JP2001152848A - Internal combustion engine - Google Patents

Abstract

(57) [Summary] [Problem] To realize an optimum combustion chamber peripheral wall temperature under each engine operating condition instantaneously even if the engine operating condition changes suddenly. A sealed cooling path having a portion covering the periphery of an engine combustion chamber and circulating a refrigerant by a pump,
The control device 22 includes a condenser 20 for cooling and liquefying a gas-phase refrigerant by engine combustion heat, and valve means 14 for adjusting the pressure of the gas-phase refrigerant according to a command value.
However, the pump 13 is driven so that the liquid level of the liquid-phase refrigerant covering the periphery of the engine combustion chamber is kept constant, and the command value is controlled so that the refrigerant pressure becomes a target value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine, and more particularly to an engine having a boiling cooling system.

[0002]

2. Description of the Related Art Internal combustion engines (hereinafter also referred to simply as "engines")
The water-cooled cooling system has a sealed structure, the periphery of the engine combustion chamber is filled with liquid-phase refrigerant, and the engine combustion heat causes a phase change from the liquid phase to the gaseous phase, thereby cooling the periphery of the engine combustion chamber. There is known a boiling cooling system in which a cooled refrigerant is returned to a liquid phase again by a condenser and circulated (refer to JP-A-5-296055 as this type of device).

[0003]

By the way, in the engine cooling system, the engine friction is reduced (for the purpose of improving fuel efficiency) and the exhaust temperature is increased (for fuel reforming) in the middle and low speed range and the middle and low load range. In order to increase the gas temperature before ignition (to improve the combustion state), etc., the temperature of the peripheral wall of the engine combustion chamber is raised to a higher temperature. It is required to set the temperature of the peripheral wall of the engine combustion chamber to a low temperature in order to improve the durability of the main motion system and the like. Note that is not required for all organizations. For example,
Is important for improving the actual compression ratio in the case of a self-ignition gasoline engine.

[0004] Therefore, if the engine load is taken on the horizontal axis, the demand for the temperature of the peripheral wall of the engine combustion chamber will be close to horizontal and slightly upward to the right in the upper part of FIG. 18, and the boiling cooling system (see the broken line) is better. Since the temperature of the peripheral wall of the engine combustion chamber can be increased on a lower load side than the flowing water cooling system (see the solid line), the above requirement can be satisfied well. In the boiling cooling system, the refrigerant pressure in the cooling path is increased at a low load so as to obtain the temperature characteristic of the peripheral wall of the engine combustion chamber shown in the upper part of FIG. reference). This is because the lower the refrigerant pressure, the more active the evaporation, the greater the heat energy taken from the peripheral wall of the engine combustion chamber. This is because, in order to lower the temperature to about the same level, it is necessary to lower the refrigerant pressure in the high load range than in the middle and low load ranges and increase the amount of heat energy taken from the peripheral wall of the engine combustion chamber.

[0005] When an engine equipped with a boiling cooling system is used for a vehicle whose engine operating conditions change drastically, the refrigerant pressure is changed from a high pressure to a low pressure in accordance with the engine operating conditions which change drastically, that is, during rapid acceleration. In the case of rapid deceleration, it is necessary to instantaneously change the refrigerant pressure from a low pressure to a high pressure.

However, the conventional apparatus does not have a means for instantaneously changing the refrigerant pressure in response to such a transient situation in which the engine operating conditions change drastically, so that rapid acceleration or deceleration is performed. Sometimes, the temperature of the peripheral wall of the engine combustion chamber does not meet the requirements of the engine operating conditions, and there is room for improvement in terms of fuel efficiency, output, exhaust, and durability reliability. For example, if the refrigerant pressure cannot be instantaneously reduced during rapid acceleration, the charging efficiency will not be improved, and the desired engine output will not be obtained. Endurance reliability of the main motion system and the like is deteriorated.

When the refrigerant pressure cannot be instantaneously increased during rapid deceleration, the engine friction is reduced.
Neither increase in exhaust temperature nor increase in pre-ignition gas temperature can be expected. Unless engine friction is reduced, fuel efficiency will deteriorate. Further, the reforming of the fuel does not proceed unless the exhaust gas temperature rises, and the combustion state is not improved unless the gas temperature before ignition rises.

Accordingly, the present invention provides a valve means for adjusting the refrigerant pressure of the gaseous refrigerant, and controls the valve means so that the refrigerant pressure becomes a target value, whereby the engine operating conditions change rapidly. Even so, an object of the present invention is to instantaneously realize an optimum combustion chamber peripheral wall temperature under each engine operating condition.

[0009]

According to a first aspect of the present invention, there is provided a closed cooling path having a portion (for example, a water jacket) covering the periphery of an engine combustion chamber and circulating a refrigerant by a pump, and a gas phase generated by engine combustion heat. A condenser for cooling the liquefied refrigerant to liquefy it, and valve means (for example, a pressure regulating valve) capable of adjusting the pressure of the gasified refrigerant in accordance with a command value;
Means are provided for driving the pump so that the liquid level of the liquid-phase refrigerant covering the periphery of the engine combustion chamber is kept constant, and means for controlling the command value so that the refrigerant pressure becomes a target value.

In a second aspect of the present invention, in the first aspect, the valve means is provided near a portion from which the gaseous refrigerant flows.

