JPS60113018A - Internal-combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent the occurrence of overheating during high load operation resulting from increase in a speed and an output, by a method wherein the opening time of a suction valve is controlled to the lag side in order to prevent the occurrence of knocking, and cooling water is increased in a circulating amount. CONSTITUTION:In an engine with a supercharger, the engine is constituted such that a high and low speed cam and a low speed cam of cams for a suction valve are switched by a controller when the rotation speed of an engine is increased or decreased to about 2,000-3,000rpm serving as boundary. In linkage with such control, a 3-way electromagnetic valve 59 is switched to the surge tank 60 side, a valve body 56 is moved leftward by means of a diaphragm 51, and cooling water is caused to flow in the radiator side through the both main and auxiliary cooling water passages 31A and 31B.

Description

[Detailed Description of the Invention] [Technical Field] The present invention includes an intake valve operation control device that improves the intake direction by changing the operation timing of the intake valve according to engine operating conditions, and also includes an intake valve operation control device that changes the operation timing of the intake valve according to engine operating conditions. The present invention relates to a supercharged internal combustion engine equipped with a device that changes the amount of engine cooling water circulated.

BACKGROUND TECHNOLOGY> At present, internal combustion engines with a supercharger, such as an exhaust turbo supercharger, increase the amount of intake air in the engine and generate high output by supercharging intake air into the engine with a compressor. As a result of improved performance, output is now being suppressed to prevent knocking rather than to improve supercharging capacity.

Regarding non-king, as shown in FIG. 1, it has been found that the higher the compression ratio and furthermore the higher the compression temperature, the higher the incidence of non-king.

Therefore, conventional measures have been taken to set the compression ratio of a supercharged internal combustion engine slightly low and to delay the ignition timing.

If the ignition timing is delayed in this way, the exhaust temperature will rise, so in order to prevent this, the air-fuel ratio of the air-fuel mixture is enriched, but the decision has been made that it is unavoidable that this will worsen fuel efficiency.

However, as with an exhaust turbo supercharger, the supercharging capacity disappears or decreases during partial loads such as low speeds and low loads, so the above measures have a negative effect in areas where supercharging is not effective, leading to reduced output and worsened fuel efficiency. I'll be there. Therefore,
Although it is desirable to variably control the compression ratio, this is difficult.

By the way, when the closing timing of the intake valve is delayed, the actual compression ratio (hereinafter referred to as the actual compression ratio) changes.

As a result, as shown in FIG. 1, the knocking zone slides to an overwhelmingly high level of supercharging, making it difficult for knocking to occur and achieving high supercharging pressure. However, if the opening timing of the intake valve is changed to increase the overlap with the exhaust valve, the exhaust pressure in an exhaust turbocharger will increase significantly more than the intake pressure (supercharging pressure), as shown in Figure 2. , an exhaust gas backflow phenomenon occurs, reducing charging efficiency and scavenging efficiency, leading to a decrease in output. On the other hand, in a supercharger using a Roots blower, etc., the exhaust resistance is small, so the exhaust pressure does not increase much and the supercharging pressure increases. Therefore, the air-fuel mixture will blow through into the exhaust system during the overramp period, which is undesirable. In this regard, Japanese Patent Laid-Open No. 56-77516 discloses that even if the intake valve closing timing is advanced or retarded, the exhaust valve opening/closing timing and the intake valve opening timing are also greatly changed, resulting in overflow during engine high speeds. Increasing the amount of lamps is disadvantageous.

Furthermore, variable control of the intake valve to close the intake valve at the time when the intake air enters the combustion chamber improves the charging efficiency by utilizing the inertia of the intake air. However, this inertial supercharging has the advantage that it does not receive any external work from the supercharger and therefore does not cause temperature rise. As a result, as shown in FIG. 1, the non-king zone slides even further to a higher level of supercharging, thereby preventing knocking and achieving higher supercharging pressure.

If the knocking margin is improved in this way, it will be possible to advance the ignition timing, so it is expected that the exhaust temperature will decrease as the output increases, and the enrichment of the air-fuel ratio can be reduced accordingly. This makes it possible to improve fuel efficiency.

However, when the intake valve closing timing is delayed in this way to promote high engine speed and high output, if the engine cooling system with the same cooling water route and water volume is used as before, it is likely to lead to a shortage of cooling water at high loads. , the engine is more likely to overheat, seize up, etc.

Additionally, knocking is more likely to occur.

