JP2001027119A - Internal combustion engine having combustion heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent inflow of excess air into a combustion heater even when operating a supercharger, and to prevent lowering of engine power even when suction gas is deflated from a suction passage as combustion air for the combus tion heater, in an internal combustion engine comprising the supercharger and the combustion heater. SOLUTION: This engine 1 comprises a combustion heater 91 adapted to raise temperature of engine related elements by using heat of combustion gas, a supercharger 15 adapted to raise pressure of suction gas, an air supply pipe 71 adapted to supply the suction gas which was raised in pressure to the combustion heater 91, and a combustion gas exhaust pipe 73 adapted to exhaust the combustion gas into an exhaust pipe 42. In this case, the engine 1 comprises an ECU 11 as a pressure differential obtaining means adapted to obtain a pressure differential between manifold pressure and exhaust pressure, and a cross valve 86 as a combustion gas flow control means adapted to control flow of combustion gas to be injected into the combustion gas exhaust pipe 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 improving the cold startability of an internal combustion engine by increasing the temperature of engine cooling water and other engine-related elements of the internal combustion engine, and warming up the engine. The present invention relates to an internal combustion engine having a combustion-type heater for promoting the performance and improving the performance of a vehicle interior heating device.

[0002]

2. Description of the Related Art It is desired that an internal combustion engine be improved in startability, particularly in cold weather, to promote warm-up. Above all, diesel engines and other lean-burn engines generate less heat than normal gasoline engines.

[0003] Therefore, a combustion type heater is attached to the internal combustion engine, and the combustion type heater heats the engine cooling water and other heat medium, and the heated heat medium is used as a water jacket of the engine main body, a heater core for cabin heating, and the like. A technique for raising the temperature of these necessary portions by sending them to the necessary portions is known (for example, see Japanese Patent Application Laid-Open No. 60-78819).

[0004] As the combustion type heater, a vaporization type combustion heater which vaporizes the fuel for combustion into a vaporized fuel, ignites the vaporized fuel to produce a fire, and grows the fire to generate a flame is preferable.

As is well known, a vaporization type combustion heater includes a combustion chamber for generating a flame, a fuel supply unit for supplying liquefied fuel for combustion to the combustion chamber, and a fuel for vaporizing the liquefied fuel supplied by the fuel supply unit. The vaporization section, a glow plug as an ignition section that ignites the vaporized fuel vaporized by the fuel vaporization section to generate a fire, and a fire generated by the glow plug are controlled by controlling the amount of air supplied to the fire (air volume). A blower fan that adjusts and produces a flame having an appropriate size and momentum; a cooling water passage through which engine cooling water is absorbed to absorb combustion heat generated during operation of the heater in the engine cooling water; And at least an air flow passage including a combustion gas outlet for discharging combustion gas from the combustion chamber.

[0006]

In the internal combustion engine having the combustion type heater disclosed in the above publication, a part of the intake air flowing through the intake passage is used as combustion air for the combustion type heater (hereinafter referred to as "heater combustion air"). ), The combustion gas is supplied to the combustion chamber and the combustion gas is discharged to the exhaust passage. Therefore, the air inlet and the intake passage are connected by an intake duct, and the combustion gas outlet and the exhaust passage are connected by an exhaust duct.

In the technology described in the above publication, the pressure in the exhaust passage may be higher than the pressure in the intake passage depending on the operating state during operation of the engine. Then, not only can the combustion gas not flow into the exhaust passage, but also there is a possibility that the backflow phenomenon in which the exhaust gas in the exhaust passage flows through the exhaust duct to the combustion heater.

However, even in such a case, the backflow can be prevented by providing a supercharger in the internal combustion engine and increasing the supercharging pressure to boost the intake air. However, if the supercharging pressure is high, the differential pressure between the intake pressure and the exhaust pressure, in other words, the differential pressure generated between the air intake and the combustion gas exhaust of the combustion heater increases, and the combustion chamber The amount of air flowing through becomes excessive. Then, a suitable air volume adjustment cannot be performed only by the air volume adjustment by the blowing fan of the combustion type heater. Therefore, in this case, since excess air continues to flow in the combustion chamber, there is a risk that ignition failure may occur in the combustion type heater, combustion may be unstable due to a lean air-fuel ratio, or misfire may be caused. There is.

In addition, as described above, in an internal combustion engine having a combustion type heater for introducing combustion air from the engine intake passage and discharging combustion gas to, for example, an exhaust passage, the intake air is extracted from the intake passage. The engine intake amount decreases by the amount.
Therefore, if the intake air escapes from the intake passage when the output of the internal combustion engine needs to be increased, such as during supercharging, the supercharging pressure decreases, and therefore, the engine output cannot be increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a problem to be solved is to provide a combustion type heater having a supercharger and increasing the temperature of engine-related elements and other places requiring a temperature rise. When flowing the combustion gas of the combustion heater in the exhaust passage in the internal combustion engine, for example, it is possible to prevent excess air causing misfire or the like in the combustion heater,
It is an object of the present invention to provide an internal combustion engine having a combustion type heater which can prevent an excessive decrease in supercharging pressure such that an engine output is reduced even if intake air is taken out of an intake passage as combustion air for the combustion type heater.

[0011]

SUMMARY OF THE INVENTION An internal combustion engine having a combustion type heater according to the present invention has been invented in view of the above situation, and employs the following means. (1) An internal combustion engine having a combustion-type heater according to the present invention burns an air-fuel mixture obtained by mixing fuel with air introduced through an intake passage of the internal combustion engine to generate combustion gas, and utilizes heat of the combustion gas to generate an engine-related gas. A combustion-type heater that raises the temperature of a component, a supercharger that pressurizes the air in the intake passage, and an air supply path that supplies the air that is pressurized by the supercharger to the combustion-type heater,
In an internal combustion engine having a combustion gas discharge passage for bypassing a cylinder of the internal combustion engine and discharging the combustion gas to an exhaust passage, a pressure difference detecting device for detecting a pressure difference between a pressure in the intake passage and a pressure in the exhaust passage. And a combustion gas flow control means for controlling a flow rate of the combustion gas introduced into the combustion gas discharge path based on the pressure difference obtained by the pressure difference obtaining means.

