JP2002070664A - Internal combustion engine having combustion heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine having a combustion heater capable of keeping a good combustion state regardless of the engine operation or stoppage. SOLUTION: This internal combustion engine has an air feeding passage 71 for introducing the air for combustion into a combustion heater 7 from an intake passage 4 in the upstream of an intake throttle valve 14, a combustion gas discharge passage 73 for introducing the combustion gas discharged in conjunction with the combustion of a gaseous mixture into the intake passage 4 in the downstream of the intake throttle valve 14 from the combustion heater 7, and a pressure regulation means 53 for regulating the pressure in the air feeding passage 71 and the pressure in the combustion gas discharge passage 73.

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 having a combustion heater, and more particularly, to a technique for stabilizing a combustion state of the combustion heater.

[0002]

2. Description of the Related Art The warming of the engine body during cold weather,
2. Description of the Related Art There is known an internal combustion engine provided with a combustion heater for the purpose of improving the performance of heating a vehicle interior. In this type of internal combustion engine,
After the air required for combustion in the combustion type heater is taken in from the intake passage of the internal combustion engine and combusted with engine fuel, the heat medium (combustion gas generated during the combustion) is used as a heat medium that becomes an engine-related element by using heat of the combustion gas. For example, cooling water) is heated. The heated heat medium is supplied into the engine body or the like to promote warm air of the engine body. On the other hand, the combustion gas generated by the combustion in the combustion type heater is returned to the intake passage of the internal combustion engine and supplied to the engine main body. After the intake air is heated, it flows down the exhaust passage and is discharged to the atmosphere.

More specifically, a combustion type heater is
An air supply passage, which is provided in an intake system of an internal combustion engine and is connected to an intake passage to take in air required for combustion into a combustion type heater, and a combustion gas connected to the intake passage for combustion in a combustion type heater. A combustion gas discharge passage discharging to the intake passage;
have. That is, a path is formed between the intake passage of the internal combustion engine and the combustion type heater, such as an intake passage → an air supply passage → a combustion type heater → a combustion gas discharge passage → an intake passage.

On the other hand, the intake passage of the internal combustion engine is provided with an intake throttle valve for adjusting the output of the engine body by adjusting the amount of air (intake amount) flowing through the intake passage and supplied to the engine body. . The intake throttle valve is usually provided downstream (closer to the internal combustion engine) from the connection between the intake passage and the air supply passage and the connection between the intake passage and the combustion gas discharge passage. Depending on the gender, it may be arranged between the connection points depending on the case.

[0005]

As is well known, the pressure in the intake passage of an internal combustion engine fluctuates greatly depending on the operating state of the engine body. In particular, in those equipped with an intake throttle valve between each connection point, the opening and closing operation of the intake throttle valve,
A large differential pressure occurs between the intake throttle valve upstream and the intake throttle valve downstream. Therefore, this differential pressure causes air to flow into the combustion type heater in an amount different from the amount of air to be supplied to the combustion type heater. On the other hand, the combustion type heater is provided with a rotating fan for adjusting the air amount,
As described above, if an amount of air that is different from the amount of air to be supplied is supplied to the combustion heater, the combustion state of the combustion heater becomes unstable, and ignition becomes difficult. A phenomenon was seen.

[0006] Further, the combustion type heater is sometimes used when the engine is stopped. However, when the engine is stopped, the air filled in the intake passage stays in the intake passage. Therefore, in the combustion type heater in which the air supply passage and the combustion gas discharge passage are provided in the intake passage, the air is discharged to the intake passage. The burned gas may flow around to the air supply passage.
For this reason, the combustion gas is mixed into the air supplied to the combustion type heater, and the amount of air (the amount of oxygen) required for combustion decreases, and the combustion state becomes unstable. Also, soot and the like may be generated together with the combustion gas.

When the operating time of the combustion type heater is prolonged when the engine is stopped, the air filled in the intake passage is consumed by the combustion in the combustion type heater, and the intake passage is filled with the combustion gas instead. . Therefore, it was difficult to secure the air required for combustion, and the combustion heater could not be operated continuously.

The present invention has been made in consideration of the above points, and has as its object to provide an internal combustion engine having a combustion heater capable of maintaining a good combustion state regardless of whether the engine is operating or stopped. .

[0009]

Means for Solving the Problems In order to solve the above technical problems, the present invention employs the following means. That is, it is provided in an internal combustion engine provided with an intake throttle valve for restricting intake air flowing through an intake passage, and air for combustion is introduced and mixed with fuel to generate an air-fuel mixture, which is discharged as the air-fuel mixture is burned. An internal combustion engine having a combustion heater capable of utilizing heat of a combustion gas, comprising: an air supply passage for taking combustion air from an intake passage upstream of an intake throttle valve into the combustion heater; It has a combustion gas discharge passage for allowing the discharged combustion gas to flow from the combustion type heater into the intake passage downstream of the intake throttle valve, and pressure adjusting means for adjusting the pressure in the air supply passage and the pressure in the combustion gas discharge passage. It is characterized by the following.