In a third aspect of the present invention, in the first or second aspect, the target value is a value which is large in a low load region and is small in a high load region.

According to a fourth aspect, in the third aspect, a fan for forcibly cooling the condenser is provided, and the cooling fan is controlled so that the rotation speed thereof becomes a target value.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, there is provided means for detecting the refrigerant pressure, and the command value is feedback-controlled so that the detected value matches the target value. I do.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, a normally-closed on-off valve is provided near a portion where the refrigerant in the gaseous phase flows out and upstream of the valve means. And the on-off valve is opened under conditions that require a rapid increase in condensation capacity.

According to a seventh aspect of the present invention, in the sixth aspect, the condition in which the rapid increase of the condensing capacity is required is performed in a region where the engine load is equal to or less than a predetermined value and the rate of change of the engine load is equal to or more than a predetermined value (that is, low). During sudden acceleration from a load).

According to an eighth aspect, in the seventh aspect, the engine load is a throttle valve opening, an intake air amount, or a fuel injection amount.

According to a ninth aspect, in the seventh or eighth aspect, the condition in which the rapid increase in the condensing capacity is required is set for each engine operating condition.

In a tenth aspect, in any one of the sixth to ninth aspects, the target value of the rotation speed of the cooling fan is corrected to be increased under the condition that the rapid increase in the condensation capacity is required.

According to an eleventh aspect of the present invention, in any one of the sixth to tenth aspects, when the pump is operating, the above-mentioned condition that a sudden increase in the condensation capacity is required is satisfied. Temporarily stop the operation of the pump.

According to a twelfth aspect, in any one of the first to eleventh aspects, a relief valve is provided in a passage that bypasses the valve means.

According to a thirteenth aspect, in any one of the first to twelfth aspects, the liquid-phase refrigerant is moved from the cooling path to the reservoir tank when the engine is stopped, and the inside of the cooling path is moved when the engine is started. When returning the refrigerant from the reservoir tank into the cooling path after the evacuation, the suction negative pressure downstream of the throttle valve is used for evacuation in the cooling path.

According to a fourteenth aspect, in any one of the sixth to twelfth aspects, the vacuum negative pressure of the downstream of the throttle valve is used to evacuate the vacuum vessel.

According to a fifteenth aspect, in any one of the first to fourteenth aspects, a superheater for heating the gas phase refrigerant having passed through the valve means with engine exhaust gas, and a gas phase superheated by the superheater A turbine that converts heat energy of the refrigerant into mechanical energy.

[0024]

In the first and second aspects of the present invention, when the command value of the valve means is changed, the refrigerant pressure in the gas phase changes without a response delay. Therefore, by controlling the command value of the valve means so as to obtain the target value of the gas-phase refrigerant pressure, even when the target value changes rapidly, the gas-phase refrigerant pressure is immediately controlled in accordance with this. it can. Therefore, if the target value is determined according to the engine operating conditions (engine speed, engine load), even if the engine operating conditions change suddenly, the optimum peripheral portion of the combustion chamber under each engine operating condition is instantaneously obtained. Wall temperature can be realized.

When the target value is a large value in a low load region, the temperature of the peripheral wall of the engine combustion chamber is high. On the other hand, when the target value is a small value in a high load region, the temperature around the engine combustion chamber is small. According to the third invention, the refrigerant pressure is immediately controlled to the target value because the temperature of the part wall decreases,
The temperature of the peripheral wall of the combustion chamber also changes responsively from a high temperature state in a low load area to a low temperature state in a high load area. Due to this favorable response, the temperature of the peripheral wall of the combustion chamber rapidly drops to a low temperature during rapid acceleration, whereby sufficient engine output can be obtained and durability reliability can be increased.

Similarly, when the target value suddenly changes from a small value in a high load region to a large value in a low load region, the refrigerant pressure is immediately changed to a large target value in accordance with this. This allows the temperature of the peripheral wall of the combustion chamber to change responsively from a low-temperature state in a high-load area to a high-temperature state in a low-load area. With this good response,
At the time of rapid deceleration, the temperature of the peripheral wall of the combustion chamber quickly rises to a high temperature, thereby improving the fuel reforming, improving the combustion state, and improving the fuel efficiency.

According to the fourth aspect of the present invention, the target value is set so as to increase as the load increases, and as the load increases, the rotation speed of the cooling fan increases and the capacity of the condenser increases. Particularly at the time of rapid acceleration, the target value of the refrigerant pressure can be realized with higher response. Further, by setting the target value small in a low load region in which the condenser capacity of the condenser is sufficient, the rotation speed of the cooling fan decreases, so that the driving loss of the cooling fan can be reduced.

According to the fifth aspect, after the feedback control is advanced, there is no influence from variations in production and deterioration over time.

According to the sixth, seventh and eighth aspects of the present invention, when the on-off valve is opened, the cooling path filled with the gas-phase refrigerant communicates with the vacuum vessel upstream of the valve means, and the refrigerant pressure drops rapidly. Therefore, even during rapid acceleration from a low load, which is a condition that requires a rapid increase in condensation capacity, the refrigerant pressure can be responsively shifted to the low pressure side (thus, the temperature of the peripheral wall of the engine combustion chamber can be shifted to the low temperature side). ) Can be changed.

According to the ninth aspect of the present invention, it is conceivable that the condition under which the rapid increase in the condensation capacity is required depends on the engine operating conditions (engine speed and engine load) at that time. The conditions that require a high condensing capacity can be accurately determined even if the engine operating conditions are different.