<Object of the invention> In view of the above-mentioned disadvantages of the conventional internal combustion engine with a supercharger, the present invention has been made to
The actual compression ratio is made variable by advancing or retarding the closing timing of the intake valve, and by performing inertia supercharging in conjunction with this, supercharging without temperature rise is possible and the knocking margin is increased. Also,
By keeping the opening timings of the intake valves approximately the same to prevent an increase in overramp, the charging efficiency and the supercharging effect are increased within the non-king margin, and the output direction is improved. In addition to increasing the speed and output of the engine in this way, engine cooling performance is ensured by changing the amount of engine cooling water circulated according to the operation of the intake valve, preventing engine overheating and knocking. etc., to prevent such occurrences.

<Summary of the Invention> For this reason, the present invention provides an internal combustion engine with a supercharger that supercharges intake air to the engine by a compressor of a supercharger installed in the intake system of the engine. A valve operation control device is provided that variably adjusts the valve closing timing of the intake system and adjusts the valve opening timing of the intake valve to be smaller than the change in the valve closing timing, and when the closing timing of the intake valve is controlled to the delayed side. The configuration includes a device that increases the amount of engine cooling water circulated.

<Example> The present invention will be explained in detail below.

3 to 6 show one embodiment of the valve actuation control device according to the present invention.

3 to 5, a camshaft 3 is rotatably supported in a locker room 2 of a four-cylinder internal combustion engine 1, and a rocker shaft 4 is fixedly supported above the camshaft 3. The camshaft 3 has a pair of intake valve operating cams 5A and 5B and an exhaust valve operating cam 6 for each cylinder #1 to #4.
is formed. One of the cams 5A for operating the intake valve is for high speed, and the other cam 5B is for low speed.

A rocker arm 7 that operates the intake valve for each cylinder #1 to #4 is supported on the rocker shaft 4 so that it can freely rotate and slide in the axial direction, and a rocker arm 8 that operates the exhaust valve is freely rotatable. The rocker arm 7 for the intake valve selectively engages one of the high-speed or low-speed cams 58 or 5B by sliding in the axial direction, and the exhaust valve rocker arm 8 is for operating the exhaust valve. It engages with the cam 6 of.

In the case of this embodiment, the ignition order or injection order is #1-#3-
#4-#2, the valve operation switching device includes a holder 9 that integrally holds two rocker arms 7.7 for intake valves corresponding to the #1 cylinder and #2 cylinder, and a holder 9 that integrally holds two rocker arms 7.7 for the intake valves corresponding to the #3 cylinder and #2 cylinder. Two rocker arms for intake valves corresponding to #4 cylinder7.
7, and these holders 9 and 1° are connected to the first and second actuators 11.1, respectively.
2, the rocker arms 7 are selectively engaged with either the high-speed cam 5A or the low-speed cam 5B. The first and second actuators 11.12 have A, B, C, and D boats that are hydraulic oil inlets and outlets for moving the pistons connected to the holders 9 and 10 in the forward or reverse direction, respectively. This is connected to a hydraulic operating circuit as a control device shown in FIG. 6, and is switched and controlled by an electronic control device 20, which also serves as a control device.

That is, in FIG. 6, A of the first actuator 11,
The B boat is connected to an accumulator 15 and an oil tank 16 via an electromagnetic directional switching valve 13, and ports C and D of the second actuator 12 are connected to an accumulator 15 and an oil tank 16 via an electromagnetic directional switching valve 14, respectively. The accumulator 15
Lubricating oil pumped up from an oil tank 16 is introduced into the engine 1 by an oil pump 18 driven by the internal combustion engine 1 or by a separate morph 17 . 19 is a relief valve that controls the discharge pressure of the oil pump 18. The electromagnetic directional control valves 13 and 14 are controlled in response to a detection signal of the engine operating state via an electronic control device 20 such as a microcomputer or by a manual changeover switch. Input signals of the engine operating state of the electronic control device 20 include various signals such as engine rotation speed, vehicle speed, intake pressure, boost pressure, transmission gear position 2, cooling water temperature, oil temperature, electrical load of electrical components, etc. However, in this example, the engine rotation speed (crank angle) signal is selected.

A crank angle reference signal is input.

By the switching operation of each of these electromagnetic directional control valves 13.14, oil is transferred into the accumulator 15 from one of the boats (A or B) of the first and second actuators 11.12.
C or D) to move the piston in one direction, thereby moving the intake valve rocker arm 7 in the axial direction to engage either the high speed cam 5A or the low speed cam 5B, and the intake valve Controls the timing of opening and closing.

