 is configured to partition each room 18a into two, an advance chamber b and a retard chamber 18c.

The OCV 19 is a so-called electromagnetic type four-way spool valve having a substantially cylindrical shape as shown in FIG.
One input port 19a, 19b and two output ports 19
c, 19d, the internal fluid path is switched by the reciprocation of the spool 19e, and the output ports 19c, 19d
Is connected to either of the input ports 19a and 19b. Further, at the neutral position of the spool 19e, the internal fluid path is shut off, and the output ports 19c, 1
The communication between the input port 9a and the input ports 19a and 19b is prevented. FIG. 3 shows a state in which the spool 19e is at the neutral position. The movement of the spool 19e is shown in FIG.
Is performed by an OCV drive signal a which is a valve control signal input from the electronic control unit 24 shown in FIG.
On / off duty ratio DV which is the value of CV drive signal a
The advance / retreat distance can be changed according to T.

On the other hand, as shown in FIGS.
OCV filter 2 in main fluid path 34 upstream of
5 are provided. The OCV filter 25 has a cylindrical shape slightly smaller in diameter than an OCV filter holding hole 26 to be described later, and is formed so as to gradually decrease in diameter toward the distal end portion 25a. In addition, a mesh finer than the main oil filter is provided on the side surface 25b,
The fluid flows out from the side surface 25b.

Next, the fluid path relating to the variable valve timing mechanism 4 will be described. As shown in FIG. 4, the output of the hydraulic pump P, which is the power source of the variable valve timing mechanism 4 and is driven by the engine 1,
One input port 19 of the OCV 19 via an oil filter 33 provided inside the OCV filter 25 and the OCV filter 25.
a, and the other input port 19b of the OCV 19 is connected to the tank T.
Also, these output ports 19c, 19d of the OCV 19
Are connected to one ends of two through holes 12a and 12b provided inside the exhaust camshaft 12, respectively. The other ends of the through holes 12a and 12b are connected to the exhaust camshaft 12 respectively.
Are formed in two grooves 12c and 12d provided in parallel with each other in the circumferential direction on the outer surface of the. These grooves 1
2c and 12d are provided at a portion where the rotor 17 is fitted outside. As shown in FIG. 5, the rotor 17 has one end opened to the other groove 12d and the other end partitioned by the vane 22. A first fluid path 17c opening to the advance chamber 18b, and a second fluid opening to one end of the groove 12c and the other end opening to the retard chamber 18c partitioned by the vane 22 as shown in FIG. A path 17d is provided.

By configuring the fluid path as described above, the first state in which the pump P communicates with the advance chamber 18b and the tank T communicates with the retard chamber 18c, and the pump P operates in the retard chamber 18c
The second state in which the tank T communicates with the advance chamber 18b, and the third state in which the pump P and the tank T do not communicate with the retard chamber 18c and the advance chamber 18b, move the spool 19e of the OCV 19 forward and backward. It is realized by doing.

That is, by controlling the OCV 19 to maintain the first state, the fluid is guided to the advance chamber 18b to increase its capacity, and the vane 22 is moved to the chamber 1 as shown in FIG.
8a can be rotated to the most advanced position where it abuts one end. This acts to shift the opening / closing timing of the intake valve 2 described later to the advance side. Further, by maintaining the second state, the fluid is guided to the retard chamber 18c to increase the capacity thereof, and the vane 22 is moved as shown in FIG.
Can be rotated to the most retarded position where it contacts the other end of the room 18a. This acts to shift the opening / closing timing of the intake valve 2 to the retard side. The rotation speed of the vane 22 in these first and second states can be set by the duty ratio DVT of the OCV drive signal a. Further, when the vane 22 is stopped during that time, it may be held in the third state. In this way, the vane 22 is moved from FIG.
Is rotated within the angle range θ shown in FIG. 3, so that the relative angle of the housing 18 to the rotor 17 can be arbitrarily changed within the range of the angle θ.