Here, the term "engine-related element" refers to, for example, engine cooling water or an internal combustion engine body that introduces combustion gas of a combustion heater into intake air. As the "combustion heater", a vaporization combustion heater is preferable.

The "pressure difference obtaining means" is an engine control device for controlling the operation of the entire internal combustion engine, so-called EC
U. The "combustion gas flow control means" includes, for example, a valve device. (2) It is preferable that the combustion gas flow rate control means controls the flow rate of the combustion gas to be constant irrespective of the fluctuation of the pressure difference. (3) The pressure difference obtaining means may calculate and obtain the pressure difference from an engine speed and a load related to the internal combustion engine. (4) The pressure difference obtaining means obtains the pressure difference using a map which is an index for predicting the pressure difference and which indicates the pressure difference based on the engine speed and the load. Can also. (5) The combustion gas flow rate control means may be a two-way valve or a three-way valve, and these valve openings may be determined based on the pressure difference. (6) It is preferable that the combustion gas discharge path and the intake path communicate with each other through a communication path, and the three-way valve is provided at a position where the communication path is connected to the combustion gas discharge path. (7) Where the intake passage and the communication passage are connected
It is desirable that the intake passage is located downstream and near a location connected to the air supply passage.

Here, "near" means "intake passage → air supply passage → combustion heater → part of combustion gas discharge passage → communication passage →
In the path of the intake passage, the proximity is such that excess air does not flow into the combustion type heater during supercharging.

According to the present invention having the above-described structure, for example, the following operation and effect can be obtained. First, in the path of intake passage → air supply passage → combustion heater → combustion gas discharge passage → exhaust passage, at the time of supercharging, air discharged from the intake passage to the air supply passage was subjected to combustion by the combustion heater. After that, it becomes a combustion gas (more precisely, a gas containing the combustion gas and the air), passes through a combustion gas discharge passage, and reaches an exhaust passage.

At this time, if the amount of air drawn out of the intake passage is more than necessary, for example, if air is drawn out of the intake passage more than the amount required for the combustion of the heater, the engine intake amount becomes insufficient and the engine output decreases. Will be invited. However, if the amount of the decrease does not lead to a decrease in the output and does not affect the combustion of the heater, the output does not decrease and there is no problem in the combustion of the combustion type heater.

In the present invention, the pressure difference ΔP between the pressure in the intake passage and the pressure in the exhaust passage is determined by the pressure difference obtaining means at the time of supercharging, and the pressure difference ΔP is introduced into the combustion gas discharge passage based on the obtained pressure difference ΔP. The flow rate of the combustion gas is controlled by combustion gas flow control means.

If the combustion gas flow control means is, for example, a valve device, the flow rate Ga of the combustion gas flowing through the valve device is determined by the pressure difference Δ
It is indicated by the product of P and the opening area S of the valve device. For this reason, the area S is made variable in accordance with the change in the pressure difference ΔP so that the flow rate Ga of the combustion gas introduced into the combustion gas discharge path becomes constant regardless of the change in the pressure difference ΔP. By doing so, the amount of air extracted from the intake passage is also constant. At this time, if the fixed amount of extracted air does not cause a decrease in engine output, the intake air is supplied from the intake passage to the combustion heater as combustion air regardless of the pressure fluctuation at the time of supercharging. In addition, there is no problem of output reduction.

Further, since the combustion gas flow control means can be applied as a two-way valve or a three-way valve, it can be properly used according to the mode to which the present invention is applied. Furthermore, it is considered that a three-way valve is preferably installed at a position where the communication path is connected to the combustion gas discharge path. In that case, the three-way valve communicates the combustion heater, the exhaust passage, and the intake passage via the communication passage and the combustion gas discharge passage. That is, of the three ports of the three-way valve, one port communicates with the communication path, and the remaining two ports respectively communicate with the exhaust gas path side and the combustion type heater side of the combustion gas discharge path.

Therefore, the opening degree of the three-way valve is controlled so that the combustion gas discharge path side becomes smaller during supercharging, in other words, in the engine operating state where the engine speed is high and the load is large, and the combustion gas discharge is controlled. If the flow rate of the combustion gas introduced into the passage is kept constant irrespective of the fluctuation of the pressure difference, it is possible to prevent the engine output from decreasing as described above.

Further, the combustion heater is connected to the intake passage through a series of passages in which a part of the combustion gas discharge passage communicates with the communication passage through the three-way valve and the air supply passage. Even during supercharging, it is possible to prevent excessive combustion gas flow in the combustion type heater. For this reason, the combustion type heater does not cause ignition failure, the air-fuel ratio becomes lean and the flame becomes unstable, so that the combustion is not stabilized or the lean misfire does not occur.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings. <First Embodiment> A first embodiment will be described with reference to FIGS.

The engine 1 exemplified as an internal combustion engine is a diesel engine or a gasoline direct-injection lean burn engine, and FIG. 1 schematically shows the entire structure thereof. The engine 1 includes an engine body 3 having a water jacket containing engine cooling water, an intake device 5 for feeding air required for combustion into a plurality of cylinders of the engine body 3, and an intake device 5.
An exhaust device 7 that, after a mixture of air sent to the cylinder via the air and fuel injected and supplied into the cylinder, burns in a combustion chamber of the engine 1 and discharges exhaust gas from the cylinder into the atmosphere, The EGR device 8 as an exhaust gas recirculation device that suppresses the generation of nitrogen oxides in the cylinder by recirculating exhaust gas from the device 7 to the intake device 5, and burns fuel separately from the engine 1. A combustion type heater 91 that raises the temperature of the engine-related elements by the heat of the combustion gas generated at that time (hereinafter referred to as “combustion heat”); and a vehicle interior heating device that uses the combustion heat to increase the indoor temperature of the engine-equipped vehicle. And an ECU 11 that is an engine control device that controls the operation of the entire engine 1.

The intake device 5 has an intake pipe 14 as an intake passage which starts with an air cleaner 13 for filtering outside air and terminates with an intake port (not shown) of the engine body 3.

A compressor 15 of a turbocharger 15, which is a supercharger for boosting the intake air of the intake pipe 14, is provided between the air cleaner 13 and the intake port.
a, an intercooler 19 for cooling the intake air heated by the heat of compression generated when the compressor 15a is operated, and an intake manifold 22 which is an intake branch pipe and has an intake pressure sensor 49 are sequentially arranged.

The intake pressure sensor 49 provided in the intake manifold 22 is connected to the intake manifold 2.
2 detects an intake pressure in the engine 2 and outputs an electric signal corresponding to the detected value to the ECU 11. The supercharging pressure of the turbocharger 15 is substituted by the intake pressure detected by the intake pressure sensor 49.

An intake throttle valve 51 for controlling the amount of intake air flowing through the intake pipe 14 is provided between the intercooler 19 and the intake manifold 22. Intake pipe 1
4, the combustion type heater 91 is mounted between the intercooler 19 and the intake throttle valve 51.

The exhaust device 7 has an exhaust pipe 42 as an exhaust passage starting from an exhaust port (not shown) of the engine body 3 and terminating at a muffler (not shown). Exhaust pipe 42
An exhaust manifold 28 serving as an exhaust manifold, a turbine 15b of the turbocharger 15, and a catalytic converter 39 serving as an exhaust gas purifying device are sequentially arranged between the exhaust port and the muffler.

The EGR device 8 connects the intake pipe 14 and the exhaust pipe 42 and bypasses the engine body 3 to return exhaust gas from the exhaust port toward the intake side.
It has a pipe 81 and an EGR valve 30 for controlling the amount of exhaust gas flowing through the EGR pipe 81.

The combustion type heater 91 introduces a hot combustion gas into the intake pipe 14. With this introduction, the temperature of the intake air flowing through the intake device 5 is increased. Then, the heated intake air flows through the intake pipe 14 toward the cylinder while containing the combustion gas.

Further, the combustion type heater 91 warms the engine cooling water by the heat of the combustion gas, and the warmed engine cooling water is sent to the heater core 10, the engine body 3, and the like, where the temperature needs to be raised. The temperature of the portion requiring the temperature is increased (only the heater core 10 and the engine body 3 are shown as the portions requiring the temperature increase in the drawing).

The engine 1 is so arranged that the engine cooling water warmed by the combustion type heater 91 can be sent to the above-mentioned required temperature rising point.
Has a heat medium circulation path W that circulates the warmed engine cooling water by an engine water pump (not shown).

The heat medium circulation path W connects the engine body 3 with the combustion type heater 91, and a water pipe W which leads the engine cooling water from the water jacket of the engine body 3 to the combustion type heater 91.
1, a water pipe W2 for guiding the engine cooling water heated by the combustion heater 91 to the heater core 10, and a water pipe W3 for returning the engine cooling water coming out of the heater core 10 to the water jacket of the engine body 3.

The water pipe W1 has an electric water pump 50. The operation of the electric water pump 50 promotes the circulation of the engine cooling water in the heat medium circulation path W by the operation thereof. By operating the electric water pump 50 when the engine is stopped, the heater core 10 can be operated even when the engine is stopped.

Here, a specific structure of the combustion type heater 91 will be described with reference to FIGS. The combustion type heater 91 has a cooling water passage 37 therein (hereinafter, referred to as a “heater internal cooling water passage 37”). The heater internal cooling water passage 37 has a cooling water inlet 37a connected to the water pipe W1 and a cooling water outlet 37b connected to the water pipe W2. Further, the cooling water inlet 37a and the water pipe W1 are
Further, the cooling water discharge port 37b communicates with the water pipe W2, whereby the heater internal cooling water passage 37 forms a part of the heat medium circulation path W. Further, the cooling water passage 37 inside the heater is
The combustion heater 91 is formed so as to circulate around the combustion chamber 48.

The combustion chamber 48 includes a combustion tube 40 as a combustion source that generates the flame F, and a partition 40a that covers the combustion tube 40 to prevent the flame F from leaking to the outside. The combustion chamber 48 is covered with the partition 40a by covering the combustion cylinder 40 with the partition 40a.
a. The partition wall 40 a is also covered with the outer wall 43 of the combustion type heater 91. An annular gap is provided between the partition wall 40a and the outer wall 43, and this gap functions as the heater internal cooling water passage 37. While the engine cooling water flows through the heater internal cooling water passage 37, the engine cooling water receives heat from the combustion chamber 48. That is, the engine cooling water is supplied to the combustion chamber 4
The heat is exchanged with the high-temperature combustion gas in 8 to increase the temperature.

The combustion chamber 48 has a flow port through which gas flowing into and out of the combustion chamber 48 enters and exits. Specifically, the combustion chamber 48 has an air inlet 62 into which combustion air is introduced, and combustion gas outlets 63 and 65 for discharging combustion gas from the combustion chamber 48.

The air intake 62 is located on the side opposite to the side where the flame F exits from the combustion tube 40 in the combustion chamber 48, that is, on the base end side of the combustion tube 40. Also, the combustion gas outlet 63
Is located in the vicinity of the base end of the combustion tube 40 in the combustion chamber 48, and the combustion gas discharge port 65 is located on the side where the flame F exits from the combustion tube 40 and faces the partition wall 40 a in a state facing the flame F.
And the outer wall 43 is provided in a penetrating state.

Therefore, the combustion gas flowing through the combustion gas discharge port 63 is cooled by heat exchange with the engine cooling water, but the combustion gas flowing through the combustion gas discharge port 65 is cooled between the combustion gas and the engine cooling water. Heat exchange is hardly performed. For this reason, the temperature of the combustion gas discharged from the combustion gas discharge ports 63 and 65 is lower at the temperature of the combustion gas discharged from the combustion gas discharge port 63, and the temperature of the combustion gas discharged from the combustion gas discharge port 65 is lower. high.

The reason why the two combustion gas discharge ports for discharging the combustion gas having different temperatures are provided is when it is necessary to quickly warm the temperature of the supply destination according to the supply destination of the combustion gas. This is because the combustion gas having a higher heat and the combustion gas having a lower heat as compared with the combustion gas may be used as needed. However, the proper use thereof is not the subject of the present invention, and the description is omitted.

The combustion gas discharge ports 63 and 65 are connected by a parallel connection pipe 74 extending in parallel with the longitudinal direction of the combustion type heater 91. The air inlet 62 transfers a part of the intake air supercharged by the turbocharger 15 to the intake pipe 14.
From the combustion heater 91 as combustion air.
Through an air supply pipe 71 serving as an air supply path for supplying air to the intake pipe 14. The point at which the air supply pipe 71 is connected to the intake pipe 14 is indicated by reference numeral C1.

The combustion gas outlet 65 is connected to the exhaust pipe 42.
At the upstream side of the catalytic converter 39 in FIG. The combustion gas discharge pipe 73 is a bypass pipe that bypasses the engine body 3 including the cylinder, and merges with the parallel connection pipe 74.

The combustion gas discharge port 63 communicates with the exhaust pipe 42 via the parallel connection pipe 74 and the combustion gas discharge pipe 73. The combustion gas discharge pipe 73 has valve devices 78 and 86 in the middle thereof. The valve device 78 is located on the upstream side of the combustion gas discharge pipe 73, and the valve device 86 is located on the downstream side.

The valve device 78 connects the combustion gas discharge pipe 73 to the combustion heater 91 via the valve device 78. Also, the valve device 7
The opening and closing of the combustion gas outlet 65 is controlled by the operation of FIG.
Inside the valve device 78, there is a valve chamber 79 having a valve body 80 for opening and closing the combustion gas discharge port 65. The valve chamber 79 has two openings 79a, 79b, these openings 79a and 7b.
9b communicates with the combustion gas discharge port 65 and the combustion gas discharge pipe 73, respectively. The valve device 78 is provided with a valve body 80.
Is provided. When the valve body 80 is actuated by the actuator 82, the opening 79a is fully opened or fully closed as required. By opening and closing, the opening 7
Combustion gas may or may not flow through the combustion gas outlet 65 leading to 9a.

The valve device 78 may be either fully open or fully closed with ON / OFF control or open and close linearly. In this embodiment, the former is used. The combustion gas flow rate Ga flowing through the valve device 78 is determined by the pressure difference Δ between the pressure in the intake passage and the pressure in the exhaust passage.
P and the opening area (opening amount) S of the opening 79a of the valve device 78
The product of

Further, the combustion gas flows into and out of the valve device 78 in a total of two directions, one direction in which the combustion gas enters and one direction in which the combustion gas exits. For this reason, the valve device 7
8 can be called a two-way valve.

Further, a fuel supply pipe 88 for introducing fuel from the outside to the combustion cylinder 40 is connected to the combustion cylinder 40. The fuel supply pipe 88 is connected to a fuel pump 89,
Upon receiving the pump pressure of the fuel pump 89, the fuel is discharged from the fuel supply pipe 88 to the combustion cylinder 40.

The combustion cylinder 40 has a glow plug (not shown) for igniting the fuel supplied by the fuel supply pipe 88. The outer wall 43 of the combustion type heater 9 has a housing 93 containing a blower fan 90 as a blower on the side of the combustion tube 40 opposite to the side where the flame F is emitted.

The blower fan 90 has a motor 92 as a drive source.
The combustion air introduced from 1 is sent into the combustion chamber 48.
The housing 93 has an air intake 95 for taking in air from outside, and the air supply pipe 71 is connected to the air intake 95. The housing 93 has an internal space Sp communicating with the air intake 62. Therefore, the air inlet 62 is indirectly connected to the air supply pipe 71 via the internal space Sp.

Then, by operating the motor 92 and rotating the blower fan 90, the flow rate of the air introduced into the housing 93 from the intake pipe 14 via the air supply pipe 71 is adjusted. The air introduced into the housing 93 is supplied from the air intake 62 to the combustion cylinder 40 as combustion air via the internal space Sp.

The combustion gas emitted after the fuel is burned by the combustion air thereafter reaches the combustion gas discharge passage 73 from the combustion heater 91, and thereafter, if necessary, by the valve device 86, the intake pipe 14 or the exhaust pipe 42. Will be introduced. Further, an appropriate portion of the combustion gas discharge pipe 73 downstream of the valve device 78 communicates with a communication passage 73 a connecting the combustion gas discharge pipe 73 and the intake pipe 14. The valve device 86 is provided at a position where the communication passage 73a connects to the combustion gas discharge pipe 73. The valve device 86 of the combustion gas discharge pipe 73
The part on the upstream side is indicated by reference numeral 73b, and a series of passages consisting of this part 73b and the communication passage 73a is indicated by reference numeral 8b.
Indicated by 7.

The location C2 where the communication passage 73a is connected to the intake pipe 14 is the location C where the intake pipe 14 is connected to the air supply pipe 71.
It is downstream and close to 1. Here, “neighborhood” means
In the path of the intake pipe 14 → the air supply pipe 71 → the combustion type heater 91 → the part 73 b of the combustion gas discharge pipe 73 → the communication passage 73 a → the intake pipe 14, no excess air flows into the combustion type heater 91 at the time of supercharging. A state where the connection points C1 and C2 are close to each other.

The valve device 86 has three inside ports, a first port as an inlet port which is always open, and a second port and a third port as outlet ports which are opened and closed by the operation of the valve device 86. Has a port.