Here, the high-speed cam 5A greatly delays the closing timing of the intake valve (for example, 50° to 80° after bottom dead center) as shown in FIG. ).

(As shown in Dl, the closing timing of the intake valve is earlier than the above (
For example, it has a cam shape (also 0° to 30°). Further, the opening timing of the intake valve, which determines the amount of overlap with the exhaust valve, is made approximately equal to, for example, about 0° to 10° before top dead center, so that the amount of overlap with the exhaust valve is small. still,
At this time, the opening timing of the exhaust valve is 40° to 50° before the bottom dead center, and the closing timing is a constant value of 10° to 20° before the top dead center fS.

Next, FIG. 8 shows an embodiment of a cooling device that changes the amount of circulating engine cooling water in response to switching of the valve operation of the intake valve by the valve operation control device configured as described above.

In the figure, a part of the cooling water channel 31 connecting the cooling water outlet of the engine 1 and the cooling water inlet of the radiator is enlarged, and a partition wall 32 is provided in this enlarged part to roughly divide it into two parts, and the main cooling water channel 31A and the sub-cooling water channel 31A are divided into two parts. The water channel 31B is formed in parallel.

A thermostat 33 is installed in each of the main and sub-cooling waterways 31A and 31B to control the amount of water flowing to the radiator according to the temperature of the cooling water.

The thermostat 33 is of a wax type, and a wax case 36 includes solid wax and elastic rubber, and a piston 35 is installed in the center of this rubber. One end of the piston 35 is fixed to a flange 37, and the temperature of the cooling water is adjusted. When the wax undergoes a volume change due to the phase change from solid to liquid due to the rise and expands, the wax case 36 is pushed down as shown in the figure because the piston 35 is fixed.

Therefore, wax case 36. The piston 35 constitutes a thermally responsive member 34.

A valve body 38 is integrally fixed around the wax case 36.
is urged upward by the spring 4o in the spring seat 39 and seats on the valve seat 41, closing the thermostat 33.However, as the wax case 36 is pushed downward in the figure due to the temperature rise, the wax case 36 is integrated with the The valve element 38 is separated from the valve seat 41 as shown in the figure to open the thermostat 33.

Further, on the downstream side of this thermostat 33, the main cooling water channel 31A and the sub-cooling water channel 31B merge.

Also, a partition wall 3 that partitions the main and sub-cooling waterways 31A and 31B.
An opening 32a that communicates the recooling channels 31A and 31B is provided at the upstream side of the second thermostat 32, and is opened and closed by a diaphragm control valve 50 mounted on the outer wall of the cooling channel 31.

The control valve 50 is defined by a diaphragm 51 into a negative pressure chamber 52 and an atmospheric chamber 53, and the atmospheric chamber 53 is always open to the atmosphere through an opening 54. A valve body 56 for opening and closing the opening 32a is connected to the diaphragm 51 via a rod 55. 57 is a sealing member that prevents cooling water from leaking, and 58 is a diaphragm spring.

The negative pressure chamber 52 of this control valve 50 is connected to a three-way solenoid valve 59.
The surge tank 60 is connected to an engine intake pipe section via a check valve 61, and negative pressure from the intake pipe is introduced and stored therein. The three-way solenoid valve 59 connects the negative pressure chamber 52 to the surge tank 6o when switching to the high-speed cam 5A, and connects the negative pressure chamber 52 to the surge tank 6o when switching to the low-speed cam 5B, according to a signal from the electronic control device 20. It is designed to be switched to open to the atmosphere.

Next, the operation of this embodiment will be described.

Now, it is assumed that among the intake valve cams, the cam shapes are formed so that the output torque of the engine is different between the high-speed cam and the low-speed cam with the boundary between 2,000 and 3.00 Orpm in terms of engine rotational speed.

The engine rotation speed is approximately 2.000~3. In a low-speed rotation region of OOOrpm or less, the electronic control unit 20 outputs a switching signal to move the electromagnetic directional switching valves 13 and 14 to the left in FIG. Therefore, the oil in the accumulator 15 is introduced into the B and D ports of the first and second actuators, actuating the pistons to move the intake valve rocker arm 7 to the right in FIG. 4 through the holders 9 and 1°. Then, it is locked with the low speed cam 5B. As a result, the opening timing of the intake valve remains almost the same, but the closing timing is advanced toward the bottom dead center, increasing the effective stroke of the engine piston and increasing the actual compression ratio.