Since the internal combustion engine having the combustion heater configured as described above has pressure adjusting means for adjusting the pressure of the air supply passage and the pressure of the combustion gas discharge passage,
For example, in a situation where the pressure in the combustion gas discharge passage is lower than the pressure in the air supply passage, the pressure in the air supply passage is reduced, or the pressure in the combustion gas discharge passage is increased, and the combustion in the air supply passage is reduced. Unnecessary inflow of air into the combustion type heater due to the pressure difference between the gas discharge passage and the gas discharge passage is suppressed. Therefore, the flow rate and the flow velocity of the air supplied to the combustion heater are stabilized, and the combustion state in the combustion heater is improved.

The heat obtained by the combustion of the air-fuel mixture is preferably used mainly for raising the temperature of components related to the engine. The engine-related elements include a heat medium such as engine cooling water, an engine body, an intake passage provided in the engine body, an exhaust purification device for purifying harmful substances discharged from the engine body, and heating using heat of the internal combustion engine. A device and the like can be exemplified.

Further, the pressure adjusting means according to the present invention is interposed between the air supply passage and the combustion gas discharge passage, and adjusts the pressure so that the pressure of the air supply passage and the pressure of the combustion gas discharge passage are close to each other. It is desirable. Here, that the pressure adjusting means is interposed between the air supply passage and the combustion gas discharge passage means that the pressure adjustment means is based on a relative pressure relationship between the pressure of the air supply passage and the pressure of the combustion gas discharge passage. The pressure adjustment method that can be adopted is not particularly limited. To make the pressure of the air supply passage close to the pressure of the combustion gas discharge passage means to make the pressure of the combustion gas discharge passage close to the pressure of the air supply passage, or the pressure of the air supply passage to the pressure of the combustion gas discharge passage. Is to get closer. Further, both the pressure of the air supply passage and the pressure of the combustion gas discharge passage may be adjusted so as to approach each other.

In this case, since the pressure of the air supply passage and the pressure of the combustion gas discharge passage are substantially the same, the amount of air supplied to the combustion heater and the combustion gas discharged from the combustion gas discharge passage Is substantially equal to the emission amount. Therefore, the amount of air supplied to the combustion type heater and the flow rate of air or combustion gas flowing in the combustion type heater are stabilized, and a favorable combustion state can be obtained.

A pressure control valve is provided in at least one of the air supply passage and the combustion gas discharge passage, and the pressure control means is provided in accordance with a differential pressure between the pressure in the air supply passage and the pressure in the combustion gas discharge passage. Thus, the pressure control valve may be controlled. With this configuration, the pressure of the air supply passage and the pressure of the combustion gas discharge passage can be made close to each other with a relatively simple structure.

The structure of the pressure control valve is not particularly limited, such as a structure in which the pressure is reduced when the valve is closed and a structure in which the pressure is reduced when the valve is opened. In addition, as a pressure control valve that reduces the pressure when the valve is closed, a butterfly valve that narrows the flow path to reduce the pressure can be exemplified. Examples of the pressure control valve that reduces the pressure when the valve is opened include a pressure reducing valve that releases the pressure to the outside and reduces the pressure. Note that these various pressure control valves may be provided in both the air supply passage and the combustion gas discharge passage.

In the internal combustion engine according to the present invention, an exhaust passage for discharging exhaust discharged from the internal combustion engine to the outside of the engine and an intake passage downstream of the intake throttle valve bypass the cylinders of the internal combustion engine. The exhaust gas recirculation passage may be configured to communicate with the exhaust gas.

That is, the exhaust gas passage is formed by bypassing the intake passage and the exhaust passage. In the internal combustion engine configured as described above, the combustion gas is quickly exhausted even in a state where the combustion gas easily stays in the intake passage, such as when the engine is stopped or the engine is running at a low speed. Therefore, it is possible to improve the instability of the combustion state caused by the inflow of the combustion gas. Further, since the combustion gas does not stay in the intake passage, the combustion type heater can be continuously used even when the engine is stopped.

The internal combustion engine according to the present invention may include an intake throttle valve control means for closing the intake throttle valve when the combustion type heater is operating. Further, it is desirable that the intake throttle valve control means closes the intake throttle valve at least when the engine of the internal combustion engine stops.

In the internal combustion engine having the combustion heater configured as described above, by closing the intake throttle valve,
The combustion gas can be reliably prevented from entering the air supply passage. Therefore, it is possible to improve the instability of the combustion state caused by the inflow of the combustion gas. When closing the intake throttle valve, the valve is closed using an electric element such as an electrically driven actuator, or the valve is closed using a mechanical element such as a spring. The mechanism and structure applied when closing the intake throttle valve are not limited.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which an internal combustion engine having a combustion heater according to the present invention is applied to an internal combustion engine mounted on a vehicle will be described below with reference to the drawings.