The first port is connected to the combustion gas discharge pipe 73 in a state where the first port is directed to the upstream side of the combustion gas discharge pipe 73. Further, the second port is connected to the communication passage 73 a so as to be continuous with the intake pipe 14. And the third port is
The combustion gas discharge pipe 73 is connected to the combustion gas discharge pipe 73 in a state of being directed downstream of the combustion gas discharge pipe 73 so as to be connected to the exhaust pipe 42. Since the valve device 86 has such three ports, it is hereinafter referred to as a three-way valve 86.

As shown in FIG. 4, the three-way valve 86 includes a case body 86a, a valve body 86b that moves in the case body 86a in the longitudinal direction, and an operating portion 86 that operates the valve body 86b.
c.

At the center of the case 86a, the case 86a
And has a dividing plate 86e having an opening 86d at the center. The valve body 86b is moved by the operating portion 86c in the longitudinal direction of the case body 86a.
1 and a pair of valve portions 86b2 and 86b3 attached to the distal end portion and the central portion of the stem 86b1, respectively.
It corresponds to the port and the opening 86d and opens and closes them.

When the operating portion 86c operates the valve element 86b, in other words, the valve element 86b is
The second and third ports open and close depending on where they are located in 6a. For example, the valve element 86b
Is moved to the position indicated by the two-dot chain line in FIG.
4 is fully opened and the third port is fully closed. As a result, a path indicated by a two-dot chain line in FIG. 4 connecting the first port and the second port is formed. Also, the valve element 86b is
Is moved to the position indicated by the solid line, the opening 86d is fully closed and the third port is fully opened. As a result, the path indicated by the solid line arrow in FIG. 4 connecting the first port and the third port is formed.
The second port and the third port are opened and closed linearly by the valve element 86b.

The three-way valve 86 controls the flow rate of the combustion gas at the third port according to the position of the valve body 86b between the opening 86d of the dividing plate 86e and the third port. It is a gas flow control means.

The flow rate Ga of the combustion gas flowing through the third port
Is the pressure difference ΔP between the pressure in the intake pipe 14 and the pressure in the exhaust pipe 42 and the opening area (opening amount) S of the third port.
The product of

Then, at the time of supercharging, the combustion gas having passed through the third port flows through the combustion gas discharge pipe 73 to a connection point C3 in the exhaust pipe 42 near the upstream side of the catalytic converter 39. At this time, if the opening degree of the third port is large, the flow rate of the combustion gas flowing through the third port to the exhaust pipe 42 is, to be precise, the intake pipe 14 → the air supply pipe 71 → the combustion heater 91 → the combustion gas discharge. In the path from the pipe 73 to the exhaust pipe 42, at the time of supercharging, the flow rate of the combustion gas mixed air composed of the intake air drawn from the intake pipe 14 to the air supply pipe 71 and the combustion gas of the combustion type heater increases. Will decrease. Therefore, the engine output decreases.

Therefore, when the pressure difference ΔP is not at the target pressure difference described below, the three-way valve 86 moves the valve body 86 b closer to the third port so as to reduce the opening amount of the third port communicating with the exhaust pipe 42. And lower the opening of the third port. Therefore, in that case, the flow rate of the combustion gas through the third port is reduced.

The "target pressure difference" is defined as the pressure difference between the pressure in the intake pipe 14 and the pressure in the exhaust pipe 42 at the time of supercharging. In other words, the amount of intake air drawn from the intake pipe 14 to the air supply pipe 71 is small, and therefore, the pressure difference that can prevent the engine output from excessively lowering because the amount of decrease in engine intake is small. I do.

The ECU 11 comprises a central processing controller CPU, a read-only memory ROM, a random access memory RAM, an input interface circuit, an output interface circuit, and the like, which are interconnected by a bidirectional bus.

Various sensors are connected to the input interface circuit via electric wiring. The output interface circuit includes an EGR valve 30, an electric water pump 50, a glow plug of a combustion cylinder 40, a valve device 78, and a three-way valve. The valve 86, the fuel pump 89, the motor 92 and the like are connected via electric wiring.

The sensors connected to the input interface circuit include the intake pressure sensor 49, an air flow meter attached to the intake pipe 14, and a catalytic converter 39.
A catalyst temperature sensor attached to the water jacket, a water temperature sensor for detecting the temperature of the cooling water contained in the water jacket, an accelerator position sensor attached to the accelerator pedal or an accelerator lever operating in conjunction with the accelerator pedal, an ignition switch, a starter switch, A rotation speed sensor and the like can be exemplified. These sensors output an electrical signal corresponding to the detected value and send it to the ECU 11.

The ECU 11 comprehensively determines the operating state of the engine 1 based on the output signal values of the various sensors described above. Then, fuel injection control and the like are performed based on the determination result, and operation control of the combustion heater 91 is performed.

The method for obtaining the pressure difference between the pressure in the intake pipe 14 and the pressure in the exhaust pipe 42 is as follows.
That is, if the engine speed Ne and the magnitude of the load Te (for example, the fuel injection amount and the accelerator opening) Te related to the engine 1 are known, a map is used as an index indicating the pressure difference based on the magnitude. The pressure difference is CP
U predicts. Therefore, the CPU is referred to as pressure difference prediction means.

Since the CPU is included in the ECU 11, the ECU 11 may be referred to as pressure difference predicting means. A method for predicting a pressure difference using the map will be described with reference to FIGS.

FIG. 5 is a map M1 as an engine load-engine speed diagram showing the engine load Te on the vertical axis and the engine speed Ne on the horizontal axis. Map M
In FIG. 1, the region indicated by the symbol Ar indicates that the pressure in the intake pipe 14 and the pressure in the exhaust pipe 42 are different if the engine load Te and the engine speed Ne are within this range, that is, if the intersection of the two is within the region Ar. Is at least equal to the target pressure difference.