According to the tenth aspect, since the capacity of the condenser is increased by increasing the target value of the rotation speed of the cooling fan, the response under conditions that require a rapid increase in the condensation capacity is further improved. Can be

According to the eleventh aspect, it is possible to further improve the response of the refrigerant pressure to the low pressure side, although it is limited to the case where the pump is operating.

According to the twelfth aspect, even if the valve means fails, the refrigerant pressure does not become higher than the specified pressure by opening the relief valve.

According to the thirteenth and fourteenth aspects, a vacuum pump for evacuating the cooling path and evacuating the vacuum vessel can be eliminated.

According to the fifteenth aspect, waste heat can be recovered.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG.
And 3 are an intake passage and an exhaust passage, respectively, and 4 is an engine combustion chamber. 6A and 6B are a cylinder block and a cylinder head, respectively.
A water jacket 8 for cooling the peripheral wall of the engine combustion chamber. The water jacket 8 forms a closed-loop cooling path together with various passages described later, and in this case, cooling water is sealed as a refrigerant in this case. The cooling passage is sealed from the outside, and the inside thereof is filled only with liquid or gas phase cooling water, and air is excluded.

The inflow passage 9 to the water jacket 8 is connected to the outlet side of the electric water pump 13, while the steam outlet portion 12 at the top of the water jacket 8 is connected to a condenser (condenser) 20 via a steam passage 11. I have.

The cooling water which has become saturated steam by receiving the engine combustion heat in the water jacket 8 is cooled by air in the condenser 20 and condensed. Reference numeral 21 denotes a fan device for supplying forced cooling air to the condenser 20, and a control device 22 described later.
The operation is controlled by a command from.

The cooling water in the liquid phase in the condenser 20 is sucked by the pump 13 through the passage 19, and is again supplied to the water jacket 8 of the engine through the inflow passage 9 to the water jacket 8.

On the other hand, immediately downstream of the steam outlet section 12, a butterfly type pressure regulating valve 14 (valve means) driven by a step motor 15 is provided. This pressure regulating valve 14
The opening is controlled continuously and variably based on a command from the control device 22, and functions as a refrigerant pressure adjusting unit together with the cooling fan 21.

Reference numeral 17 denotes a normally-closed relief valve.
4 is opened when the refrigerant pressure at the steam outlet 12 (hereinafter simply referred to as “refrigerant pressure”) becomes higher than the valve opening pressure (specified pressure) by the spring, and excessive pressure is released from the bypass passage 16.
To the downstream of the pressure regulating valve 14. This is provided as a measure for fail-safe of the pressure regulating valve 14.

The control device 22 includes an engine rotation speed signal and an engine load signal detected by a sensor (not shown), a refrigerant pressure signal detected by a pressure sensor 23 attached to the steam outlet 12, and a liquid level sensor 24. The surface level signal is input together with the temperature signal from the water temperature sensor 25, the pressure signal from the pressure sensor 26 attached to the intake collector 4, and the like, and the control device 22 including a microcomputer performs the following two controls together. Do.

<1> The electric water pump 13 is controlled to open and close based on the liquid level signal from the liquid level sensor 24 to keep the liquid level constant.

<2> The steam path 1 is controlled by the pressure regulating valve 14 so that a target value of the refrigerant pressure according to the engine operating conditions is obtained.
1 and the amount of condensed refrigerant in the condenser 20 is controlled by the cooling fan 21.

First, <2> will be described. In this control, as shown in FIG. 2, the pressure of the pressure regulating valve 14 is increased so that the refrigerant pressure becomes high in the medium and low speed regions and the medium and low load regions, whereas the refrigerant pressure becomes low in the high load region. And the rotation speed of the cooling fan 21 are controlled. Here, FIG. 2 is a graph in which the characteristics of FIG. 18 are shifted to an operation region in which the engine torque and the engine rotation speed are parameters.
The term "low temperature" refers to the temperature of the peripheral wall of the engine combustion chamber. Therefore, if FIG. 2 is taken as the relationship between the engine load and the refrigerant pressure, the characteristics shown in the lower part of FIG. 18 are obtained. If FIG. 2 is taken as the relationship between the engine load and the temperature (the temperature of the peripheral wall of the engine combustion chamber), FIG. It becomes the characteristic of the upper stage.

When the refrigerant pressure is increased, the driving loss of the electric water pump 13 increases, but the engine friction can be further reduced by increasing the temperature of the peripheral wall of the engine combustion chamber. The basic idea is to set the refrigerant pressure at the highest point.However, when comparing the increase in the drive loss of the electric water pump due to the increase in the refrigerant pressure and the reduction of the engine friction in the idle range, the electric water pump Since it is conceivable that the increase in the drive loss is larger than the decrease in the engine friction (due to the leakage characteristics of the electric water pump, etc.), the drive loss of the electric water pump is taken into consideration only in the idling range. It may be set on the low pressure side from the middle and low load range and the middle and low speed range.

The control of the opening of the pressure regulating valve 14 is specifically shown in FIG.
This will be described with reference to the flowchart of FIG. FIG. 3 is for calculating the opening degree θ of the pressure regulating valve 14, and is executed at regular intervals (for example, every 10 ms). It should be noted that other flowcharts to be described later are also performed at regular time intervals (for example, 10 ms).
Needless to say, this is performed every time.