The internal combustion engine 1 according to the present embodiment has an engine body 3 having a water jacket (not shown) filled with engine cooling water, and air required for combustion with respect to a plurality of cylinders 3a of the engine body 3. , A fuel supply device 5 that injects engine fuel into air supplied into each cylinder 3a through the intake passage 4 to form a mixture, and discharges from each cylinder 3a with the combustion of the mixture. An exhaust gas recirculation device (EGR device) that suppresses generation of nitrogen oxides during engine operation by recirculating exhaust gas from the exhaust gas passage 6 to the intake passage 4 and discharging the exhaust gas to the atmosphere. ) 8
And

Further, a combustion type heater 7 for combusting combustion air together with the engine fuel separately from the internal combustion engine 1 and raising the temperature of the engine-related elements by utilizing the heat of the combustion gas generated at that time; The vehicle includes a heater core 10 serving as a vehicle interior heating device for increasing the indoor temperature of a vehicle on which an internal combustion engine is mounted, and an ECU 11 for controlling the entire internal combustion engine. Hereinafter, each configuration will be described in detail.

The intake passage 4 is terminated by an intake port (not shown) of the engine body 3 with an air cleaner 13 for filtering outside air as a start end, and an intake throttle valve 14 for adjusting the output of the engine body 3 is provided in the middle of the passage. ing. Also,
The intake passage 4 is connected to the intake passage 4 upstream of the intake throttle valve 14 and takes in air for combustion into the combustion type heater 7, and the intake passage 4 is connected to the intake passage 4 downstream of the intake throttle valve 14 for combustion. The combustion gas accompanying the combustion in the heater 7 is again
A combustion gas discharge passage 73 that flows into the intake passage 4. The air supply passage 71 and the combustion gas discharge passage 73
And the combustion type heater 7 is provided so as to connect

The combustion type heater 7 mixes the engine fuel with the air taken in from the intake passage 4 and burns the mixture. Then, the combustion gas accompanying the combustion flows into the intake passage 4 to be supplied to the engine body 3. Temperature (air intake) can be raised. The engine cooling water is guided to the combustion type heater 7, and the engine cooling water heated by the combustion in the combustion type heater 7 is sent to the heater core 10, the engine main body 3, and other places where the temperature needs to be raised. Then, the temperature of the required portion is raised. (In the drawing, only the heater core 10 and the engine main body 3 are shown as the portions requiring the temperature increase).

The internal combustion engine 1 is provided with a cooling water circulation passage W so that the engine cooling water heated by the combustion type heater 7 can be sent to the above-mentioned required temperature rising point. In the internal combustion engine 1 according to the present embodiment, the engine cooling water is illustrated as the heat medium to raise the temperature of the portion that needs to be heated. Oil or the like may be used.

A cooling water circulation passage W1 connects the engine body 3 and the combustion type heater 7 and guides the engine cooling water from the water jacket of the engine body 3 to the combustion type heater 7;
The engine cooling water heated by the combustion heater 7 is supplied to the heater core 1.
A cooling water discharge passage W2 for leading to zero and a cooling water discharge passage W3 for returning the engine cooling water coming out of the heater core 10 to the water jacket of the engine body 3 are provided. Further, an electric water pump 50 is provided in the cooling water introduction passage W1, and the engine water is circulated in the cooling water circulation passage W by operating the electric water pump 50. The structure of the combustion heater 7 will be described later in detail.

The exhaust passage 7 starts at an exhaust port (not shown) of the engine body 3 and ends at a muffler (not shown). Between the exhaust port and the muffler, a catalytic converter 6a as an exhaust gas purifier is provided. ing. The catalyst contained in the catalytic converter 6a may be a selective reduction type NOx catalyst, a storage reduction type NOx catalyst, a DPF carrying an oxidation catalyst, or the like.

The EGR device 8 connects the intake passage 4 downstream of the intake throttle valve and the exhaust passage 6 upstream of the catalytic converter 6a, bypasses the cylinder 3a of the engine body 3, and communicates therewith, and flows through the exhaust passage 6. An EGR passage 8b that guides a part of the exhaust gas to the intake passage 4 and an EGR valve 8a that adjusts a flow rate of the exhaust gas flowing through the EGR passage 8b. Note that E
The GR valve 8a is controlled by the ECU 11, and is opened and closed at an appropriate timing.

The combustion supply device 5 supplies fuel to the fuel injection nozzles 5a provided in each cylinder 3a, a fuel distribution pipe 5b for supplying fuel to the fuel injection nozzles 5a, and a fuel distribution pipe 5b. The fuel injection nozzle 5a is opened for a predetermined time based on fuel injection control by the ECU 11 described later, and fuel is injected into each cylinder 3a at an appropriate timing. Each of the above-described components is merely an embodiment of the internal combustion engine of the present invention, and details thereof may be changed as appropriate in accordance with specifications of the internal combustion engine.

Next, the structure of the combustion type heater 7 will be described in detail with reference to FIG. The combustion type heater 7 has a heater internal cooling water passage 37 which is connected to the cooling water introduction passage W1 and the cooling water discharge passage W2 and becomes a part of the cooling water circulation passage W therein.

The heater internal cooling water passage 37 has a cooling water inlet 37a connected to the cooling water inlet W1 and a cooling water outlet 37b connected to the cooling water outlet W2. 7 is formed so as to circulate around the combustion chamber 48.

