WO2000047886A1

WO2000047886A1 - Method and device for controlling temperature of sucked air

Info

Publication number: WO2000047886A1
Application number: PCT/JP2000/000647
Authority: WO
Inventors: Kazumi Ubukata; Norio Suda
Original assignee: Nippon Thermostat Co., Ltd.
Priority date: 1999-02-12
Filing date: 2000-02-07
Publication date: 2000-08-17
Also published as: TW451027B; JP2000234568A

Abstract

A method of controlling a sucked air temperature in an internal combustion engine, characterized by comprising the steps of varying the opening and closing amount of a hot air valve (3) according to a variation in temperature of the sucked air comprising warm air, outside air, or both of them, maintaining the temperature of the sucked air within a constant range by controlling the hot air-outside air mixing ratio, controlling the hot air-outside air mixing ratio based on a variation of negative pressure in an intake chamber (13) and also based on the load conditions specified from engine control parameters and, in a particular condition, bringing the hot air valve (3) forcibly into an outside air introducing state irrespective of the temperature of the sucked air.

Description

Specification

TECHNICAL FIELD The present invention relates to a method and a device for controlling the temperature of intake air.

The present invention relates to a method and a device for controlling the temperature of intake air in an internal combustion engine. Background art

Of the car engines, carburetor-based engines often suffered icing from late fall to early spring. This phenomenon occurs when the humidity is high and sufficient warm air cannot be obtained, such as on a rainy day. When icing was used, it caused problems with idling or stalling.

In order to reduce such problems, an automatic temperature control air cleaner that uses warm air generated around the exhaust manifold as appropriate intake air is currently used. This automatic temperature control air cleaner (referred to as a conventional device) will be described with reference to FIG. FIG. 5 is a schematic diagram showing a temperature control system equipped with a conventional device.

The conventional device 100 is mounted in an intake system as shown in FIG. The intake air from which dust and the like have been removed by the air cleaner 101 becomes an air-fuel mixture through the carburetor 102, and is sent to the intake manifold 103. The air-fuel mixture sent to the intake manifold 103 is further sent to the engine 107 for combustion. The air-fuel mixture (exhaust) after combustion is sent from the exhaust manifold # 04 to the exhaust system. A hot air cover 105 is provided around the outer periphery of the exhaust manifold 104. When the engine 107 starts, the air in the hot air cover 105 is warmed and heated. This warm air is sent to the conventional device 100 through the warm air passage HW. On the other hand, the other air (hereinafter, referred to as outside air) passes through the engine room and is sent into the conventional device 100 through the outside air passage CW.

Inside the passage main body 100a of the conventional device 100, an outside air intake 100b connected to the outside air passage CW and a warm air intake 100c connected to the warm air passage HW are provided. A swinging plate-shaped hot air valve 100d is disposed between the warm air inlet 100c and the outside air inlet 100b, and the hot air valve 100d swings (see the arrow in FIG. 5). ), The outside air intake 100b and the warm air intake 100c are opened and closed. The ratio of the opening and closing, that is, the opening degree of the hot air valve 100d determines the mixing ratio of warm air and outside air, and determines the temperature of the intake air. Therefore, by controlling the opening of the hot air valve 1OOd, the mixture ratio of warm air and outside air is adjusted, and the temperature of the intake air is controlled. The thermostat 106 controls the opening of the hot air valve 1 OOd. The thermostat 106 is provided in the passage main body 100a, and includes a spring holder 106a and a shaft 106b that move forward and backward. The shaft 106b is mounted on the front of the spring holder 106a, and moves forward and backward together with the spring holder 106a by the expansion and contraction of wax and the action of the spring 106c. Further, the tip of the shaft 106b is connected to the bottom of the hot air valve 100D via a link mechanism. The bottom of the hot air valve 1OOd is pivotally supported from both sides, and swings around the bottom as the shaft advances and retreats.

According to the conventional apparatus 100 described above, the problem that icing (freezing) occurs in the passage of the intake air, particularly in the vicinity of the throttle valve, thereby causing inconvenience such as idling malfunction is avoided.