In FIG. 3, in step 1, in addition to the engine operating conditions (engine speed and engine torque), the refrigerant pressure P (detected by the pressure sensor 23) is read. Here, the engine torque is described as a representative value of the engine load, but is not limited to the engine torque. For example, in a gasoline engine, a basic pulse width TP used for calculating a fuel injection pulse width Ti given to a fuel injector or an intake air amount Qa detected by an air flow meter is used as an engine load. The fuel injection amount Qf or the accelerator opening itself determined according to the accelerator opening may be used as the engine load.

In step 2, a target value P0 of the refrigerant pressure is calculated by searching a map having the contents shown in FIG. 4 from the engine speed and the engine torque. The characteristic of FIG. 4 is in accordance with the characteristic of FIG. 2, and the target value P0 is the highest pressure in a predetermined low speed region and low load region as shown in FIG. Has been set. In FIG. 4, 100 kPa is almost the atmospheric pressure.

Steps 3 to 8 are portions for performing feedback control so that the refrigerant pressure P detected by the pressure sensor 23 coincides with the target value P0. That is, in step 3, the difference ΔP (= P−P0) is calculated, and the absolute value of the difference and the allowable value α (> 0) are compared in step 4, and the pressure difference ΔP and zero are compared in step 5. When the pressure difference ΔP exceeds the allowable value α and the pressure difference ΔP is positive (that is, when the refrigerant pressure P is larger than P0 + α)
Reduces the refrigerant pressure by increasing the regulating valve opening θ by a fixed amount Δθ (> 0) (opening by a fixed amount) in step 6. Conversely, when the pressure difference ΔP exceeds the allowable value α and the pressure difference ΔP is negative (that is, when the refrigerant pressure P becomes P0
If it is smaller than -α), the refrigerant pressure is increased by reducing the regulating valve opening θ by a fixed amount Δθ (closed by a fixed amount) in step 7. When the pressure difference ΔP is equal to or smaller than the allowable value α, the process proceeds from step 4 to step 8 to maintain the previous adjustment valve opening θ.

The opening degree θ of the regulating valve thus calculated
Is converted into a command value to the step motor 15 by a flow (not shown), and the pressure control valve 14 is controlled by the step motor 15 to receive the command value so as to have the control valve opening degree θ.

Here, the case where the feedback control is performed has been described. However, the present invention is not limited to this, and open loop control may be performed. For example, an adjustment valve opening is calculated according to the target value P0, and the calculated adjustment valve opening is converted into a command value to the step motor 15 and output.

In order to increase or decrease the refrigerant pressure, the cooling fan 21 is further driven to variably control the amount of refrigerant condensed in the condenser 20. This is because it is necessary to increase the capacity of the condenser 20 in order to condense a large amount of vapor generated in a high load region and to achieve the target value of the refrigerant pressure with good response. That is, as the load becomes higher, the cooling fan 2
By increasing the rotation speed of the condenser 1, the heat transfer coefficient from the refrigerant to the air is increased to increase the capacity of the condenser 20. In a region where the condenser 20 has a sufficient condensation capacity (low load region), the rotational speed of the cooling fan 21 is reduced to reduce the drive loss of the cooling fan 21.

The control of the rotation speed of the cooling fan 21 will be specifically described with reference to the flowchart of FIG. FIG. 5 is for calculating the rotation speed target value of the cooling fan 21.

In FIG. 5, in step 11, the engine operating conditions (engine speed and engine torque) are read, and in step 12, a map having the contents shown in FIG. Calculate. As shown in FIG. 6, R0 is a value that is small in a low load range and increases as the load increases.

The rotation speed target value R0 calculated in this manner is converted into a command value to the actuator of the cooling fan 21 by a flow (not shown), and the cooling fan 21 receives the rotation speed target value R0 by an actuator that receives the command value.
It is controlled to be zero.

Next, the above <1> will be described.
The liquid level kept constant is lower than the top of the combustion chamber 4,
The height covering the exhaust port 3A is set within the range as an upper limit. That is, the liquid level sensor 2 is set to a desired liquid level.
4 are provided. The liquid level sensor 24 outputs an ON signal when the liquid level has not reached a desired liquid level, and outputs an OFF signal otherwise.

The open / close control of the electric water pump 13 based on the liquid level sensor will be specifically described with reference to the flowchart of FIG. 7, the signal of the liquid level sensor 24 is read in step 21, and the signal of the liquid level sensor 24 is examined in step 22. The signal of the liquid level sensor 24 is O
When N (when the desired liquid level has not been reached)
In step 23, the electric water pump 13 is operated, and when the signal of the liquid level sensor 24 is OFF (when the level is equal to or higher than the desired liquid level), step 2 is executed.
In step 4, the electric water pump 13 is brought into a non-operating state.

In this way, the liquid level of the refrigerant is kept constant.

In this embodiment, the liquid-phase refrigerant is moved to a reservoir tank (not shown) when the engine is stopped, and the refrigerant is returned from the reservoir tank into the cooling path when the engine is started. Japanese Patent Application No. 11-159
No. 112). Briefly describing this, a normally-closed shutoff valve 34 is provided in a negative pressure passage 33 that connects the intake collector 2A and the upstream of the condenser 20. The shutoff valve 34 is introduced before the liquid-phase refrigerant is introduced into the cooling path. By opening 34, the cooling path is evacuated by the suction negative pressure developed downstream of the throttle valve 31. 35 is a one-way valve for preventing air from flowing backward from the intake collector 2A into the cooling path.

