JPH0452411Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a device for controlling the opening/closing timing of intake and exhaust valves of an internal combustion engine. The present invention relates to a hydraulic actuator flow rate control mechanism for a hydraulic actuator in a device that controls the opening and closing timing of intake and exhaust valves, which is set by a hydraulic actuator interposed between the two.

<Prior Art> As a conventional device of this kind, there is, for example, one shown in FIG. 3 (US Pat. No. 4,421,074,
Class 123/90.15 published on December 20, 1983 and "Motafan" December 1982 issue, pages 222-224).

To give an overview of this system, one end of the camshaft 1 is equipped with a cam that opens and closes the engine's intake valve, exhaust valve, both of these, or other opening/closing valves such as a third valve (hereinafter referred to as intake/exhaust valves). A drive wheel 3 is pivotally supported via an actuator 2 so as to be relatively rotatable at a predetermined angle, and the drive wheel 3 is rotationally driven by a crankshaft via a winding transmission medium (not shown) to rotate the camshaft 1. In the hydraulic actuator 2, the ring piston 4 receives the pressure of hydraulic fluid introduced into the hydraulic working chamber 5 via the hydraulic passage 6, and also receives the spring force of the spring 7 that opposes the hydraulic fluid. It is designed to stop at a balanced position. The ring piston 4 has, on its inner and outer peripheral surfaces, inner teeth 8 that substantially mesh with the camshaft 1 and outer teeth 9 that mesh with the drive wheel 3. At least one set of meshes with the other meshes is spirally meshed with each other. As a result, when the ring piston 4 moves in the axial direction, the relative angular phase of the camshaft 1 with respect to the drive shaft 3 is changed, and the opening/closing timing of the intake and exhaust valves relative to the crankshaft is variably controlled.

The flow rate of the hydraulic fluid introduced into the hydraulic working chamber 5 of the hydraulic actuator 2 is controlled by the flow rate control valve 11, and as a result, the pressure is controlled. That is, the flow control valve 11
consists of a hollow sleeve with one end open having an outflow hole 11a, and is attached to the end of the camshaft 1,
The passage area of the relief passage 12 communicating with the hydraulic pressure working chamber 5 is controlled at the right end in the figure.

The flow rate control valve 11 relieves the hydraulic pressure in the hydraulic pressure working chamber 5 by opening the relief passage 12 at the position shown in the third figure, and at this time, the ring piston 4 is moved to the left end position by the biasing force of the spring 7. be.
When the electromagnetic actuator 16 equipped with the output shaft 15 facing the flow control valve 11 is excited from this state, the output shaft 15 moves to the right in the figure, and accordingly the flow control valve 11 also moves to the right to open the relief passage 12. is blocked. Therefore, engine oil pressure is introduced into the hydraulic working chamber 5 and the ring piston 4
moves to the right against the urging force of the spring 7, and the opening and closing timings of the intake and exhaust valves change as described above.

<Problems to be Solved by the Invention> However, according to such a conventional device, the tip of the output shaft 15 of the electromagnetic actuator 16 is exposed inside the rocker cover 17 of the engine where engine oil is scattered. For this purpose, the coil of the electromagnetic actuator 16 is energized or demagnetized,
When the output shaft 15 repeats reciprocating motion inside the electromagnetic actuator 16, pressure fluctuations occur inside the electromagnetic actuator 16, and engine oil is likely to be sucked in when the pressure is negative. If this inhaled engine oil remains inside the electromagnetic actuator 16, it will oxidize and deteriorate due to the heat generated by the engine at high temperatures and the heat generated by the coil when energized, staining the output shaft 15 or solidifying and adhering to it, which can be unpredictable. There is a risk that the output shaft 15 may become stuck at the stroke position.

In addition, even when the engine temperature is low, for example before completion of warm-up, the electromagnetic actuator operates according to the engine operating state, but if the electromagnetic actuator is energized and then de-energized, the return spring (usually elastically restored for low loads) When applying force (which is a fail-safe feature), the viscosity of the engine oil is high, so the output shaft does not return to the specified position and stops in the middle of the stroke, or the period leading to that stop becomes long. It ends up. As a result, the operation of the flow control valve becomes defective, the opening/closing timing of the intake and exhaust valves does not show the desired value, or the transient response deteriorates, and the overlapping amount of the intake and exhaust valves becomes unstable, resulting in high-speed, high-load operation. There was a risk that this would lead to insufficient output in the region or instability of the idle rotation speed.

Of course, if the elastic modulus of the return spring is increased, the above-mentioned disadvantages can be solved, but there arises the disadvantage that the coil device that overcomes this elastic biasing force becomes larger.

In view of the disadvantages of the conventional device, the present invention stops the operation of the electromagnetic actuator when the engine is at high temperature.
The purpose is to prevent the output shaft from becoming stuck due to solidification of engine oil, causing difficulty in drivability, and also to stop the operation of the electromagnetic actuator from the beginning when the engine is cold, and adjust the opening and closing timing of the intake and exhaust valves. The purpose is to clamp to a constant value on the fail-safe side and prevent it from becoming unstable.

<Means for solving the problem> To this end, the present invention incorporates a camshaft with a cam that opens and closes the intake and exhaust valves of an internal combustion engine.
A drive wheel that transmits the rotational driving force of the crankshaft is rotatably supported by a predetermined angle with respect to a camshaft, and a hydraulic actuator is provided between the drive wheel and the camshaft to set a relative angular phase between the two. Intake/exhaust of an internal combustion engine equipped with an electromagnetic actuator that controls a flow rate control valve for hydraulic fluid of the hydraulic actuator by means of an output shaft whose end is exposed inside the engine and which receives an elastic restoring force on the fail-safe side. The valve opening/closing timing control device includes a temperature sensor that detects engine temperature, and a low temperature range where the engine temperature is below a first predetermined value based on a detection signal of the temperature sensor, and a high temperature range where the engine temperature is above a second predetermined value higher than the first predetermined value. means for stopping energization of the electromagnetic actuator in the region to maintain it on the fail-safe side.

<Function> As a result, when the engine is at high temperature, the operation of the electromagnetic actuator is stopped while remaining on the fail-safe side, and the heat generation of the electromagnetic actuator is also stopped, which prevents the output shaft from being contaminated or stuck by overheated engine oil. , the engine is operated with fail-safe intake and exhaust valve opening/closing timing throughout its entire operating range, making it safer.
Furthermore, when the engine is at low temperature, the operation of the electromagnetic actuator is stopped from the beginning, and the opening/closing timing of the intake and exhaust valves is clamped, so that engine control does not become unstable.

<Example> Hereinafter, an example of the present invention will be described based on FIG. 1. The figure shows a cross section of the front end of the camshaft on the left;
An enlarged cross-section of the rear end of the camshaft is shown on the right side, with the middle part omitted, and the internal combustion engine is shown to be of a fuel injection type. An extension shaft 22 is screwed to one end of the camshaft 21, and a sleeve 24 is fitted onto the extension shaft 22 and a stopper 23 press-fitted into the end of the extension shaft 22. An oil seal 26 is installed between the sleeve 24 and the cylinder head 25. A pulley 28 serving as a drive wheel for driving the camshaft is fixed between a protrusion 24a formed on the outer periphery of the sleeve 24 and a nut 27 screwed to the sleeve 24.
Inner teeth 29a of a toothed belt 29, which serves as a wrapping member for transmitting the rotational force of the crankshaft, are engaged with the outer teeth 28a formed in the outer teeth 28a.

Between the stopper 23 and the extension shaft 22, an inner tooth 30a and an inner tooth 30 are formed on the inner tooth 24b formed on the sleeve 24 and the outer tooth 22a formed on the extension shaft 22, respectively.
The ring piston 30 is engaged with the ring piston 30 and is freely movable in the axial direction, and a spring 31 biases the ring piston 30 leftward in the figure. The internal teeth 2
4b and the external teeth 30a, and at least one set of the external teeth 22a and the internal teeth 30b are spirally formed, and the camshaft 21 can be angularly displaced relative to the pulley 28 by movement of the ring piston 30, as in the conventional case. A cover 32 that covers the outside of the pulley 28, toothed belt 29, etc. is connected to a rocker cover 33.

A flow control valve 34 is provided at the opposite end of the camshaft 21 . That is, in the hole 21a formed at the end of the camshaft 21 opposite to the end on which the pulley 28 is attached, there is a valve housing 34b having a valve hole 34a formed in its peripheral wall, and a valve housing 34b.
b, and is slidably inserted into the oil outflow hole 34c.
A hollow sleeve-shaped valve body 34d having a shape formed therein, and a spring 34e that urges the valve body 34d outward.
A flow control valve 34 consisting of the following is installed and is normally open.

An output shaft 41 engages with the end face of the valve body 34d of the flow rate control valve 34, and an electromagnetic actuator 42 for driving the valve body 34d is installed between the rocker cover 33 and the cylinder head 25, and the inner end is connected to the inside of the engine. I'm making it happen.

Further, an oil passage 21b connects the left end surface of the camshaft 21 in the figure with the hole 21a, and an oil passage 21d connects the oil passage 21b with an annular groove 21c formed in a portion of the cylinder head 25 facing the camshaft shaft bearing hole. is formed.

The camshaft bearing portion of the cylinder head 25 is provided with engine oil as a hydraulic medium pumped from an oil pump (not shown) through the annular groove 21c.
An oil passage 25a is formed that leads to.

The extension shaft 22 also includes an oil passage 22b.
is formed, and oil is guided from the oil passage 21b to the left end surface of the ring piston 30 in the figure through the oil passage 22b and the gap between the external teeth 22a and the internal teeth 30b. Therefore, the sleeve 24, the extension shaft 22, the stopper 23, the ring piston 30, and the spring 31 constitute a hydraulic actuator that rotates the camshaft 21 relative to the pulley (drive wheel) 28. A hydraulic pressure working chamber A is formed in.

When a coil 45 is wound around a bobbin 44 and a voltage is applied to the coil 45, the electromagnetic actuator 42 closes the case 46 and the plates 4 at both ends of the coil 45.
7 and the core 48 are excited, the output shaft 41 in the core 48 is moved to the left in the figure, the valve body 34d of the flow control valve 34 is pushed to the left, the valve hole 34a is closed, and the oil passage 21b is opened into the engine. Cut off communication.

As a result, the oil pressure within the hydraulic pressure working chamber A increases.

A large-diameter plunger 51 is formed at the right end of the output shaft 41 in the figure, and the plunger 51 and the core 4
A plunger movement space 52 is formed between the eight ends. Note that the plunger 51 may not be provided. The output shaft 41 is disposed approximately parallel to or coaxially with the camshaft 21, and a core 48 located above the output shaft 41 (axial center) has a first
and second inlets 53, 54 are provided to open into the engine. One first inlet 53 communicates with the plunger moving space 52 via a groove 55 provided in the bobbin 44 and a hole 62 provided in the guide 61 of the plunger 51, and the other second inlet 54 communicates with the plunger moving space 52 through a groove 55 provided in the bobbin 44 and a hole 62 provided in the guide 61 of the plunger 51. The stepped portion 41a and the core 48 communicate with an annular spring chamber 56 in which a return spring 65 is interposed. Here, the return spring 65 elastically urges the output shaft 41 to the right in the figure, and when the coil 45 is deenergized, the output shaft 41 is brought to the right end position and is pushed to the left with respect to the flow rate control valve 34. The timing is matched to the opening and closing timing of the intake and exhaust valves for low loads where no pressing force is applied, and it functions as a fail-safe means.

In addition, first and second outlets 58 and 59 are opened into the engine in the core 48 below the output shaft 41 (the axis thereof). The first outlet 58 communicates with the plunger movement space 52 via a hole 63 opened in the guide 61 and a groove 57 provided in the bobbin 44,
A second outlet 59 communicates with the spring chamber 56 .

The output shaft 41 including the plunger 51 has an internal passage 60 that communicates with the right end surface of the plunger 51, the plunger movement space 52, and the spring chamber 56 through its central axis. This internal passage 60 is
Due to the reciprocating movement of the output shaft 41, the plunger 5
Even if the volumes of the rightmost chamber (which can also be said to be the output shaft end movement space), the plunger movement space 52, and the spring chamber 56 in Figure 1 change, oil flow occurs between them, and as a result, the output shaft 41 Facilitates axial movement.

The electromagnetic actuator 42 energizes or deenergizes the coil 45 as described above by means of a control means 71 that applies a voltage to the terminal 67 of the coil 45 .

The control means 71 is a microcomputer consisting of input/output means, storage means, processing means, etc. The control means 71 includes a rotation sensor 72 that detects the engine rotation speed N by a known means, and an engine load such as an intake air amount Q. , a load sensor 73 that detects fuel injection amount, intake load, intake throttle valve opening, etc., and engine temperature;
For example, engine cooling water temperature T _W engine oil temperature,
Detection signals from a temperature sensor 74 that detects intake air temperature and the like are input. and engine rotation speed N
The control means 71 controls the electromagnetic actuator 42 according to the engine load and the optimum opening/closing timing of the intake and exhaust valves.

The energization of the electromagnetic actuator 42 is stopped by the control means 71 when the temperature T _W detected by the temperature sensor 74 is lower than a first predetermined temperature (for example, the cooling water temperature is approximately 0° C.), for example, in the engine cold region before completion of warm-up. At the same time, the system is also stopped in a high temperature range above a second predetermined temperature (for example, the cooling water temperature is approximately 100°C) after warm-up is completed, and the intake and exhaust valve opening and closing timings are matched for low loads. The return spring 65 elastically urges the output shaft 41 to the right end position. Therefore, the control means 71 functions as means for stopping the operation of the electromagnetic actuator in the above region.

Next, the operation will be explained based on the flowchart shown in FIG.

In S1, the rotation sensor 72 and the load sensor 73
In step S2, the control means 71 receives the detection signal from the temperature sensor 74 and determines the optimal opening/closing timing of the intake and exhaust valves and the fuel injection amount T _P (injection pulse width of the injection valve).
Calculate. The result of this calculation is output as a control signal for a fuel injection valve (not shown) and a energization/de-energization control signal for the electromagnetic actuator 42.

For convenience of explanation and ease of control, control of the optimal opening/closing timing of the intake and exhaust valves by the electromagnetic actuator 42 described below will be performed by selecting either energization or de-energization, and in reality, S3
~ S6 is assumed to be performed based on the determination.

When the electromagnetic actuator 42 is de-energized in S8, the elastic force of the return spring 65 causes the output shaft 41 to be at the retracted right end position as shown in the figure, and the valve body 34d of the flow control valve 34 is moved to the right end position by the spring 34e. Valve hole 34
a is open.

In this state, from the oil passage 25a of the cylinder head 25 to the annular groove 21c of the camshaft 21,
The oil that has flowed into the oil passages 21d and 21b flows out from the hole 21a, via the valve hole 34a of the flow control valve 34, and from the outflow hole 34c.

Therefore, the pressure of the oil flowing from the oil passage 21b into the hydraulic working chamber A through the oil passage 22b and the gap between the external tooth 22a and the internal tooth 30b is small, and the ring piston 30 is moved to the left end position by the biasing force of the spring 31. The opening/closing timing of the intake/exhaust valve mounting portion is controlled according to the relative angular phase between the pulley 28 and the camshaft 21 determined at this position. Specifically, the valve opening overlap amount of the intake and exhaust valves is set small in this case, and matched for low engine speed and low load.

At this time, even if the oil flowing out from the oil outflow hole 34c is scattered around, the toothed belt 29 that drives the pulley 28 is provided at the end opposite to the camshaft 21, so the oil will not flow into the toothed belt 29. It can prevent adhesion. As a result, it is possible to prevent the rubber portion of the toothed belt 29 from deteriorating due to oil, thereby preventing a shift in the opening/closing timing of the intake/exhaust valves and damage due to interference between the intake/exhaust valves and the pistons.

On the other hand, in S7, when a predetermined operating condition is reached, the coil 45 of the electromagnetic actuator 42 is energized, the output shaft 41 begins to extend against the elastic force of the return spring 65, and the valve body 34d is pressed against the spring 34e. The valve hole 34a is closed.

Therefore, the oil pressure introduced into the hydraulic working chamber A increases, and the ring piston 30 is moved by the spring 3.
Pulley 2 moves to the right in the figure against pulley 1.
8, the camshaft 21 rotates by a predetermined angle, and the opening and closing timings of the intake and exhaust valves are shifted by a predetermined crank angle, and are controlled to the opening and closing timings that match the operating conditions. Specifically, in this case, the amount of overlap between the intake and exhaust valves is set to be large to match the engine high speed and high load region.

On the other hand, when viewed from the side of the electromagnetic actuator 42 that controls the opening and closing of the flow rate control valve 34, the output shaft 41
The reciprocating motion in the axial direction acts as a piston, and when the output shaft 41 moves to the right, the oil is transferred from the inlets 53, 54 or the outlets 58, 59 through the groove 55 and hole 62 or the outer peripheral surface of the output shaft 41. When the output shaft 41 moves to the left, the oil that is sucked into the plunger moving space 52 or the spring chamber 56 and flows downward due to its own weight is removed from the hole 63 and the groove 57.
is discharged into the engine through an outlet 58 or 59.

The energization control (S7) of the electromagnetic actuator 42 as described above is performed when the engine operating state is determined in S3 and S4, and when the engine rotation speed N is, for example, 1000 rpm or more and the fuel injection pulse width T _P is 4 ms or more. The de-energization control (S8) is performed in other operating regions.

By the way, regarding the intake/exhaust valve opening/closing timing control which performs the above-mentioned operation depending on the engine operating condition, when the engine is started in a cold region, the temperature of the engine oil is low and the oil viscosity is high. When the engine is operated under high load in this state and the electromagnetic actuator 42 is energized and excited, the output shaft 41 moves to the left due to the large magnetic force, the flow control valve 34 closes, and the opening/closing timing of the intake and exhaust valves changes. However, even if the engine subsequently returns to idle rotation, the viscosity of the oil flowing on the outer circumferential surface of the output shaft 41 (or plunger 51) is too high, and the elastic restoring force of the springs 34e and 65 in the flow control valve 34 and the electromagnetic actuator 42 is insufficient. The output shaft 41 will no longer be able to reach the right end.