The combustion chamber 48 includes a combustion cylinder 40 as a combustion source for generating the flame F, and a cup-shaped partition wall 41 covering the combustion cylinder 40 and preventing the flame F from leaking to the outside. Then, by covering the combustion cylinder 40 with a partition wall 41,
A combustion chamber 48 is defined within partition 41. On the other hand, the partition 4
1 is also covered by the outer wall 43 of the combustion type heater 7.

An annular gap is provided between the partition wall 41 and the outer wall 43, and this gap functions as the heater internal cooling water passage 37. The engine coolant receives heat from the combustion chamber 48 while the engine coolant flows in the heater internal coolant passage 37. That is, the engine cooling water exchanges heat with the hot combustion gas in the combustion chamber 48 to increase the temperature.

Further, the combustion chamber 48 has an air supply port 62 for taking in combustion air into the combustion chamber 48 and a combustion gas discharge port 6 for discharging combustion gas from the combustion chamber 48.
And 3. The air supply port 62 is connected to the combustion chamber 4.
In FIG. 8, the flame F is located on the side opposite to the side where the flame F exits from the combustion tube 40, and the combustion gas discharge port 63 is provided in the combustion chamber 48 near the base end of the combustion tube 40.

Each of the air supply port 62 and the combustion gas discharge port 63 communicates with the intake passage 4.
That is, the air supply port 62 communicates with the intake passage 4 via the air supply passage 71 that supplies combustion air from the intake passage 4 to the combustion type heater 7, and the combustion gas discharge port 63 supplies the combustion gas to the combustion type heater 7. It communicates with the intake passage 4 via a combustion gas discharge passage 73 that is discharged from the heater 7 to the intake passage 4.
The connection point C1 between the air supply pipe 71 and the intake passage 4
And connection point C between combustion gas discharge passage 73 and intake passage 4
In 2, the connection point C2 is located downstream of C1.

On the other hand, the combustion cylinder 40 is provided with a fuel introduction passage 88 for introducing fuel from outside. The fuel introduction passage 88 is connected to the fuel pump 89 and receives the pump pressure of the fuel pump 89 from the fuel introduction passage 88 to the combustion cylinder 4.
Fuel is discharged to zero. Further, the combustion cylinder 40 has a glow plug (not shown) that ignites the fuel supplied by the fuel introduction passage 88.

On the outer wall 43 of the combustion type heater 7, a housing 93 containing a rotary fan 90 for blowing air having a motor 92 as a driving source is provided on the side of the combustion cylinder 40 opposite to the side where the flame F is emitted. It is attached.

The housing 93 has an air intake 95 for taking in air from the outside.
Is connected to the air supply passage 71. The housing 93 has an internal space S communicating with the air supply port 62. Therefore, the air supply port 62 is indirectly connected to the air supply passage 71 via the internal space S.

Then, the rotating fan 90 is driven by the motor 92.
Is rotated, air is introduced into the housing 93 from the intake passage 4 via the air supply passage 71. The air guided to the housing 93 is supplied from the air supply port 62 to the combustion cylinder 40 as combustion air through the internal space S.

Then, the combustion gas after the fuel is burned by the combustion air is introduced into the intake passage 4 from the combustion heater 7 via the combustion gas discharge passage 73. The amount of combustion gas introduced into the intake passage 4, that is, the amount of air introduced into the combustion tube 40 is determined by the number of rotations of the rotary fan 90.

That is, as the fan rotation speed increases, the air volume increases, and the amount of air proportional to the fan rotation speed is increased.
After the combustion, the gas becomes combustion gas and is discharged from the combustion heater 7. The rotation speed of the rotating fan 90 is determined by ECU
11 by controlling the motor 92.

On the other hand, the ECU 11, which controls the motor and the fuel pump 89, etc., includes a central processing controller CPU, a read-only memory ROM, a random access memory RAM, an input interface circuit, an output interface It is composed of circuits and the like.

Various sensors are connected to the input interface circuit via electric wiring, and the output interface circuit includes an EGR valve 8a, an electric water pump 50, a glow plug of a combustion cylinder 40, a fuel pump 8
9, the motor 92 and the like are connected via electric wiring.

The sensors connected to the input interface circuit include an air flow meter attached to the intake passage 4, a catalyst temperature sensor attached to the catalytic converter 6a, a water temperature sensor for detecting the temperature of cooling water contained in the water jacket, and an accelerator. An accelerator position sensor, an ignition switch, a starter switch, and the like attached to a pedal or an accelerator lever that operates in conjunction with an accelerator pedal can be exemplified. These sensors output an electric signal corresponding to the detected value, and
Send to U11. In addition, illustration of these various sensors is omitted.

The ECU 11 determines the operating state of the internal combustion engine 1 based on the output signal values of the various sensors described above. Then, the fuel injection control and the like are performed based on the determination result, and the control of the combustion heater 7 is performed.

The control of the combustion type heater 7 by the ECU 11 is as follows. First, by rotating the rotary fan 90, a part of the intake air flowing through the intake passage 4 is transferred through the air supply passage 71 to the combustion cylinder 40 of the combustion heater 7.
Introduce inside. Further, the fuel pump 89 is operated to suck up fuel in a fuel tank (not shown) and discharge the fuel from the fuel introduction passage 88 to the combustion cylinder 40. Further, by operating the electric water pump 50, the engine cooling water of the internal combustion engine 1 is pumped to the heater internal cooling water passage 37 of the combustion type heater 7.

In addition, the glow plug is actuated to ignite a mixture of intake air supplied to the combustion cylinder 40 by the rotary fan 90 and fuel supplied to the combustion cylinder 40 from the fuel introduction passage 88. A flame F is generated therein to start combustion.

The high-temperature combustion gas generated by the combustion flows down the combustion gas discharge passage 73 on the airflow generated by the rotation of the rotary fan 90 and is discharged to the intake passage 4. Then, the air is supplied to the engine main body 3 together with the air required for combustion in the engine main body 3, and is discharged to the atmosphere via the exhaust passage 6.

On the other hand, the engine cooling water pressure-fed from the water jacket to the heater internal cooling water passage 37 of the combustion type heater 7 via the cooling water introduction passage W1 by the electric water pump 50 is supplied to the heater internal cooling water passage 37. Flows around the entire outer surface of the partition wall 41, during which the heat of the combustion gas is absorbed and the temperature rises. In other words, heat exchange between the engine cooling water and the combustion gas is performed in the entire area of the heater internal cooling water passage 37.

The engine cooling water having absorbed the heat of the combustion gas is introduced into the heater core 10 from the heater internal cooling water passage 37 through the cooling water discharge passage W2, and
The engine cooling water coming out from 0 is discharged to the cooling water discharge passage W3 and returns to the water jacket of the engine body 3 (see the broken line arrow in FIG. 2 and the broken line in FIG. 1). The heater core 10
In, a part of the heat stored in the engine cooling water is exchanged with the air for heating, and the temperature of the air for heating rises. As a result, warm air is generated in the vehicle cabin.

As described above, the engine cooling water which has been heated by the combustion type heater 7 and has become high heat flows to the water jacket of the engine body 3 and the room heater 10, and as a result, the warming-up of the internal combustion engine and the startability are improved. And heating performance of the vehicle interior.

By the way, as described above, the intake throttle valve 14 is disposed between the first connection point C1 and the second connection point C2 because of the mountability on a vehicle like the internal combustion engine 1 described in this embodiment. May be provided. However, in such an internal combustion engine 1, the air supply passage 71 connected to the intake passage 4 upstream of the intake throttle valve and the intake passage 4 downstream of the intake throttle valve are provided.
And a combustion gas discharge passage 73 connected to the air supply passage 71, the pressure difference between the air supply passage 71 and the combustion gas discharge passage 73 increases with the pressure of the air supply passage 71 particularly when the running state of the vehicle is in a deceleration running state or a sudden acceleration state. Pressure becomes lower.

Therefore, in the combustion type heater 7, an unnecessary air flow is generated from the air inlet 95 toward the combustion gas outlet 63 due to the pressure difference, and is originally determined by the rotation speed of the rotary fan 90. More air than the supplied air flows into the combustion cylinder 40. Therefore, the combustion type heater 7
The air-fuel ratio in the combustion cylinder 40 becomes unstable during the operation of the fuel cell, causing various problems such as lean misfire and difficult ignition.

Therefore, in the internal combustion engine 1 having the combustion type heater 7 of the present invention, the intake passage 4 upstream of the intake throttle valve 14 is
The pressure in the air supply passage 71 and the combustion gas discharge passage so that a stable combustion state is maintained in the combustion type heater 7 even in a situation where a large differential pressure is generated between the intake passage 4 downstream of the intake throttle valve 14 and the intake passage 4. A pressure adjusting mechanism 53 that adjusts the pressure inside 73 is provided. Hereinafter, the pressure adjusting mechanism 53 according to the gist of the present invention will be described.

As shown in FIG. 3, the pressure adjusting mechanism 53 is provided with a valve body 54 provided in the middle of the air supply passage 71 and the valve body 54 in accordance with a differential pressure between the air supply passage 71 and the combustion gas discharge passage 73. And an actuator 55 that opens and closes.

The valve element 54 is a butterfly valve rotatably provided around a required shaft provided in the air supply passage 71 as a center of rotation, and normally blocks the flow of air in the air supply passage 71. It is fixed at a neutral position (indicated by a phantom line in the figure) so as not to exist. Here, the normal state means that the pressure at the connection point C1 and the pressure at the connection point C2 are substantially equal.

The actuator 55 has a diaphragm 56 inside as shown in FIG.
A first pressure chamber 55a communicating with the air supply passage 71 located on the downstream side of the valve body 54, and a second pressure chamber 55b communicating with the combustion gas discharge passage 73. , Between the diaphragm 56 and the valve element 54, the movement of the diaphragm 56 is
A rod 57 is provided so as to transmit the force to the rod.