The flowchart of FIG. 8 is for realizing the open / close control of the shut-off valve 34. In step 31, a signal from an ignition switch (abbreviated as "IGN switch" in the figure) is checked, and the ignition switch is turned on.
If so, the routine proceeds to step 32, where the open experience flag of the shut-off valve 35 is checked. The open experience flag is a status flag indicating whether or not the shut-off valve 34 has been opened, and is initially initialized with the open experience flag = 0 when the ignition switch is switched from OFF to ON. Therefore, the process first proceeds to step 33, and the maximum value is set as the regulating valve opening degree θ. Thus, before the introduction of the liquid-phase refrigerant into the cooling system, the pressure regulating valve 14 is fully opened.

In the following step 34, the temperature T of the water jacket 8 detected by the water temperature sensor 25 and the suction negative pressure Pin detected by the pressure sensor 26 are read, and the water jacket temperature T and a predetermined value T0 are compared in step 35. I do. If the water jacket temperature T exceeds the predetermined value T0, the routine proceeds to step 40, where the shut-off valve 34 is maintained in a fully closed state. This is because if the liquid-phase refrigerant is introduced into the cooling path when the water jacket temperature is high, the liquid-phase refrigerant may reach the boiling point immediately,
At this time, boiling cooling cannot be performed, so that this is avoided.

If the water jacket temperature T is equal to or lower than the predetermined value T0, the process proceeds from step 35 to step 36, and it is determined whether or not the engine has completely exploded based on the engine speed. When the engine has completely exploded, it is determined that a large negative pressure has developed downstream of the throttle valve 31, and in order to check the actual suction negative pressure in step 37, the suction negative pressure Pin detected by the pressure sensor 26 is compared with the suction negative pressure Pin. The predetermined value P1 is compared. Suction pressure Pi
n is equal to or less than a predetermined value P1 (that is, the throttle valve 31
If a large negative pressure has developed downstream), the routine proceeds to step 38, where the shut-off valve 34 is opened. As a result, the introduction of the liquid-phase refrigerant from the reservoir tank to the cooling path is completed, so that the open experience flag of the shut-off valve 34 is set to 1 in step 39, and the current process ends.

By setting the open experience flag to 1, the flow from step 32 to step 40 will be performed from the next time on, and the shutoff valve 34 will be kept in the fully closed state until the engine stops.

It is to be noted that a negative pressure (vacuum) in the cooling passage can be reduced (vacuum) in the cooling path by using the suction negative pressure, and a sufficient suction negative pressure can be expected as in a diesel engine. If not, the cooling path may be evacuated using a vacuum pump. The “negative pressure” is a pressure lower than the atmospheric pressure.

Here, the operation of the present embodiment will be described.

In this embodiment, when the opening of the pressure regulating valve 14 is changed, the refrigerant pressure (the refrigerant pressure at the vapor outlet 12) changes quickly. Therefore, by controlling the opening of the pressure regulating valve 14 so as to obtain the target value of the refrigerant pressure, the target value is changed from a large value in the middle and low speed range and the middle and low load range to a small value in the high load range. Even when the pressure suddenly changes, the refrigerant pressure can be immediately controlled to a small target value. That is, when the target value is a large value in the middle and low speed range and the medium and low load range, the temperature of the peripheral wall of the engine combustion chamber is high, and when the target value is a small value in the high load range, the engine combustion is stopped. Since the temperature of the peripheral wall of the combustion chamber becomes low, the temperature of the peripheral wall of the combustion chamber is raised from the high temperature state in the medium to low speed range and the medium to low load range by immediately controlling the refrigerant pressure to the target value. It responds well to the low temperature condition in the load range.
Similarly, when the target value suddenly changes from a small value in the high-load region to a large value in the medium-low speed region and the medium-low load region, the refrigerant pressure is adjusted to the large-value target value in accordance with this. The temperature of the peripheral wall of the combustion chamber changes responsively from a low temperature state in a high load area to a high temperature state in a medium to low speed area and a medium to low load area.

As described above, the optimum temperature of the peripheral wall of the combustion chamber under each engine operating condition can be instantaneously realized even in response to a sudden change in the engine operating conditions (engine speed, engine load). Sufficient performance can be obtained with respect to fuel efficiency, output, exhaust, and durability reliability even during transient conditions such as sudden acceleration or sudden deceleration in which operating conditions change rapidly. For example, at the time of rapid acceleration, the temperature of the peripheral wall of the combustion chamber rapidly decreases to a low temperature, whereby a sufficient engine output is obtained and the durability reliability is not deteriorated. Further, at the time of rapid deceleration, the temperature of the peripheral wall of the combustion chamber rapidly rises to a high temperature, thereby improving the fuel reforming, improving the combustion state, and improving the fuel efficiency.

FIG. 9 is a control system diagram of the second embodiment.
The vacuum vessel 41 is connected to the steam passage 11 downstream of the steam outlet 12 and upstream of the pressure regulating valve 14.
A normally closed on-off valve (vacuum valve) 42 driven by a step motor 43 is provided at one connection port. The vacuum vessel 41 communicates with the intake collector 2A through a negative pressure passage 44,
A one-way valve 45 for preventing air from flowing from the collector 2A to the vacuum vessel 41 is interposed in the negative pressure passage 44. For this reason, the air that has entered the vacuum container 41 immediately after the engine is started is sucked into the intake passage 2 after the engine is started, and thus is kept in a vacuum state.