On the other hand, the intake side camshaft 11 is
The housing 18 is interlocked with the housing 18 via scissor gears 20 and 21, and the exhaust-side camshaft 12 rotates integrally with the rotor 17. Therefore, as described above, the rotational phase difference between the intake camshaft 11 and the exhaust camshaft 12 can be set arbitrarily between the angles θ by changing the relative angle of the housing 18 to the rotor 17 within the range of the angle θ. Become. That is, the variable valve timing mechanism 4 according to the present embodiment changes the opening / closing timing of the intake valve 2 while always opening / closing the exhaust valve 3 at a constant timing with respect to the rotation of the crankshaft. Phase difference between the opening and closing timing of the intake valve 2
It can be freely changed between.

Incidentally, as shown in FIG.
On the more branched fluid path, the main journal of MJ1 to MJ4, the pin journal of PJ1 to PJ3, and IN
A cam journal having 1 to IN4 and EX1 to EX4 is arranged. In this embodiment, the OCV holding hole 27 and the OCV filter holding hole 26 for inserting the OCV 19 and the OCV filter 25 into the cam cap 23 on the timing pulley 15 side are formed in the present embodiment. Are provided such that both side surfaces 26a and 27a of the first and second sides are close to each other. In addition, OCV holding hole 27 and O
It is characterized in that a fluid passage 32 for communicating between both of the CV filter holding holes 26 is provided.

More specifically, the OCV holding hole 27 is bored vertically from one side surface 23a of the cam cap 23 to the side surface, and has a cylindrical shape having substantially the same diameter as the OCV 19. OC
The V filter holding hole 27 is provided by being bored perpendicularly to a side surface 23b of the cam cap 23 facing the side surface 23a, and is arranged in parallel above the OCV holding hole 27. Specifically, the side surface 27a of the OCV holding hole 27 and the O
The side surface 26a of the CV filter holding hole 26 is provided so as to be close to each other with a single wall 29 having a thickness 29a sufficient to divide them. In the OCV filter holding hole 27, the rear end 25 c is fitted into the internal passage 30 a of the union bolt 30, and the OCV filter 25 integrated with the union bolt 30 is screwed by the union bolt 30 penetrating the union collar 31. Is being worn.

The fluid passage 32 has one end 32a opened to the side surface 27a of the OCV holding hole 27 and the other end 32b opened to the side surface 26a of the OCV filter holding hole 26 facing the side surface 27a of the OCV holding hole 27. And is provided perpendicular to both holding holes 26 and 27. Thus, the length of the fluid passage 32 is made equal to the thickness 29 a of the wall 29 that divides the OCV holding hole 27 and the OCV filter holding hole 26.

Next, the flow of the fluid flowing into the OCV 19 will be described. As shown in FIG. 9, the fluid introduced from the external pipe passes through the flow path provided in the union collar 31 and the internal flow path 30 a of the union bolt 30 from the rear end face 25 e of the OCV filter 25. 25. The fluid that has flowed out from the side surface 25 a of the OCV filter 25 flows into the input port 19 a of the OCV 19 through the fluid passage 29.

With the above configuration, as described above, O
The length of the fluid passage 32 between the CV holding hole 27 and the OCV filter holding hole 26 is changed by the side surface 26 of the two 26, 27.
a, 27a can be made as short as possible to a length equal to the thickness 29a of one wall 29. Therefore,
The OCV 19 and the OCV filter 25 can be provided adjacent to each other to the maximum extent, and the size can be reduced.

As a result, the possibility that chips may remain in the fluid passage 32 between the OCV 19 and the OCV filter 25 can be minimized, and malfunctions due to foreign matter in the OCV 19 can be reduced as much as possible. . Further, since the fluid passage 32 is short, the flow rate of the fluid introduced from the hydraulic pressure source is reduced, and since the fluid passage 32 can be provided linearly, the fluid passage 32 can be easily formed.