When the pressure in the combustion gas discharge passage 73 becomes lower than the pressure in the air supply passage 71, a differential pressure is generated between the first pressure chamber 55a and the second pressure chamber 55b, and the diaphragm 56 The second pressure chamber 55b is deformed toward the pressure chamber 55b (direction A in the figure). The rod 57 extended from the diaphragm 56 is also drawn into the actuator main body 55c with the deformation of the diaphragm 56, and the valve body 54 rotates in the direction A 'in the drawing to narrow the flow path in the air supply passage 71. .

Therefore, the flow rate of the air flowing through the air supply passage 71 decreases, and the pressure difference between the air supply passage 71 downstream of the valve body 54 and the combustion gas discharge passage 73 decreases. Therefore, excessive inflow of air into the combustion type heater 7 and unnecessary flow of air in the combustion type heater 7 can be suppressed. As described above, in the internal combustion engine having the combustion heater according to the present invention, by providing the pressure adjusting mechanism 53 between the air supply passage 71 and the combustion gas discharge passage 73, the upstream and downstream of the intake throttle valve 14 is provided. Even when a large differential pressure occurs, a stable combustion state is maintained in the combustion type heater 7.

The pressure adjusting mechanism 53 employed in the internal combustion engine 1 of the present invention is not limited to the above-described example. For example, as shown in FIG. The pressure adjusting mechanism may include a cylinder 61 for opening and closing the valve body 60 and a piston 60a.

The pressure adjusting mechanism 53 includes a cylinder 61 disposed to connect the air supply passage 71 and the combustion gas discharge passage 73 as shown in FIG.
A piston 60a slidably provided therein, and a valve body 60 provided in the piston 60a and extending toward the combustion gas discharge passage 73, and an air supply passage 71
Is higher than the pressure of the combustion gas discharge passage 73, the pressure of the air supply passage 71 causes the piston 60a to move toward the combustion gas discharge passage 73 (in the direction B in the drawing), thereby causing the flow path of the combustion gas discharge passage 73 to move. It is narrowed by the valve body 60.

Accordingly, the pressure in the combustion gas discharge passage 73 is increased by the combustion gas discharged from the combustion type heater 7, and the pressure difference between the air supply passage 71 and the combustion gas discharge passage 73 is reduced. Therefore, unnecessary air flow generated in the combustion type heater 7 can be suppressed. Note that the valve body 60 is normally housed in the cylinder 61 together with the piston 60a.

As described above, in the internal combustion engine 1 having the combustion type heater 7 according to the present invention, excessive inflow of air into the combustion type heater 7 is suppressed, and unnecessary air flow in the combustion type heater 7 is suppressed. can do. Therefore, good ignitability of the combustion heater 7 and a stable combustion state can be maintained.

In the above-described embodiment, the difference between the pressure in the air supply passage 71 and the pressure in the combustion gas discharge passage 73 is detected by a mechanical element such as an actuator, and the pressure control valve 5 is used.
4 is controlled, for example, the pressure control valve 5
4, a stepping motor and the like are further provided, and a pressure sensor is provided in each of the air supply passage 71 and the combustion gas discharge passage 73. The ECU 11 calculates a differential pressure based on a value (pressure) detected by each pressure sensor. The pressure control valve 54 may be opened and closed by controlling the stepper motor based on the calculated value. That is, a pressure adjusting mechanism including an electric element may be used.

In the above-described embodiment, the pressure adjustment valve 54 is provided in one of the air supply passage 71 and the combustion gas discharge passage 73 to adjust the pressure so as to reduce the differential pressure. A pressure control valve 54 is provided in both the air supply passage 71 and the combustion gas discharge passage 73 so that each passage 7
It is good also as a structure which adjusts pressure so that the pressure of 1 and 73 may mutually approach.

The above-described combustion type heater 7 may be operated when the engine is stopped. The reasons for operating the combustion type heater 7 when the engine is stopped are to improve the startability of the engine body 3, to reduce harmful substances discharged from the engine body 3 immediately after the engine is started, Of the heating performance in the above.

However, when the engine is stopped, the flow of air toward the engine body 3, that is, no intake is performed, so that the air filled in the intake passage 4 stays in the intake passage 4. Therefore, the fuel gas discharged from the combustion gas discharge passage 73 to the intake passage 4 may flow into the air supply passage 71. Therefore, the combustion gas mixes with the air supplied to the combustion type heater 7 and makes the combustion state in the combustion type heater 7 unstable.

When the engine is stopped, the combustion type heater 7
When the operating time of the air conditioner becomes longer, the air filled in the intake passage 4 is consumed for combustion in the combustion type heater 7, and the intake passage 4 is filled with the combustion gas instead. Therefore, it becomes difficult to secure the air required for combustion in the combustion type heater 7, and the combustion type heater 7 cannot be operated continuously.

Therefore, in the internal combustion engine 1 of the present invention, a combustion gas discharge path is formed in the internal combustion engine 1 so that the combustion type heater 7 can be continuously operated in a good combustion state even when the engine is stopped. In addition, the combustion gas discharged from the combustion type heater 7 is quickly discharged to the outside of the intake passage 4, and the combustion gas is prevented from entering the air supply passage 71.