On the other hand, the following problems have arisen in terms of fuel efficiency. In other words, during normal driving (hereinafter, referred to as partial load operation), especially during low load driving such as idling or partial driving, the throttle valve is in a state where the intake air passage is almost blocked, and The resistance becomes maximum and the bombing loss increases.

In order to reduce this pumping loss, it is necessary to open a throttle valve. However, the opening of the throttle valve is closely related to the vehicle speed. Simply opening the throttle valve increases the engine speed and consequently increases the speed. In other words, it does not eliminate the bombing loss during low load driving. However, if the temperature of the intake air is set to be high, the intake air thermally expands, so that the actual flow rate of the intake air decreases. Then, the throttle valve can be opened, and the throttle valve can be opened even when the vehicle is running at a low load such as idling or partial driving, so that the pumping loss can be reduced.

On the other hand, when the accelerator is fully depressed (hereinafter referred to as full load operation), the throttle valve is in the fully open state, and the intake resistance is minimal. However, during full load operation, a large output is required, so it is necessary to open the throttle valve or reduce the temperature of the intake air, and it is necessary to adjust the temperature of the intake air according to the load condition of the vehicle.

In order to solve the above problems, an improved intake air temperature control device (hereinafter referred to as an improved conventional device) which is an improvement of the conventional device 100 has been developed and disclosed in Japanese Patent Application Laid-Open No. Hei 6-193523. .

This improved conventional device has a configuration similar to that of the conventional device 100, and further includes control means for closing the hot air valve in response to a change in negative pressure in the intake chamber 1. When the throttle valve is fully opened (at the time of full load operation), the negative pressure in the intake chamber becomes a small force. When the negative pressure is detected, the control means forcibly activates the hot air valve regardless of the temperature of the intake air. close. As a result, during full load operation where a large output is required, low-temperature outside air is introduced, and the combustion efficiency is improved.

On the other hand, at the time of the partial load operation, the control means does not operate, and the temperature of the intake air is kept in a certain range as in the conventional device. If this temperature is set to a relatively high temperature, the bombing loss that was large during partial load operation, especially during low load driving, is reduced. As described above, according to the improved conventional device, the fuel efficiency can be improved as compared with the conventional device 100.

In the improved conventional device, the full load operation and the like are specified based only on the negative pressure change in the intake chamber. As a result, there was a problem with the accuracy of the identification, and a substantial improvement in fuel efficiency could not be achieved.

In addition, since only this negative pressure change was used as a specific material, power and external air introduction status could not be created when the vehicle state could be determined based on the negative pressure change, and lacked versatility.

An object of the present invention is to solve the above-mentioned problems by reducing the pumping loss during partial load operation and effectively preventing a decrease in output during full load operation to improve fuel efficiency. With the goal. Disclosure of the invention

As a method for solving the above problem, a method for controlling the temperature of intake air in an internal combustion engine,

The opening / closing amount of the hot air valve is changed according to a change in the temperature of the intake air consisting of warm air, outside air, or both, and the mixing ratio of warm air to outside air is controlled so that the temperature of the intake air is within a certain range. While controlling the mixing ratio between the warm air and the outside air based on the negative pressure change in the intake chamber and also based on the load condition specified from the engine control parameters. And the hot air valve is forcibly brought into the outside air irrespective of the temperature of the intake air.

Further, as a device for solving the above-mentioned problem, a hot-air valve that opens and closes each intake port of warm air and outside air, and an opening and closing amount of the hot air valve to control the amount of intake air composed of the warm air, the outside air, or both of them. An intake air temperature control device for an internal combustion engine having a thermostat for maintaining a temperature in a certain range,

A negative pressure circuit that operates in response to a negative pressure change in the intake chamber, a solenoid that opens and closes the negative pressure circuit to control the operation of the negative pressure circuit, and a load state is specified from engine control parameters, and this load is determined. Load specifying means for causing the solenoid to open and close a negative pressure circuit from a state, and a negative pressure actuator operated by the action of the negative pressure circuit;

The mixing ratio between the warm air and the outside air is controlled based on a change in the negative pressure in the intake chamber and a load state specified from the engine control parameter. Under a specific condition, there is no relation to the temperature of the intake air. The intake air temperature control device is characterized in that the hot air valve is forcibly brought into the outside air introduction state by the operation of the pressure actuator.

By the above means, it is possible to reduce the bombing loss during the partial load operation and prevent the output from decreasing during the full load operation. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a configuration diagram of the intake air temperature control device according to the present embodiment, FIG. 2 is a longitudinal sectional view showing the inside of the passage main body, and FIG. 3 is a diagram of the intake air temperature control device according to the present embodiment. FIG. 4 is a table showing a control pattern according to the intake air temperature control method according to the present embodiment, and FIG. 5 is a temperature control system equipped with a conventional intake air temperature control device. FIG. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be specifically described based on embodiments with reference to the drawings.

FIG. 1 is a configuration diagram of an intake air temperature control device 1 (hereinafter, referred to as a control device 1) according to the present embodiment, and the band-shaped arrows in FIG. 1 indicate flow paths of warm air, outside air, and intake air. Is shown.

At the entrance of the air cleaner 101, a passage body 2 is attached. A passage 23 through which the intake air flows is formed inside the passage body 2, and the passage 23 is forked. One of the two branches is formed with an outside air intake 21 to which the outside air path CW is connected, and the other is formed with a warm air intake 22 to which the warm air path HW is connected. A hot air valve 3 is provided at a location where the outside air inlet 21 and the warm air inlet 22 are connected, and the hot air valve 3 is swingable about the bottom 31 as a fulcrum (see the arrow in FIG. 1). is there.

The hot air valve 3 according to the present embodiment has a plate shape, and opens and closes the outside air inlet 21 and the warm air inlet 22 by the swing. To the bottom 31 of the hot air valve 3, a shaft 41 forming a link mechanism is rotatably connected. The shaft 41 moves forward and backward by the action of the element 43, and the hot air valve 3 swings by the forward and backward movement.

In addition to the shaft 41, an advancing / retracting rod 51 of the negative pressure actuator 5 is connected to the bottom 31 of the hot air valve 3 so as to be rotatable and form a link mechanism. The reciprocating rod 51 is normally in the retracted position (the position on the left side in FIG. 1) due to the operation of the negative pressure actuator 5, and does not interfere with the reciprocating movement of the shaft 41 and affects the swing of the hot air valve 3. Without giving ,. However, when the negative pressure actuator 5 is released and moves to the standing position (moves to the right in FIG. 1), the bottom 31 of the hot air valve 3 is forcibly pushed out. As a result, the hot air valve 3 opens the outside air inlet 21 and completely closes the warm air inlet 22.

The intake air is only the outside air, only the warm air, or a mixture thereof, and the temperature of the intake air is determined by the mixture ratio of the outside air and the warm air. Since the generation of warm air has been described in the related art, a detailed description thereof will be omitted. The greater the percentage of warm air warmed with the start of engine 107 (see Figure 5), the higher the temperature of the intake air. The mixing ratio between the outside air and the warm air is determined by the amount by which the hot air valve 3 opens and closes the outside air inlet 21 and the warm air inlet 22 (hereinafter, referred to as the valve opening / closing amount).

It should be noted that the hot air valve 3 according to the present embodiment has a relationship in which the opening / closing amount is changed by swinging, and if one is opened, the other is closed. Therefore, in the following description, for convenience, the state in which the warm air inlet 22 is closed is referred to, and "open j" means that the warm air inlet 22 is opened from the closed state. Means a movement in a direction to close the outside air intake 21, and “close” means the opposite. A state in which the outside air intake 21 is opened and the warm air intake 22 is completely closed is an “outside air introduction state”. The intake air is sent to the air cleaner 101 through the passage 23 in the passage body 2. The intake air from which dust and the like have been removed by the cleaner 101 passes through the throttle chamber 11 whose flow path diameter is narrowed. A throttle valve 8 is provided in the throttle chamber 11. The amount of rotation of the throttle valve 8 is interlocked with the depression of the accelerator, and rotates from a closed position perpendicular to the flow direction of the intake air to a fully open position parallel thereto.

In the intake chamber 13 extending from the throttle valve 8 to the engine 107 (see FIG. 5), a negative pressure source intake 71 is formed, and the negative pressure source intake 71 and the negative pressure actuator 5 are connected to each other. A negative pressure circuit 7 is formed between the two. During the partial load operation, the throttle valve 8 restricts the flow rate of the intake air, so that the negative pressure in the intake chamber 13 increases. Then, the load state is specified from the change in the negative pressure. As a result, the negative pressure circuit 7 operates, and the negative pressure actuator 5 operates. That is, when the negative pressure actuator 5 is operated, the reciprocating rod 51 moves backward (moves to the left in FIG. 1) against the spring 52, and the interference with the hot air valve 3 is released. As a result, the swing of the hot-air valve 3 is exclusively affected by the thermostat 4.

On the other hand, during full load operation, the throttle valve 8 opens, and the intake resistance decreases according to the opening of the throttle valve 8. Then, the negative pressure in intake chamber 13 decreases. As a result, the load state is specified from the change in the negative pressure, and the negative pressure circuit 7 operates based on the load state, and the operation of the negative pressure actuator 5 is released. As a result, the reciprocating rod 51 moves to the standing position, that is, to the right in FIG. 1, by the action of the spring 52, and the hot air valve 3 is forcibly pushed down to enter the outside air.

The negative pressure circuit 7 is provided with a solenoid 6 composed of a three-port solenoid valve. The solenoid 6 opens and closes the negative pressure circuit 7 and controls the operation of the negative pressure circuit 7. That is, when the solenoid 6 opens the negative pressure circuit 7, the negative pressure change of the intake chamber 13 directly acts on the negative pressure actuator 5 as an operation of the negative pressure circuit 7, and when the negative pressure circuit is closed, The intake chamber 13 side is closed and the negative pressure actuator 5 side is opened to the atmosphere. Normally, solenoid 6 is open. However, when the solenoid 6 negative pressure circuit 7 is closed and opened to the atmosphere, the operation of the negative pressure actuator 5 is forcibly released, and the reciprocating rod 51 is in the standing position by the action of the spring 52, and the hot air / lube 3 is It is forcibly pushed down and enters the outside air introduction state.

The solenoid 6 according to the present embodiment closes the negative pressure circuit 7 under a specific condition, that is, at full load operation. As a premise in this case, the ECU as the load specifying means specifies the load state. Hereinafter, the specification of the load state by the ECU will be described. Engine control parameters (hereinafter referred to as control parameters) are sent to the ECU as information. In the present embodiment, as the control parameters, own vehicle information such as “accelerator opening”, “engine speed”, “engine water temperature”, and “vehicle speed” shown in FIG. 1 are exemplified, but the present invention is not limited to this example. Instead, other information may be used as long as it is sufficient to specify the load state. From these control parameters, the ECU determines the negative value of engine 107 (see Fig. 5). Identify the loading status. Then, when it is specified that the operation is at full load operation, an electric signal is sent to the solenoid 6 to close the negative pressure circuit 7. By the way, when it is determined that the vehicle is operating at full load, for example, the vehicle speed is `` low speed J '' despite the accelerator opening force being `` open, '' Identify that it is at full load operation.

That is, the load state is specified from the negative pressure change in the intake chamber 113 and the control parameter, and the mixing ratio between the warm air and the outside air is controlled based on the load state. Further, for example, during the full load operation as in the present embodiment, the hot air valve 3 is forcibly brought into the outside air introduction state by the operation of the negative pressure actuator 5 irrespective of the temperature of the intake air.

The above is the outline of the control device 1 according to the present embodiment. Next, the specific structure of the thermostat 4 for moving the shaft 41 forward and backward, and the connection between the forward and backward rods 51 and the shaft 41 and the bottom 31 of the hot air valve will be described with reference to FIG. FIG. 2 is a longitudinal sectional view showing the inside of the passage body 2.