The four graph lines shown in the map M1 show the pressure differences Pd1, Pd2, Pd3 and Pd when the engine load Te and the engine speed Ne are at certain values.
It is a pressure difference prediction line which predicts and shows d4. Although only four types of pressure difference prediction lines are shown here for the sake of simplicity, the map M1 has more subdivisions in practice, and the map M1 has many pressure difference prediction lines.

When the pressure difference is predicted using the map M1, for example, the following is performed. In the case where the engine speed is Ne2 and the engine load Te is Te2, if these intersections are taken, the intersection is within the region Ar. Therefore, when the engine speed Ne is Ne2 and the engine load Te is Te2, the pressure difference is at the target pressure difference, and the pressure difference can be predicted to be Pd2. Therefore, when the engine speed Ne is Ne2,
If the engine load Te is in the state of Te2, it is considered that there is no problem in maintaining the pressure difference at the target pressure difference.

When the engine speed Ne is Ne1 and the engine load Te is Te1, the intersection of the two is in the region Ar
Outside. Therefore, when the engine speed Ne is Ne1 and the engine load Te is Te1, the pressure difference is not at the target pressure difference, and it can be predicted that the pressure difference is Pd1.

If the pressure difference Pd1 remains unchanged, excess air flows into the combustion chamber 48, so that not only does the engine output decrease, but also the combustion type heater 91 becomes unable to ignite or causes misfire. There is a risk of doing so.

Therefore, the three-way valve 86 is operated to operate the valve 86
b, the degree of opening of the third port side is reduced.
Excess air does not flow into 8. Thus, the map M1
Is for predicting the pressure difference from the engine load-engine speed, the map M1 is referred to as a pressure difference prediction map.

When the pressure difference is not at the target pressure difference as described above, the three-way valve 86 is used to prevent the engine output from lowering and to prevent the combustion type heater 91 from becoming ignitable or causing misfire. The map M2 in FIG. 6 is used to determine the opening degree of the pressure sensor based on the pressure difference.

Similar to the map M1, the map M2 is an engine load-engine speed diagram having the engine load Te on the vertical axis and the engine speed Ne on the horizontal axis. The four types of graph lines shown in the map M2 indicate the degrees of opening of the third port side by the valve element 86b, which are opening 1, opening 2, opening 3 and opening 4, respectively. These opening degrees indicate that the larger the numerical value, the larger the opening degree of the third port.
Although only four graph lines indicating the degree of opening are shown here for the sake of simplicity, the graph M2 is actually further subdivided, and thus the map M2 has many graph lines indicating the degree of opening. Have.

Using the map M2, the third valve body 86b
To determine the port opening, for example, the following is performed. In the case where the engine speed that is not at the target pressure difference is Ne1 and the engine load Te is Te1, the intersection in that case is on the graph line of the opening degree 1. Therefore, the valve element 8
If the third port is adjusted to the opening degree 1 by 6b, it means that even if the pressure difference is not the target pressure difference, excess air can be prevented from flowing into the combustion type heater 91.

The map M2 indicates the engine load Te.
The valve element 86b is operated so that the opening of the third port becomes smaller as the engine speed Ne increases, and conversely, the opening of the third port increases as the engine load Te and the engine speed Ne decrease. This indicates that the valve element 86b is operated linearly.

The amount of the combustion gas mixed air flowing through the exhaust pipe 42 is determined according to the opening degree obtained from the map M2. Valve 86
If the opening of the third port due to b is small, the amount of the combustion gas mixed air flowing through the combustion gas exhaust pipe 73 toward the exhaust pipe 42 is small, and if the opening of the third port is large, the flow rate of the combustion gas mixed air is small. Are many.

The maps M1 and M2 correspond to the R
It is stored in the OM and is called by the CPU as needed. Next, referring to the flowchart of FIG.
A program for realizing an opening degree control execution routine of the three-way valve 86 controlled by 1 will be described. It is assumed that the valve device 78 is in a fully open state.

First, in S101, the ECU 11
It is determined whether a condition for discharging the exhaust gas from the combustion type heater 91 to the exhaust pipe 42 is satisfied. The conditions are, for example, when the catalyst contained in the catalytic converter 39 needs to be promoted to warm up, when the catalyst needs poisoning recovery processing such as SOx poisoning or SOF poisoning, and when the catalyst converter 39 needs reduction processing or the like. This means that the engine 1 is present.

If it is determined in S101 that the above condition is satisfied, the process proceeds to S102, and if it is negative, the routine is terminated. In S102, the engine speed Ne detected by the engine speed sensor and the engine load Te calculated from the accelerator opening detected by the accelerator position sensor are read.

At S103, a map M is calculated based on the engine speed Ne and the engine load Te obtained at S102.
Predict the pressure difference from 1. In S104, if the pressure difference obtained in S103 is not equal to the target pressure difference, the third port of the three-way valve 86, which is a flow regulating valve, is opened from the engine speed Ne and the engine load Te using the map M2. Ask for degrees.

In S105, the opening degree obtained in S104 is changed to the third value.
The position of the valve element 86b of the three-way valve 86 is controlled so that a port is formed. As a result, no excess air flows into the combustion chamber. <Modification> Also, instead of predicting the pressure difference, the intake pressure actually detected by the intake pressure sensor 49 is sent to the ECU as an electric signal, and the CPU calculates the pressure difference ΔP based on the electric signal by an appropriate arithmetic expression. And the exhaust pipe 4
2, an exhaust pressure sensor (not shown) can be provided, and the actual intake / exhaust pressure difference ΔP can be obtained from the detected values of the intake pressure sensor and the exhaust pressure sensor.

Further, even if the map for obtaining the pressure difference ΔP is not used, if the engine speed Ne and the magnitude of the load Te relating to the engine 1 are known, C
The PU can also calculate and know the pressure difference.

In any case, since the final calculation of the pressure difference requires the arithmetic processing of the CPU,
(ECU 11) can be referred to as pressure difference obtaining means. <Operation and Effect of First Embodiment> Next, the operation and effect of the first embodiment will be described.