That is, when operating the combustion type heater 7 when the engine is stopped, the connection points C1 and C
The intake throttle valve 14 separates the combustion gas from the fuel injection valve 2 to prevent combustion gas from flowing upstream of the intake throttle valve.
At the same time, the EGR valve 8a is opened to connect the intake passage 4 and the exhaust passage 6 downstream of the intake throttle valve, thereby forming a combustion gas discharge path in the internal combustion engine 1.

Therefore, when the rotary fan 90 starts rotating with the operation of the combustion type heater 7, only air flows into the air supply passage 71 connected to the combustion type heater 7. Further, the combustion gas flowing into the intake passage 4 via the combustion gas discharge passage 73 reaches the exhaust passage 6 via the EGR valve 8a and the EGR passage 8b, and is discharged to the atmosphere via the catalytic converter 6a and the muffler.

FIG. 5 is a diagram showing the flow of air (combustion gas) of the internal combustion engine when the engine is stopped. That is, as shown in FIG. 5, when the engine is stopped, the intake passage 4 upstream of the intake throttle valve → the intake supply passage 71 → the rotary fan 90 → the combustion heater 7 → the combustion gas discharge passage 73 → the intake air downstream of the intake throttle valve. Passage 4 → EGR passage 8 b → Exhaust passage 6
→ Air (combustion gas) flows through the internal combustion engine 1 via a path such as the atmosphere.

As described above, according to the present invention, when the engine is stopped, the intake throttle valve 14 is intentionally closed, and the EGR valve 8a is opened to bypass the intake passage 4 and the exhaust passage 6. 7 enables efficient discharge of the combustion gas accompanying the combustion. Therefore, since combustion gas does not stay in the intake passage 4, the combustion type heater 7 can be operated continuously and in a stable combustion state even when the engine is stopped.

Hereinafter, control performed in the ECU 11 until the combustion type heater 7 reaches the operating state will be described. FIG. 6 is a control flowchart schematically showing a program processed in the ECU 11.

In operating the combustion type heater 7,
First, as a process to be executed, the ECU 11 determines whether or not the engine body 3 is in a stopped state (step 101). In determining the stop state of the engine body 3, the stop state of the engine body 3 is confirmed based on, for example, an output signal from a crank angle sensor (not shown) input to the ECU 11. Here, the crank angle sensor is a sensor provided on a drive shaft (crank shaft) of the engine body 3 for detecting the number of revolutions of the drive shaft. Therefore, when the output signal from the crank angle sensor is an output signal corresponding to the rotation speed “0”, it can be considered that the engine body 3 is in the stopped state.

When the stop state of the engine body 3 is confirmed in step 101, the ECU 11 determines whether the intake throttle valve 14 is in a closed state (step 102). In checking the closed state of the intake throttle valve 14 in step 102, for example, the intake throttle valve 1
The closed state of the intake throttle valve 14 is confirmed based on an output signal from an intake throttle valve 14 opening degree sensor (not shown) provided in the intake valve 4.

If the closed state of the intake throttle valve 14 is not confirmed in step 102, the combustion gas discharged from the combustion gas discharge passage 73 may flow into the air supply passage 71 as described above. Valve 14
Is forcibly closed (step 103). Intake throttle valve 1
When closing the intake throttle valve 14, the intake throttle valve 14 is fixed at a position where the intake throttle valve 14 is closed by controlling a stepper motor that opens and closes the intake throttle valve 14 in conjunction with the operation of an accelerator pedal (not shown) provided in the vehicle interior. I do.

After it is confirmed in step 102 that the intake throttle valve 14 is closed, the ECU 11
The valve 8a is opened to bypass the intake passage 4 and the exhaust passage 6 (step 104). Step 104 for opening the EGR valve 8a may be performed in the above-described valve closing processing of the intake throttle valve 14 (step 102).

When the EGR valve 8a is opened in step 104, the EG
A drive current is applied to the R valve 8a to open the valve. When the EGR valve 8a is opened, the cylinder 3a of the engine body 3 is opened.
The intake passage 4 and the exhaust passage 6 downstream of the intake throttle valve are communicated with each other, and a discharge path of the combustion gas discharged from the combustion heater 7 is formed in the internal combustion engine 1. And ECU
At 11, the combustion type heater 7 is operated (step 10).
5).

In step 101, the engine body 3
Is in the operating state, the combustion gas discharged from the combustion gas discharge passage 73 is immediately sucked into the engine main body 3 together with the air required for combustion in the engine main body 3, so that the intake throttle valve 14 The combustion type heater 7 can be operated without controlling the EGR valve 8a.

In the present invention, a preferable example of the engine main body 3 is an internal combustion engine capable of lean burn operation such as a direct-injection lean-burn gasoline engine or a diesel engine. Although not applied in the present embodiment, the present invention is also useful for an internal combustion engine having a supercharger as a component of the internal combustion engine.

When the engine is stopped, the combustion type heater 7
The exhaust gas recirculation device (EGR device) 8
Is used to form a combustion gas discharge path, but a bypass path (exhaust recirculation path) dedicated to the combustion type heater 7 is formed between the intake path 4 and the exhaust path 6 downstream of the intake throttle valve to perform combustion. The gas may be discharged.