First, the structure of the thermostat 4 will be described.

The spring holder 42 has a front inner hole 42b and a rear inner hole 42c formed on both front and rear sides of the center inner wall 42d, and the front end of the front inner hole 42b and the rear end of the rear inner hole 42c are open. Te shiru. The base end 41a of the shaft 41 is housed in the front inner hole 42b, and the piston 43a of the element 43 is slidably fitted in the rear inner hole 42c.

The spring holder 42 and the element 43 are supported by front and rear support members 12a and 12b, and are positioned vertically. Incidentally, the spring holder 42 is supported by the front support member 12a so as to be able to advance and retreat in the front-rear direction, and the element 43 is fixed by the rear support member 12b.

A flange 42a is formed on the outer periphery of the rear end of the spring holder 42, and a spring 44 is provided between the flange 42a and the front support member 12a. This spring 4

4 always biases the spring holder 42 rearward.

A flange-shaped base end 41a formed at the rear end of the shaft 41 has its outer periphery slidably inscribed in the front inner hole 42b of the spring holder 42. A coil spring 41b is provided between the base end 41a and the central inner wall 42d, and constantly urges the shaft 41 forward. The opening formed at the front end of the front inner hole 42b is bent toward the center to prevent the base end 41a from coming off. On the other hand, a rod 43b protrudes and retracts from the front end (the front side in FIG. 2) of the piston portion 43a housed in the rear inner hole 42c of the spring holder 42. The rod 43b is raised and lowered by the action of wax and an elastic member (not shown) housed in the element 43. That is, when a change in the temperature of the intake air propagates as heat to the wax via the temperature sensing unit 43c, the wax expands and contracts and interferes with the rod 43b. This interference is balanced with the elastic member, and the rod 43b projects when inflated, and sinks when contracted.

The above is the structure of the thermostat 4. Next, the connection relationship between the shaft 41 and the reciprocating rod 51 and the bottom 31 of the hot water valve 3 will be described. The bottom 31 of the hot air valve 3 is pivotally supported on both sides by the passage body 2, and the hot air valve 3 swings around the bottom 31. An upper connecting portion 31a and a lower connecting portion 31b are formed at upper and lower positions with the bottom portion 31 therebetween. The top end of the rod 51 is rotatably connected to the upper connecting part 31a via a pin 33a, and the end of the shaft 41 is rotatably connected to the lower connecting part 31b via a pin 33b. Be linked. The reciprocating directions of the reciprocating rod 51 and the shaft 41 are parallel to each other.

The shaft 41 can allow the pin 33b to move up and down due to the swing of the hot air valve 3 when moving forward and backward. On the other hand, a slit 51a is formed at the distal end of the advancing / retracting rod 51 of the negative pressure actuator 5 (see FIG. 1), and a pin 33a is movable in the slit 51a. Accordingly, when the negative pressure actuator 5 (see FIG. 1) is actuated and the reciprocating rod 51 is in the retracted position, the pin 33a automatically moves through the slit 51a of the reciprocating rod 51 as the hot air valve 3 swings. Move for free. Therefore, the reciprocating rod 51 does not interfere with the swing of the hot air valve 3.

However, when the operation of the negative pressure actuator 5 (see FIG. 1) is released and the reciprocating rod 51 is in the standing position, the swing of the hot air valve 3 is affected. That is, when the operation of the negative pressure actuator 5 (see FIG. 1) causes the advance / retreat rod 51 to move forward (moving backward in FIG. 2), the slit 51 a is hooked on the pin 33. As a result, the connecting portion 31a is forcibly pushed out, and the hot air valve 3 is closed. In addition, the shaft 41 and the spring holder 42 are pulled by this extrusion. As a result, the spring holder 42 and the rod 43b projecting from the piston portion 43a are temporarily separated.