The fluid flows out to the fluid passage 32 through the side surface 25a of the OCV filter 25. Therefore, the OCV filter 25 does not require any extra processing on its end face 25d.
Of the end face 25d of the filter holding hole 26 for OCV.
b can be brought into contact with the surface, so that the fitting state can be stabilized.

As described above, it is possible to supply the variable valve timing mechanism 4 in which the processing of the fluid path 32 can be easily performed without deteriorating the engine performance due to the entry of foreign matter. In addition, the configuration of each unit is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0032]

The present invention is embodied in the form described above and has the following effects. That is, as described above, the switching control valve filter holding hole and the switching control valve holding hole are provided in the cam cap such that both side surfaces are close to each other, and fluid is guided from the switching control valve filter to the switching control valve. One end of the fluid passage is opened on the side surface of the switching control valve filter holding hole, and the other end is opened on the side surface of the switching control valve holding hole facing the side surface of the switching control valve filter holding hole. The fluid passage can be as short and straight as possible.

Thus, it is possible to prevent a foreign substance from entering the switching control valve, to effectively operate the variable valve timing mechanism, and to realize a compact variable valve timing mechanism in which machining of a fluid path is easy.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram showing one embodiment of the present invention.

FIG. 2 is an overall schematic diagram showing the embodiment.

FIG. 3 is a schematic diagram showing an intake / exhaust-side camshaft portion of the embodiment.

FIG. 4 is a schematic sectional view mainly showing a variable valve timing mechanism of the embodiment.

FIG. 5 is a partial sectional view taken along line AA in FIG. 4;

FIG. 6 is a partial sectional view taken along line BB in FIG. 4;

FIG. 7 is a diagram illustrating the operation of a variable valve timing mechanism.

FIG. 8 is a diagram illustrating the operation of a variable valve timing mechanism.

FIG. 9 is a partial cross-sectional view showing a positional relationship between a switching control valve and a filter for a switching control valve.

FIG. 10 is a partial cross-sectional view showing a positional relationship between a conventional switching control valve and a filter for a switching control valve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine (Engine) 2 ... Intake valve 3 ... Exhaust valve 4 ... Variable valve timing mechanism 19 ... Switching control valve (OCV) 23 ... Cam cap 25 ... Switching Control valve filter (OCV filter) 26: Switching control valve filter holding hole (OCV filter holding hole) 26a: Side surface 27: Switching control valve holding hole (OCV holding hole) 27a: Side surface 32: fluid passage 32a: one end 32b: other end

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Koji Fujii, Inventor F2-1a, Daihatsu Kogyo Co., Ltd. 2-1-1 Taoyuan, Ikeda-shi, Osaka 3G013 AA06 AA07 BB02 BC01 BC02 BC11 BD09 BD14 BD25 BD31 3G015 AA06 AA07 BG01 BG07 BG08 CA12 DA06 DA11 3G016 AA08 AA12 AA19 BA02 BA05 BA22 BA38 CA04 CA13 CA19 CA24 CA33 CA36 CA43 CA44 CA46 CA52 CA59 DA06 DA22 GA00 GA01

Claims (1)

[Claims] 1. A switching control valve which operates using a hydraulic pressure source driven by an internal combustion engine as a power source, and controls a flow rate and a direction of a fluid introduced from the hydraulic pressure source into the inside, and an upstream of the switching control valve. A hydraulic control variable filter for controlling at least one of the exhaust valve and the intake valve by controlling the switching control valve to change the flow rate and direction of the fluid. In the valve timing mechanism, a switching control valve filter holding hole and a switching control valve holding hole are provided in a cam cap so that both side surfaces thereof are close to each other, and fluid is guided from the switching control valve filter to the switching control valve. One end of the fluid passage is opened on the side of the filter holding hole for the switching control valve, and the other end is opposed to the side of the filter holding hole for the switching control valve. A hydraulic variable valve timing mechanism characterized by being opened on the side of the holding hole.