Therefore, in S5, the engine cooling temperature T _W is approximately 0°C (first
When the temperature sensor 74 detects a condition below a predetermined value), the control means 71 stops the energization and excitation of the electromagnetic actuator 42 from the beginning of startup (S8), and holds the output shaft 41 at the rightmost fail-safe position.

As a result, the flow rate control valve 34 is kept open and the intake/exhaust valve opening/closing timing is clamped to the fail-safe side of low speed and low load. This means that the stroke position of the output shaft 41 is unspecified, which means that the intake/exhaust valve opening/closing timing becomes unstable depending on the engine operating condition, but instead of the conventional fixed opening/closing timing, which prevents deterioration of combustion in all operating ranges. I can do it,
In addition to improving fuel efficiency, stable rotational speed and output values can be obtained, and engine drivability can be improved.

On the other hand, for example, when the engine is continuously operated under high load in the summer, the engine generates a large amount of heat and the temperature of the engine oil increases. When the electromagnetic actuator 42 is energized in this state and the coil 45 generates heat, the engine oil in the electromagnetic actuator 42 is overheated and solidified, which tends to adhere to the output shaft 41 and cause a stick. This is likely to occur when the engine is in a high load state, and is unsuitable for low load applications, making it difficult to operate the engine. So S6
For example, if the engine cooling water temperature T _W is 100°C (second
If the temperature exceeds a predetermined value), the electromagnetic actuator 42 is de-energized and the return spring 6 is turned off.
5, the output shaft 41 is clamped at the right end position, and the output shaft 4 is
By preventing the 1st stay, it is possible to prevent deterioration of engine drivability and ensure safety.

In the above embodiment, the bobbin 44 has grooves 55,
It is clear that instead of forming grooves 57, the core 48 could be provided with grooves and the same effect would occur.

Also, the outlet 59 provided in the core 48 may be omitted. In that case, the oil introduced into the spring chamber 56 is guided into the plunger movement space 52 through the gap between the core 48 and the output shaft 41.

<Effects of the invention> As described above, according to the invention, the engine temperature
Since the electromagnetic actuator stops operating when the temperature is below a predetermined temperature, the opening/closing timing of the intake and exhaust valves becomes stable, which in turn stabilizes combustion and prevents deterioration of fuel efficiency, which stabilizes engine rotation and output and prevents deterioration of drivability. It can be prevented.

In addition, when the engine temperature is higher than the second predetermined temperature, the operation of the electromagnetic actuator is stopped and the opening/closing timing of the intake and exhaust valves is clamped to the fail-safe side, preventing the output shaft from stalling by stopping the heat generation of the electromagnetic actuator. Deterioration of drivability can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing the configuration of an embodiment of the present invention. FIG. 2 is a flowchart showing a specific example of the operation of the above embodiment, and FIG.
The figure is a sectional view showing the main part configuration of a conventional example. 21...camshaft, 21a...hole, 21
b, 21d...oil passage, 21c...annular groove,
25a...Oil passage, 28...Pulley, 29...
...Toothed belt, 30...Ring piston, 30a
...External tooth, 30b...Internal tooth, 31...Spring, 34...Flow control valve, 34a...Valve hole, A...
...Hydraulic pressure working chamber, 41...Output shaft, 42...
Electromagnetic actuator, 71...control means, 74...
...Temperature sensor.

Claims (1)

[Scope of Claim for Utility Model Registration] A camshaft that has a cam that opens and closes intake and exhaust valves of an internal combustion engine, and a drive wheel that transmits rotational driving force of a crankshaft is supported rotatably at a predetermined angle with respect to the camshaft. , a hydraulic actuator is interposed between the drive wheel and the camshaft to set the relative angular phase between the two, and the output shaft whose end is exposed inside the engine and receives an elastic restoring force on the fail-safe side An intake/exhaust valve opening/closing timing control device for an internal combustion engine equipped with an electromagnetic actuator that controls a flow rate control valve for hydraulic fluid of a hydraulic actuator includes a temperature sensor that detects engine temperature, and a temperature sensor that detects the engine temperature based on the detection signal of the temperature sensor. Means is provided for stopping energization of the electromagnetic actuator and maintaining it on the fail-safe side in a low temperature region where the temperature is below a first predetermined value and a high temperature region where the temperature is above a second predetermined value higher than the first predetermined value. An intake/exhaust valve opening/closing timing control device for internal combustion engines.