The operation of the control device 1 will be described with reference to FIG. FIG. 3 is a schematic sectional view showing the operation of the control device 1. FIG. 3 (a) shows a state immediately after the engine is started, and FIG. 3 (b) shows a state in which the hot air valve 3 FIG. 3 (c) shows a state where the air is oscillating and the outside air is introduced. As a result, the hot air valve 3 is fully opened in FIG. 4A, the hot air valve 3 is opened in response to the temperature of the intake air in FIG. 4B, and the hot air valve 3 is closed in FIG. ing. In addition, the band-shaped arrows in the figure indicate the flow of outside air, warm air, or intake air, and the normal arrows indicate the swing direction of the hot-air valve 3 or the retreating direction of the reciprocating rod 51.

When the temperature of the intake air rises from the state shown in FIG. 3A, the amount of heat corresponding to the temperature change propagates to the internal wax via the temperature sensing unit 43c, and the wax expands due to the propagation, and the rod 43b projects. (See FIG. 2B). As a result, the spring holder 42 moves forward according to the amount of protrusion, and the shaft 41 moves forward with this movement. Since the tip of the shaft 41 is connected to the lower connecting portion 31b of the hot air valve 3, the forward movement causes the upper end 32h of the hot air valve 3 to tilt. As a result, the inflow of outside air increases, and conversely, the inflow of warm air decreases and the temperature decreases. Conversely, if the temperature of the intake air is too low, the shaft 41 of the thermostat 4 is retracted, and the upper end 32h of the hot air valve 3 rises. As a result, the inflow of outside air decreases, the inflow of warm air increases, and the temperature rises. By the above operation, the temperature of the intake air is kept in a certain range. In the above operation state, the negative pressure actuator 5 (see FIG. 1) is always operated, and the advance / retreat rod 51 is at the retracted position. However, when the operation of the negative pressure actuator 5 (see Fig. 1) is released, the retraction rod 51 is in the standing position as shown in Fig. 3 (c), forcibly entering the outside air, and the intake air Is all open air.

A control method using the operation of the control device 1 according to the present embodiment and a specific control pattern will be described with reference to FIG. FIG. 4 is a table showing a control pattern by the control method according to the present embodiment.

During the partial load operation, it is necessary to suppress the substantial flow rate of the intake air. Therefore, it is usually necessary that the throttle valve 8 restricts the flow of the intake air in the throttle chamber 11. In particular, during idling or partial, the throttle valve 8 is closed, so that the intake resistance becomes maximum and the bombing loss becomes maximum.

However, if the control device 1 is provided as in the present embodiment, the thermostat 4 keeps the temperature of the intake air at a higher temperature, so that the throttle valve 8 is opened and the flow rate of the intake air is substantially reduced. Can be restricted to As a result, the intake resistance can be reduced, and the pumping loss is reduced. More specifically, when the temperature of the intake air rises and is kept within a certain range, the volume of the intake air expands and the density decreases. Then, even if the opening of the throttle valve 8 is increased, the flow rate of the intake air sent into the engine 107 is substantially restricted. As a result, the intake resistance decreases and the pumping loss decreases.

Originally, it is desirable that the lower the intake air temperature, the higher the combustion efficiency. Therefore, the intake air is set to an appropriate temperature (target temperature) determined by comparing, for example, the occurrence of bombing loss and the combustion efficiency, and is stabilized within a certain range based on the target temperature. The setting of the target temperature is performed by selecting the thermal expansion and contraction rates of the wax in the thermostat 4 and the elastic moduli of the coil spring 41b and the spring 44. This is because the opening / closing amount of the hot air valve 3 corresponding to the temperature of the intake air is determined by selecting the thermal expansion and shrinkage of the wax in the thermostat 4.

The above control pattern, that is, the control pattern at the time of partial load operation, is shown by the A pattern and the B pattern in FIG. That is, the pattern A corresponds to FIG. 3 (a), and indicates the state immediately after the engine is started. That is, in this state, the hot air valve 3 is closed by the control device 1, and only the warm air is used as the intake air. Therefore, the temperature of the intake air is a rising temperature that has not reached the target temperature. Further, in this case, the opening of the throttle valve 8 needs to be in accordance with the temperature rising characteristic of the intake air, so that the intake resistance also corresponds to this opening.

When the temperature of the intake air rises from this state, the thermostat 4 is activated to keep the temperature of the intake air within a certain range based on the target temperature (FIG. 3 (b)). This control state is indicated by the B button. In the B pattern, the throttle valve 8 can be opened due to the expansion of the volume accompanying the rise in the temperature of the intake air. That is, in the B pattern, the throttle valve 8 is opened to reduce the intake resistance, and the bombing loss is reduced so as to cope with the partial load operation. The above is the control method at the time of ordinary traveling (during partial load operation). If the running state changes during full-load operation such as climbing a hill or sudden acceleration from this normal traveling, if the temperature of the intake air is still the set temperature, climbing hill, sudden acceleration, etc. (During full load operation). Therefore, in order to reduce this problem, at the time of full load operation, the negative pressure actuator 5 (see FIG. 1) is operated to open the hot air valve 3, and all the intake air is outside air. As a result, the temperature of the intake air drops instantaneously, and the combustion efficiency is improved, and a state can be accommodated during full load operation.

The control pattern described above, that is, the control pattern at the time of full load operation, is shown by the C and D patterns in FIG. This control pattern corresponds to FIG. 3 (c).

Pattern C is for full load operation when the engine is started. In this case, the negative pressure actuator 5 in the control device 1 is released, and the hot air valve 3 is forcibly brought into the outside air introducing state. As a result, combustion efficiency is improved, and a decrease in output is prevented. In the pattern C, the throttle valve 8 is fully opened, and the intake resistance is a resistance corresponding to the opening of the throttle valve 8.

After the warm air has been sufficiently warmed by driving the engine 107 (see Fig. 5), the D pattern suddenly changes to full load operation. Also in this case, the negative pressure actuator 5 is released, and the hot air valve 3 is forcibly brought into the outside air introducing state. As a result, the combustion efficiency is improved, and a decrease in output is prevented. Also in this case, the throttle valve 8 is fully opened, and the intake resistance is the resistance corresponding to the opening degree I of the throttle valve 8.

In the present embodiment, the full load operation is described as an example of the “certain specific condition”. However, “certain conditions” are not limited to full load operation, and include a wide range of situations where large output is required. In addition, the load state is specified not only by the negative pressure change in the intake chamber 13 but also by a load specifying means based on the control parameter. As a result, it is possible to more accurately specify the load state.

ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the bombing loss at the time of a partial load driving | operation can be reduced, and a specific condition, for example, the fall of the output at the time of full load driving | operation can be prevented effectively. As a result, it is possible to improve fuel efficiency.

Claims

The scope of the claims

1. A method for controlling the temperature of intake air in an internal combustion engine,

The opening / closing amount of the hot air valve is changed according to a change in the temperature of the intake air consisting of warm air, outside air, or both, and the mixing ratio of warm air to outside air is controlled so that the temperature of the intake air is within a certain range. While controlling the mixing ratio between the warm air and the outside air based on the negative pressure change in the intake chamber and also based on the load condition specified from the engine control parameters. A method for controlling the temperature of the intake air, wherein the hot air valve is forcibly brought into the outside air state irrespective of the temperature of the intake air.

2.A hot air valve that opens and closes each intake port of warm air and outside air, and a thermostat that controls the opening and closing amount of the hot air valve to keep the temperature of the intake air consisting of the warm air, the outside air, or both within a certain range. An intake air temperature control device for an internal combustion engine having

A negative pressure circuit that operates in response to a change in negative pressure in the intake chamber, a solenoid that opens and closes the negative pressure circuit, controls the operation of the negative pressure circuit, and specifies a load state from engine control parameters. Load specifying means for causing the solenoid to open and close a negative pressure circuit from a load state, and a negative pressure actuator operated by the action of the negative pressure circuit,

The mixing ratio between the warm air and the outside air is controlled based on a change in the negative pressure in the intake chamber and a load state specified from the engine control parameter, and under a specific condition, the mixture ratio is independent of the temperature of the intake air. An intake air temperature control device characterized in that the hot air valve is forcibly brought into an outside air introduction state by operation of a negative pressure actuator.