The purpose of providing the vacuum vessel 41 having the on-off valve 42 is as follows. If the condensation capacity of the condenser 20 is infinite, the vacuum vessel 41 having the on-off valve 42 is unnecessary. However, in reality, the capacity of the condenser is limited, and the refrigerant pressure is changed from the target value in the middle and low speed region and the middle and low load region to the target value in the high load region as shown in FIG. In order to change the refrigerant pressure with good response, in addition to increasing the rotation speed of the cooling fan 21,
This is because the vacuum vessel 41 is a powerful realistic means for improving the response of the refrigerant pressure to the low pressure side.

The flowchart of FIG.
2 for controlling the opening and closing of the shutter. Here, a certain amount of increase in the rotation speed of the cooling fan 21 is linked to the opening operation of the on-off valve 42.
The calculation of the rotation speed target value of 1 is also shown.

In FIG. 10, at step 41, in addition to the engine speed and the engine torque, the throttle valve opening TVO
Read. Here, FIG. 9 shows a so-called electronic control throttle device in which the throttle valve 31 is driven by a step motor 32 which receives a command from the control device 22 irrespective of an accelerator pedal (not shown). In a gasoline engine equipped with a throttle device,
The target intake air amount and the target equivalence ratio (corresponding to the target air-fuel ratio according to the accelerator opening and the engine speed), and not only the stoichiometric air-fuel ratio but also the air-fuel ratio leaner than the stoichiometric air-fuel ratio is taken as the target air-fuel ratio. ) Is calculated, and a throttle valve opening and a fuel injection pulse width Ti given to a fuel injector (not shown) are calculated so as to obtain the target intake air amount and the target equivalent ratio. Therefore, here, the calculated value of the throttle valve opening is used as the throttle valve opening TVO.
Of course, if the throttle valve is linked to the accelerator pedal, the throttle valve opening detected by the sensor may be used.

In step 42, the throttle valve angular velocity ω, which is the amount of change in the throttle valve opening per unit time, is calculated using the throttle valve opening TVO. this is,
For example, if the calculation cycle in FIG. 10 is Δt, the calculation may be performed by dividing a value obtained by subtracting the previous throttle valve opening from the current throttle valve opening by Δt in the calculation cycle.

In step 43, it is determined whether or not the throttle valve angular velocity ω and the throttle valve opening TVO thus calculated satisfy predetermined conditions. When the throttle valve angular velocity ω and the throttle valve opening TVO satisfy predetermined conditions, the process proceeds to steps 44 and 45 to open the on-off valve 43, and the rotational speed target value of the cooling fan 21 is set to a fixed amount β compared to the first embodiment. Just make it bigger. On the other hand, if at least one of the throttle valve angular velocity ω and the throttle valve opening TVO does not satisfy the predetermined condition, the routine proceeds from step 43 to step 4
Proceeding to steps 6 and 47, the on-off valve 43 is held in the fully closed state, and the rotational speed target value R0 of the cooling fan 21 is calculated with the same value as in the first embodiment.

Here, the predetermined condition is, as shown by the hatched portions in FIGS. 11 and 12, the throttle valve opening TVO.
Is within a predetermined value and the throttle valve angular velocity ω is equal to or more than the predetermined value (that is, at the time of rapid acceleration from a low load). This is a condition that requires a rapid increase in condensation capacity during rapid acceleration from a low load range. In addition to controlling the opening of the pressure regulating valve 14, the on-off valve 42 is opened and the refrigerant pressure is controlled by the vacuum vessel 41. At the same time, the rotational speed of the cooling fan 21 is increased to increase the condensation capacity of the condenser 20 itself.

In practice, it is considered that the conditions under which the sudden increase in the condensing capacity is required may differ depending on the engine operating conditions (engine speed and engine torque) at that time. Multiple maps may be required. Therefore, a plurality of maps for each engine operating condition are prepared in advance, and the following operations are performed instead of steps 43, 44, and 45.

(1) A map corresponding to the engine speed and the engine torque at that time is selected. The plurality of maps prepared in advance are, for example, as shown in FIGS. In the figure, the engine speed is the same 1200 rpm.
Thus, three maps having different engine torques are slightly shifted. In this case, if the current engine speed is 120
If the engine torque is 20 N · m at 0 rpm, FIG.
The foreground map in FIG. 12 is selected.

(2) Follow the instructions in the area to which the throttle valve opening and the throttle valve angular velocity belong at that time. If the area to which the throttle valve opening and the throttle valve angular velocity belong at that time is the lower left area in the foreground maps in FIGS. 11 and 12, the open / close valve is opened and R0
i + β is set to the rotation speed target value R0 of the cooling fan. Here, the R of each area in the foreground map in FIG.
0i is the same value. R0i has different values for different maps, for example, R0j for the second map from the front and R0k for the third map from the front. R0i, R
The relationship of R0i <R0j <R0k is established between 0j and R0k.