In the above-described embodiment, when the engine is stopped, the intake throttle valve 14 and the EGR valve 8a are controlled to form a combustion gas discharge path in the internal combustion engine 1. In the internal combustion engine having the above, the intake throttle valve 14 and the EGR valve 8a may be controlled not only when the engine is stopped but also when the engine speed is low, such as during idling, to form a combustion gas discharge path. In this case, the same effect as that obtained when the engine is stopped can be expected.

In the present embodiment, the intake throttle valve 14
And the EGR valve 8a is opened to form a combustion gas exhaust path. However, in the cylinder 3a of the engine main body, an intake valve and an exhaust valve (not shown) provided in the cylinder 3a overlap (both are not shown). In the open state, the combustion gas can flow down to the exhaust passage 6 through the engine body 3, so that only the intake throttle valve 14 may be closed to operate the combustion heater 7.

[0085]

As described above, according to the present invention, even in an internal combustion engine provided with an intake throttle valve in the intake passage, a good combustion state can be maintained regardless of whether the engine is operating or stopped. An internal combustion engine having a type heater can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an outline of an internal combustion engine having a combustion type heater according to the present invention.

FIG. 2 is a sectional view of the combustion heater according to the embodiment of the present invention.

FIG. 3 is a diagram showing a pressure adjusting mechanism according to the embodiment of the present invention.

FIG. 4 is a diagram showing another example of the pressure adjusting mechanism according to the embodiment of the present invention.

FIG. 5 is a diagram showing flows of air and combustion gas in the internal combustion engine when the engine is stopped.

FIG. 6 is a control flowchart of the combustion heater according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Engine main body 4 Intake passage 5 Combustion supply device 5a Fuel injection nozzle 5b Fuel distribution pipe 6 Exhaust passage 6a Catalytic converter 7 Combustion heater 8 Exhaust gas recirculation device (EGR device) 8a EGR valve 8b EGR passage 10 Heater core 11 ECU 13 Air Cleaner 14 Intake Throttle Valve 37 Heater Internal Cooling Water Flow 37a Cooling Water Inlet 37b Cooling Water Outlet 40 Combustion Cylinder 41 Partition Wall 43 Outer Wall 48 Combustion Chamber 50 Electric Water Pump 53 Pressure Control Mechanism 54 Valve Element 55 Actuator 55a Pressure Chamber 55b First 2 pressure chamber 55c actuator main body 56 diaphragm 57 rod 60 valve body 60a piston 61 cylinder 62 air supply port 63 combustion gas discharge port 71 air supply path 73 combustion gas discharge path 88 fuel introduction path 89 fuel pump 90 rotary pump 92 Motor 93 Housing 95 Air inlet C1 Connection point between air supply passage 71 and intake passage 4 C2 Connection point between combustion gas discharge passage 73 and intake passage 4 F Flame S Internal space of housing W Cooling water circuit W1 Cooling water introduction Passage W2 Cooling water discharge path W3 Cooling water discharge path

Claims (6)

[Claims] An internal combustion engine is provided with an intake throttle valve for restricting intake air flowing through an intake passage. Air for combustion is introduced and mixed with fuel to generate an air-fuel mixture. An internal combustion engine having a combustion-type heater adapted to use heat of exhausted combustion gas, comprising: an air supply passage that takes in the combustion air from an intake passage upstream of the intake throttle valve into the combustion-type heater; A combustion gas discharge passage for allowing combustion gas discharged along with combustion of the air-fuel mixture to flow from the combustion heater to an intake passage downstream of the intake throttle valve; a pressure in the air supply passage and a pressure in the combustion gas discharge passage An internal combustion engine having a combustion type heater, comprising: pressure adjusting means for adjusting pressure. 2. The pressure adjusting means is interposed between the air supply passage and the combustion gas discharge passage, and controls the pressure in the air supply passage and the pressure in the combustion gas discharge passage so as to be close to each other. An internal combustion engine having a combustion heater according to claim 1, wherein the adjustment is performed. 3. A pressure control valve is provided in at least one of the air supply passage and the combustion gas discharge passage, and the pressure control means controls a pressure in the air supply passage and a pressure in the combustion gas discharge passage. The internal combustion engine having a combustion-type heater according to claim 1 or 2, wherein the pressure control valve is controlled according to the differential pressure of the combustion heater. 4. An exhaust recirculation passage for communicating an exhaust passage for discharging exhaust discharged from the internal combustion engine to the outside of the engine and an intake passage downstream of the intake throttle valve by bypassing a cylinder of the internal combustion engine. An internal combustion engine having the combustion heater according to any one of claims 1 to 3. 5. An internal combustion engine having a combustion heater according to claim 1, further comprising an intake throttle valve control means for closing said intake throttle valve when said combustion heater operates. organ. 6. An internal combustion engine having a combustion type heater according to claim 5, wherein said intake throttle valve control means closes said intake throttle valve at least when the internal combustion engine is stopped.