In the engine 1 according to the first embodiment,
At the time of supercharging, the pressure in the intake pipe 14 becomes larger than the pressure in the exhaust passage 42. Therefore, from the intake pipe 14 to the air supply pipe 7
The air that has entered the combustion heater 91 via 1 flows in the order of the intake pipe 14 → the air supply pipe 71 → the combustion heater 91 → the combustion gas discharge pipe 73 → the exhaust pipe 42.

In other words, from the intake pipe 14 to the air supply pipe 7
The air extracted to 1 is supplied to the combustion type heater 91 for combustion, becomes a combustion gas mixed air, passes through the combustion gas discharge pipe 73, and reaches the exhaust pipe 42.

Therefore, the engine intake air amount is reduced by the amount that the air is evacuated from the intake pipe 14 as it is.
This leads to a reduction in engine output. But engine 1
Then, the pressure difference between the pressure in the intake pipe 14 and the pressure in the exhaust pipe 42 is determined by the ECU 11 as pressure difference obtaining means, and based on the determined pressure difference, the flow rate of the combustion gas introduced into the combustion gas exhaust pipe 73 is determined. Is controlled by a three-way valve 86 which is a combustion gas flow control means.

The flow rate Ga of the combustion gas flowing through the three-way valve 86 toward the exhaust pipe 42 is represented by the product of the pressure difference ΔP and the opening area (opening amount) S of the third port through which the combustion gas passes. Therefore, the three-way valve 86 controls the combustion gas discharge pipe 73.
The valve is set so that the opening degree of the third port becomes smaller as the engine load Te is larger and the engine speed Ne is higher so that the flow rate Ga of the combustion gas introduced into the engine is constant irrespective of the fluctuation of the pressure difference ΔP. On the other hand, the valve body 86b is operated such that the smaller the engine load Te and the lower the engine speed Ne, the larger the opening of the third port.

In this way, the amount of intake air extracted from the intake pipe 14 becomes constant. In addition, if the extracted amount of intake air is set so as not to lower the engine output, air from the intake pipe 14 is supplied to the combustion heater 91 as combustion air regardless of the pressure fluctuation. In addition, there is no problem of output reduction.

Also, the combustion gas exhaust pipe 73 is connected to the communication passage 73a.
When the combustion type heater 91 communicates with the exhaust pipe 4 via the combustion gas discharge pipe 73,
In addition to the connection with the intake pipe 2, it is also connected with the intake pipe 14 via the series of passages 87. Therefore, the combustion type heater 91 is connected to the intake pipe 14 via a series of passages 87 in addition to the air supply pipe 71.

As a result, an excessive flow of combustion gas in the combustion type heater 91 can be prevented even at the time of supercharging, so that poor ignition occurs, or the air-fuel ratio becomes lean, and the flame becomes unstable, so that the flame becomes unstable. Does not stabilize combustion or cause lean misfire.

A series of passages 87, another series of parallel connection pipes 74 and communication passages 73a instead of a part 73b on the upstream side of the valve device 86 among the combustion gas discharge pipes 73, are provided. Although the combustion gas discharge side of the combustion type heater 91 may be connected to the intake pipe 14 via a passage, in order to simplify the description, here, a series of passages 87 including the communication passage 73a and the portion 73b will be described. Should be explained. <Second Embodiment> A second embodiment will be described with reference to FIG.

The engine 1A according to the second embodiment is
The engine 1A according to the first embodiment is different from the engine 1A in that the engine 1A does not have the three-way valve 86 and that the valve device 78 is used instead of the three-way valve 86 as the combustion gas flow control means. It is. Note that the valve device 78 linearly controls the flow rate of the combustion gas flowing therethrough, similarly to the three-way valve 86. Therefore, the different parts and the parts related thereto will be described, and the other same parts will be denoted by the same reference numerals as those in the drawings according to the first embodiment, and description thereof will be omitted.

In the engine 1 according to the first embodiment,
The parallel connection pipe 74 was connected to the combustion gas discharge pipe 73. On the other hand, in the second embodiment, the parallel connection pipe 74 is connected to the intake pipe 14 so that the parallel connection pipe 74 serves as a series of passages 87 according to the first embodiment. In other words, the combustion gas is treated as an intake-side exhaust pipe for introducing the combustion gas into the intake pipe 14, and this is indicated by reference numeral 87. The intake-side discharge pipe 87 is a pipe that connects the combustion gas discharge port 63 of the combustion heater 91 and the connection point C2.

Further, in the engine 1A, the opening 7 serving as an outlet port of the valve device 78 communicating with the combustion gas discharge port 65 is provided.
9b and the connection point C3 of the exhaust pipe 42 are connected by a pipe 73. This pipe 73 corresponds to the combustion gas discharge pipe 73 according to the first embodiment, and is connected to the intake-side discharge pipe 87. Is referred to as an exhaust side discharge pipe 73.

In the second embodiment, the valve device 78 as the combustion gas flow control means is a two-way valve. In this case, the expression of the three-way valve 86 in the contents of S104 and S105 in the flowchart of FIG. Is replaced with the valve device 78, so that the flowchart of FIG. 7 can be applied to the engine 1A according to the second embodiment. <Operation and Effect of Second Embodiment> In the case of the engine 1A according to the second embodiment, the same effect as that of the engine 1 is achieved. That is, regardless of the pressure fluctuation, the combustion type heater 9
1 can supply the intake air from the intake pipe 14 as combustion air, and does not cause a problem of output reduction. Further, even at the time of supercharging, it is possible to prevent excessive combustion gas flow in the combustion type heater 91. For this reason, there are no adverse effects such as poor ignition, a lean air-fuel ratio and unstable flame, resulting in unstable combustion or a lean misfire. <Others> In order for the catalyst included in the catalytic converter 39 to function effectively, the temperature of the catalyst needs to be at a certain level. Therefore, regardless of the pressure difference between the pressure in the intake pipe 14 and the pressure in the exhaust pipe 42, the opening of the valve device 78 and the three-way valve 86 on the exhaust side is maintained so that the catalyst temperature can be maintained at a temperature at which the catalyst can function effectively. It may be adjusted.

[0099]

As described above, the internal combustion engine having the combustion heater according to the present invention has the following effects, for example.

Even if the intake pressure is increased by the supercharger, excess air can be prevented from flowing into the combustion type heater. Also, when the internal combustion engine needs to increase its output, such as during supercharging, the combustion from the intake passage is performed. Even if the intake air is exhausted as the combustion air of the type heater, an excessive decrease in the supercharging pressure can be prevented, and thus a decrease in the output of the internal combustion engine can be suppressed.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view showing an operation state of the combustion type heater according to the first embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing another operation state of the combustion heater according to the first embodiment of the present invention.

FIG. 4 is a schematic sectional view of a three-way valve.

FIG. 5 is a diagram showing a map M1.

FIG. 6 is a diagram showing a map M2.

FIG. 7 is a flowchart for explaining a routine for executing the opening control of the three-way valve according to the present invention;

FIG. 8 is a schematic configuration diagram of a combustion heater according to a second embodiment of the present invention.

[Explanation of symbols]

1, 1A Engine (internal combustion engine) 3 Engine body 5 Intake device 7 Exhaust device 8 EGR device 10 Heater core 11 ECU (pressure difference obtaining means) 13 Air cleaner 14 Intake pipe (engine intake passage) 15 Turbocharger (supercharger) 15a Compressor 15b Turbine 19 Intercooler 22 Intake manifold 28 Exhaust manifold 30 EGR valve 37 Heater internal cooling water passage 37a Cooling water inlet 37b Cooling water outlet 39: Catalytic converter 40: Combustion cylinder 40a: Partition wall 42: Exhaust pipe (exhaust passage) 43: Outer wall 48: Combustion chamber 49: Intake pressure sensor 50: Electric water pump 51: Intake throttle valve 62: Air supply port 63: Combustion gas Outlet port 65: Combustion gas outlet port 71: Air supply pipe (air supply path) 73: Fuel Gas exhaust pipe, exhaust-side exhaust pipe (combustion gas exhaust path) 73a ... Communication path 73b ... Part of combustion gas exhaust pipe 73 74 ... Parallel connection pipe 78 ... Valve device (combustion gas flow control means) 79 ... Valve chamber 79a ... Opening 79b ... opening 80 ... valve body 81 ... EGR passage 82 ... actuator 86 ... valve device, three-way valve (combustion gas flow control means) 86a ... case body 86b ... valve body 86b1 ... stem 86b2 ... valve part 86b3 ... valve part 86c ... operation 86d: Opening hole 86e: Dividing plate 87: A series of passages, intake-side combustion / exhaust pipe 88: Fuel supply pipe 89: Fuel pump 90: Ventilation fan 91: Combustion heater 92: Motor 93: Housing 95: Air intake W ... heat medium circulation path W1 ... water pipe W2 ... water pipe W3 ... water pipe F ... flame Ar ... area indicating that the pressure difference is at the target pressure difference Pd1 ... pressure difference d2: Pressure difference Pd3: Pressure difference Pd4: Pressure difference C1: Location where the intake pipe 14 is connected to the air supply pipe 71 (location where the intake path is connected to the air supply path) C2: Connection where the intake pipe 14 is connected to the communication path 73a (The place where the intake passage is connected to the communication path) C3 ... the place where the exhaust pipe 42 and the combustion gas discharge pipe 73 are connected Ga ... the flow rate of the combustion gas flowing through the valve device 78 S ... the opening area (opening amount) ΔP ... the pressure difference Sp: internal space Ne: engine speed Te: engine load Ne1: engine speed Te1: engine load Ne2: engine speed Te2: engine load M1: map (index) M2: map

Claims (7)

[Claims] 1. A combustion type heater which burns an air-fuel mixture obtained by mixing fuel with air introduced from an engine intake passage, generates combustion gas, and raises the temperature of an engine-related element by utilizing heat of the combustion gas. A supercharger that pressurizes the air in the intake passage; an air supply path that supplies the air pressurized by the supercharger to the combustion heater; and a bypass that bypasses a cylinder of the internal combustion engine to exhaust the combustion gas. In an internal combustion engine having a combustion gas discharge passage discharging to a passage, a pressure difference obtaining unit for obtaining a pressure difference between a pressure in the intake passage and a pressure in the exhaust passage, and a pressure difference obtaining unit for obtaining a pressure difference. An internal combustion engine having a combustion-type heater, comprising: a combustion gas flow rate control unit that controls a flow rate of the combustion gas introduced into the combustion gas discharge path based on a pressure difference. 2. An internal combustion engine having a combustion type heater according to claim 1, wherein said combustion gas flow rate control means controls the flow rate of said combustion gas to be constant irrespective of the fluctuation of said pressure difference. 3. The combustion type heater according to claim 1, wherein the pressure difference obtaining means calculates and obtains the pressure difference from an engine speed and a load on the internal combustion engine. Having an internal combustion engine. 4. The pressure difference obtaining means detects the pressure difference by using a map which is an index for predicting the pressure difference and which indicates the pressure difference based on the engine speed and the load. An internal combustion engine having the combustion heater according to claim 1 or 2. 5. The method according to claim 1, wherein said combustion gas flow control means is a two-way valve or a three-way valve, and determines the degree of opening of these valves based on said pressure difference. An internal combustion engine having a combustion heater. 6. The combustion gas discharge passage and the intake passage communicate with each other through a communication passage, and the communication passage includes the three-way valve at a location where the communication passage is connected to the combustion gas discharge passage. An internal combustion engine having a combustion type heater. 7. The combustion type according to claim 6, wherein a point where the intake passage and the communication path are connected is downstream and near a point where the intake path is connected to the air supply path. An internal combustion engine having a heater.