The parameters used to determine the predetermined condition are not limited to the combination of the throttle valve opening TVO and the throttle valve angular velocity ω. For example, an intake air amount or a fuel injection amount (fuel injection pulse width Ti) can be used instead of the throttle valve opening (see FIGS. 13 and 14). If the case of FIG. 13 is a third embodiment and the case of FIG.
Also in the case of the two embodiments, a map is selected for each engine operating condition, and in the map, the intake air amount or the fuel injection amount is equal to or less than a predetermined value, and the acceleration of the intake air amount or the fuel injection amount is equal to or more than a predetermined value. One time, while opening the on-off valve 43,
The rotation speed target value of the cooling fan 21 is increased by a certain amount β from the value in the first embodiment.

In the second embodiment, in addition to the opening operation of the on-off valve 43 and the increase in the rotation speed of the cooling fan 21, the electric water heater is provided for improving the response to the decrease in the refrigerant pressure under the above-mentioned predetermined conditions. The pump 13 is temporarily stopped. The reason why the response of the refrigerant pressure is improved by temporarily stopping the electric water pump 13 is as follows.
This is because the operation of the electric water pump 13 increases the pressure downstream of the water pump 13 (therefore, the refrigerant pressure). Therefore, when the water pump 13 is stopped, the refrigerant pressure decreases correspondingly.

The temporary stop of the electric water pump 13 will be specifically described with reference to the flowchart of FIG. FIG. 15 is for controlling the drive of the electric water pump 13 and replaces FIG. 7 of the first embodiment. The same steps as those in FIG. 7 are denoted by the same step numbers, and detailed description is omitted.

Steps different from those in FIG.
At steps 6 and 27, the electric water pump 13 is temporarily stopped. More specifically, when the throttle valve opening TVO and the throttle valve angular velocity ω are both under the predetermined condition in step 25, the process proceeds to step 26, and the elapsed time after the predetermined condition is satisfied is compared with a predetermined value. If the elapsed time since the predetermined condition is satisfied has not reached the predetermined value (if the predetermined time has not elapsed), the process proceeds to step 27, in which the electric water pump 13 is deactivated, and the predetermined condition is satisfied. When the elapsed time after the predetermined time has reached the predetermined value (when the fixed time has elapsed), the electric water pump 13 is returned to the operating state in step 23.

In the third embodiment, step 25 is performed when both the intake air amount and its acceleration are under predetermined conditions, and in the fourth embodiment, step 25 is performed when both the fuel injection amount and its acceleration are under predetermined conditions. It goes without saying that it is replaced at a certain time.

As described above, according to the second, third, and fourth embodiments, the on-off valve 42 is opened and the steam outlet is opened only under predetermined conditions that require a rapid increase in condensation capacity. Since the refrigerant pressure is suddenly reduced by connecting the vapor passage 11 near the part 12 and the vacuum vessel 41, the rotation speed of the cooling fan 21 is also increased to improve the condensation capability of the condenser 20 itself. The refrigerant pressure (the temperature of the peripheral wall of the combustion chamber) can be reduced with good response even at the time of rapid acceleration from a low load, which is a condition that requires a rapid increase in condensation capacity.

Further, if the electric water pump 13 is operating when the predetermined condition is satisfied, the operation of the electric pump 13 is stopped for a certain period of time from the time when the predetermined condition is satisfied. Response can be further improved.

The control system diagram of FIG. 16 is a fifth embodiment, which replaces FIG. 1 of the first embodiment. FIG.
The same reference numerals are given to the same parts as those described above, and the detailed description is omitted.

In the fifth embodiment, the superheater 51 and the turbine 52 are provided in the steam passage 11 downstream of the pressure regulating valve 14 so as to recover the heat energy discarded to the cooling system and the exhaust system of the internal combustion engine. It was made. That is,
When the cooling water which has become the saturated steam by receiving the engine combustion heat in the water jacket 8 is sent to the superheater 51, the saturated steam is further heated by the exhaust heat by the superheater 51, so that part of the exhaust energy is reduced. Absorb. Further, thermal energy is recovered as rotational energy by a turbine 52 that generates rotational force with high-temperature, high-pressure superheated steam that has passed through a superheater 51.

The energy recovery by the turbine 52 will be further described with reference to FIG. In FIG. 17, reference numeral 61 denotes a rotating electric machine connected to the turbine 52. The rotating electric machine 61 basically operates as a generator by the rotational force of the turbine 52, and its output is supplied to the battery 63 as charging power via the inverter 62.

A reduction gear (rotation transmission mechanism) 65 having an electromagnetic clutch 64 is provided between the rotating electric machine 61 and the engine main body 1. The transmission of the rotational force between the motor 52 and the rotating electric machine 61 is enabled. That is, when the clutch 64 is turned off, the torque of the turbine 52 can be used only as a power source for power generation as in the related art, whereas when the clutch 64 is turned on, the torque of the turbine 52 can be used. Is transmitted to the engine body via the reduction gear 65, or power is assisted, or the output of the engine body 1 drives the rotating electric machine 61 to generate electric power using the engine body 1 as a power source. Note that 66
Denotes a vehicle electric system which is operated by battery power from the inverter 62. In the case of a hybrid car, an electric motor or the like as a power source thereof corresponds thereto.

The ON / OFF of the clutch 64 and the transfer of electric power between the rotating electric machine 61 and the battery 63 are also described.
It is controlled by the control device 22 based on the actual battery voltage.

As described above, according to the fifth embodiment, waste heat recovery can be performed in addition to the first embodiment.