Therefore, although the supercharging pressure does not increase much in this operating range, the actual compression ratio increases more than in other operating ranges, even though the compression ratio is relatively small, which is typical of supercharged engines, resulting in a decrease in output and fuel consumption. This can prevent deterioration of the condition.

Further, when engaged with the low speed cam 5B, the three-way solenoid valve 59 is set to the atmosphere open position in response to a signal from the electronic control device 20, and the negative pressure chamber 52 of the control valve 50 is communicated with the atmosphere. Therefore, the opening 32a of the partition wall 32 is closed by the valve body 56, and the cooling water flowing out from the engine is directed to the thermostat 3.
3, the cooling water flows to the radiator side through only the main cooling water channel 31A, and cooling is performed with the same circulation amount as in the conventional case.

In other words, at low speeds when the intake valve closing timing is controlled to the advanced side, the engine output is small and sufficient cooling can be achieved with the same amount of circulating water as before, so the engine does not become overcooled without increasing the amount of circulating water. That's what I do.

In addition, the engine rotation speed is approximately 2.000 to 3.000 rpm.
In the above high-speed rotation range, exhaust energy increases, the supercharging effect increases, knocking becomes more likely to occur, and the exhaust temperature increases. At this time, the electronic control unit 20 inputs a high speed rotation signal and outputs a switching signal so that the electromagnetic directional switching valves 13 and 14 select the position shown in FIG. For this reason,
The oil in the accumulator 5 is then introduced into the A and C ports of the first and second actuators, and the intake valve rocker arm 7 is moved leftward in the figure to come into contact with the high-speed cam 5A. As a result, the closing timing of the intake valve is delayed away from bottom dead center, the effective stroke of the engine piston is reduced, and the actual compression ratio is lowered. Therefore, as shown in FIG. 1, the supercharging pressure required to enter the non-king region becomes high, and by increasing the supercharging pressure by this amount, it becomes possible to aim for an upward exit direction.

Here, the boost pressure is increased by the turbocharger, but by delaying the closing timing of the intake valve, the delay in the intake air flow due to inertia with respect to the crank angle is absorbed into the cylinder just before the intake valve closing timing. This is also achieved by so-called inertia-based supercharging, which is fed into the cylinder and is not performed by external work such as a supercharger, so it increases the temperature of the intake air fed into the cylinder at the start of compression. I have nothing to do. Therefore, as shown by the dotted line in FIG. 1, the non-king region exists further on the high boost pressure side, and a more sufficient boost pressure can be obtained.

As a result, the decrease in the actual compression ratio can be compensated for by a sufficient boost pressure increase, thereby preventing a decrease in output and deterioration in fuel efficiency.

In this way, although the compression ratio of the engine itself is not made variable, by changing the actual compression ratio it is possible to achieve the same effect as a variable compression ratio.

In the above-mentioned operation, the overramp amount of the opening timing of the intake and exhaust valves is substantially constant because the opening timing of the intake valve and the closing timing of the exhaust valve do not change. Therefore, during the overlap period, the exhaust gas does not blow back due to the exhaust pressure being higher than the supercharging pressure (FIG. 2). This increases the charging efficiency and makes it possible to secure an increase in supercharging pressure necessary to compensate for the decrease in the actual compression ratio.

Furthermore, when the high-speed cam 5A is engaged, the three-way solenoid valve 59 is switched to the surge tank side by the output from the electronic control device 20, and the negative pressure in the surge tank 60 is transferred to the negative pressure chamber 52 of the control valve 50. be introduced. As a result, the diaphragm 51 is displaced to the right in the figure against the elastic force of the diaphragm spring 58, and the accompanying movement of the valve body 56 opens the opening 32a of the partition wall 32, allowing the main and sub-cooling channels to be opened. 3
1A and 31B are brought into communication. Therefore, the cooling water flowing out from the engine is transferred to the main engine by the opening operation of both thermostats 33.
Sub-cooling waterway 31Δ.

31B to the radiator side. As a result, the circulation amount per unit time is increased while the cooling water temperature is controlled as before (approximately 82° C.), and the heat capacity of the cooling water can be increased.

In other words, at high speeds when the intake valve closing timing is controlled to the delayed side,
Since the engine output increases and the engine becomes hot, an excessive rise in temperature of the engine is prevented by increasing the amount of circulating cooling water.

As a result, engine overrun 1 that occurs at high engine speed
− It can prevent seizure and also prevent the occurrence of knocking.

Further, switching control between the high-speed cam and the low-speed cam of the intake valve during engine operation is performed at the timing shown in FIG. Since it is impossible to switch the rocker arm 7 while the rocker arm 7 and the intake valve cam (5A5B) are in contact with each other, the rocker arm 7 cannot be switched.
Al, (As shown in Bl, the switchable range of the rocker arms 7 of each cylinder #1 to #4 is limited. #1 and #2.
Since the rocker arms 7 of #3 and #4 are in pairs, respectively, the rocker arms 7 of #1. Common movable area of rocker arm #2 and #3. In #4, which is also a common movable area, the electronic control unit 20 must perform switching control in a timely manner. Therefore, as shown in FIG. 9 [C1], #1 by the first actuator 11. #3 due to the rocker arm movement time of #2 and the second actuator 12. It is unavoidable that there will be a discrepancy with the rocker arm movement time of #4. If the layerer I of this conversion holder is possible, it is also possible to combine the rocker arms of #1 and #3 and #2 and #4, which have a common and sufficient movable area, so that the rocker arms move together.

It is also possible to use a manual switch as the switching signal for the electromagnetic directional control valves 13, 14 without using the electronic control device 20. However, while the engine is under load, there are high demands on the movement speed and timing of the rocker arm, so for example, if you are aiming for the fitting state just before entering the expressway or the low-speed rotation area, you can change the movement from low-speed to high-speed cam. Make sure to switch. In this way, low speed,
The rocker arm can be switched to a different cam while the base circle of the high-speed cam and the end of the rocker arm are facing each other.

<Effects of the Invention> As described above, according to the present invention, since the intake valve closing timing of a supercharged internal combustion engine is made variable, the actual compression ratio can be made variable, and inertial supercharging can be utilized. Partial supercharging can be performed without temperature rise.

These two effects act synergistically, and the engine can be operated with sufficient supercharging in a region where knocking is less likely to occur, without any reduction in output.

In addition, the change in intake valve opening timing is made small (including 0) so that the valve over-ramp period becomes relatively small,
Since the filling efficiency is thereby improved, the above effects can be further promoted.

Furthermore, in operating regions where the intake valve closing timing is delayed, the amount of engine cooling water circulated is increased, which maintains good engine cooling performance and prevents engine overheating and seizure. can suppress the occurrence of
As a result, engine performance can be improved.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the compression ratio, boost pressure and knocking area of a supercharged internal combustion engine, Figure 2 is a graph showing the relationship between boost pressure and exhaust pressure, Figures 3 to 5 3 shows a part of an intake valve opening/closing actuating device and a valve opening/closing timing adjusting device according to an embodiment of the present invention, FIG. 3 is a plan view of the inside of a locker room, and FIG. 4 is a cross-sectional view of the intake valve opening/closing actuating device. , FIG. 5 is a plan view of the main part showing the relationship between the intake valve rocker arm and the cam, and FIG.
The figure is a hydraulic circuit diagram of a valve opening/closing timing adjusting device according to one embodiment of the present invention, and FIG. 7 shows the opening timing of intake and exhaust valves,
is a graph showing the opening/closing timing of the high-speed intake valve, (B) is a graph showing the valve opening characteristics of the high-speed intake valve and exhaust valve, [C1 is a graph showing the opening/closing timing of the low-speed intake valve, +Dl is the graph for low-speed FIG. 8 is a graph showing the valve opening characteristics of the intake valve and the exhaust valve; FIG.
The figure shows the timing at which the rocker arm of each cylinder can be moved.
IAI is an intake valve lift characteristic diagram, (Bl is a time chart showing the range in which the rocker arm can move, and tc is a graph showing cam lift characteristics. ■...4-cylinder internal combustion engine 5A...Cam for intake valve operation (for high speed) 5B...Cam for intake valve operation (for low speed)
7...Rocker arm 9...Boulder 11...1st
Actuator 12...Second actuator 13
．． 14...Electromagnetic directional control valve 2o...Electronic control device 31A...Main cooling waterway 31B...Subcooling waterway
32... Partition wall 32a... Opening 33... Thermostat 50... Control valve 59... Three-way solenoid valve 60... Surge tank 61 River check valve patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio Sasashima

Claims (1)

[Claims] In a supercharged internal combustion engine in which intake air is supercharged to the engine by a supercharger compressor installed in the engine intake system, the intake valve closing timing is variably adjusted by acting on the intake valve opening/closing device. A valve operation control device is provided that adjusts the valve opening timing to be smaller than the change in the valve closing timing, and a device is provided that increases the circulation amount of engine cooling water when the intake valve closing timing is controlled to the delayed side. An internal combustion engine with a supercharger.