[Brief description of the drawings]

FIG. 1 is a control system diagram of a cooling system according to a first embodiment.

FIG. 2 shows refrigerant pressure with respect to engine speed and engine torque,
FIG. 4 is a characteristic diagram of a wall temperature around an engine combustion chamber.

FIG. 3 is a flowchart for explaining calculation of an adjustment valve opening degree.

FIG. 4 is a characteristic diagram of a refrigerant pressure target value.

FIG. 5 is a flowchart for explaining calculation of a rotation speed target value of the cooling fan.

FIG. 6 is a characteristic diagram of a rotation speed target value of the cooling fan.

FIG. 7 is a flowchart for explaining opening / closing control of the electric water pump.

FIG. 8 is a flowchart for explaining control of a shutoff valve.

FIG. 9 is a control system diagram of a cooling system according to a second embodiment.

FIG. 10 is a flowchart for explaining control of an on-off valve and calculation of a rotation speed target value of a cooling fan according to a second embodiment.

FIG. 11 is a table showing the opening and closing characteristics of the on-off valve with respect to the opening degree and angular velocity of the throttle valve according to the second embodiment.

FIG. 12 is a table showing characteristics of a rotation speed target value of a cooling fan with respect to an opening degree and an angular velocity of a throttle valve according to a second embodiment.

FIG. 13 is a table showing the opening / closing characteristics of the on-off valve with respect to the intake air amount and its acceleration in the third embodiment.

FIG. 14 is a table showing the opening and closing characteristics of an on-off valve with respect to a fuel injection amount and an acceleration thereof according to a fourth embodiment.

FIG. 15 is a flowchart for explaining opening / closing control of the electric water pump according to the second embodiment.

FIG. 16 is a control system diagram of a cooling system according to a fifth embodiment.

FIG. 17 is a schematic configuration diagram of a control system according to a fifth embodiment.

FIG. 18 is a characteristic diagram of a wall temperature of a peripheral portion of an engine combustion chamber and a refrigerant pressure with respect to an engine load.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 3 Exhaust passage 8 Water jacket 14 Pressure control valve 20 Condenser 22 Control device 41 Vacuum container 42 On-off valve

Claims (15)

[Claims] 1. A closed cooling path having a portion covering the periphery of an engine combustion chamber and circulating a refrigerant by a pump, a condenser for cooling and liquefying a gas phase refrigerant by heat generated by engine combustion, and Valve means for adjusting the pressure of the refrigerant in the gaseous phase in response thereto; means for driving the pump such that the liquid level of the liquid-phase refrigerant covering the periphery of the engine combustion chamber is kept constant; and An internal combustion engine comprising: means for controlling the command value so as to be a target value. 2. The internal combustion engine according to claim 1, wherein said valve means is provided in the vicinity of a portion from which said gaseous refrigerant flows. 3. The internal combustion engine according to claim 1, wherein the target value is a value which is large in a low load region and is small in a high load region. 4. The internal combustion engine according to claim 3, further comprising a fan for forcibly cooling the condenser, and controlling the rotation speed of the cooling fan to a target value. 5. The apparatus according to claim 1, further comprising means for detecting the refrigerant pressure, wherein the command value is feedback-controlled so that the detected value matches the target value. An internal combustion engine according to claim 1. 6. A vacuum vessel having a normally closed on-off valve in the vicinity of a portion from which the refrigerant in a gaseous phase flows out and upstream of the valve means, and a rapid increase in condensation capacity is required. The internal combustion engine according to any one of claims 1 to 5, wherein the on-off valve is opened under the following conditions. 7. The condition according to claim 6, wherein the condition in which the rapid increase in the condensing capacity is required is in a region where the engine load is equal to or less than a predetermined value and the changing speed of the engine load is equal to or more than a predetermined value. Internal combustion engine. 8. The internal combustion engine according to claim 7, wherein the engine load is a throttle valve opening, an intake air amount, or a fuel injection amount. 9. The internal combustion engine according to claim 7, wherein the condition in which the rapid increase in the condensation capacity is required is set for each engine operating condition. 10. The method according to claim 6, wherein the target value of the rotation speed of the cooling fan is corrected to increase under the condition that the rapid increase of the condensation capacity is required. Internal combustion engine. 11. The pump according to claim 6, wherein when the pump is operating, the operation of the pump is temporarily stopped when a condition that requires a rapid increase in the condensation capacity is satisfied. 11. The internal combustion engine according to any one of items 1 to 10. 12. The internal combustion engine according to claim 1, wherein a relief valve is provided in a passage that bypasses the valve means. 13. When the liquid-phase refrigerant is moved from the cooling path to the reservoir tank when the engine is stopped, and when the inside of the cooling path is evacuated when the engine is started, the refrigerant is returned from the reservoir tank into the cooling path. 13. The internal combustion engine according to claim 1, wherein a negative suction pressure downstream of a throttle valve is used to evacuate the cooling path. 14. A vacuum pump according to claim 6, wherein said vacuum container is evacuated by using a suction negative pressure downstream of a throttle valve.
3. The internal combustion engine according to any one of 2 to 2. 15. A superheater for heating gas-phase refrigerant passing through the valve means with engine exhaust gas, and a turbine for converting heat energy of the gas-phase refrigerant superheated by the superheater into mechanical energy. The internal combustion engine according to any one of claims 1 to 14, characterized in that: