WO2015163052A1

WO2015163052A1 - Cooling device for internal combustion engine

Info

Publication number: WO2015163052A1
Application number: PCT/JP2015/058294
Authority: WO
Inventors: 正和田畑
Original assignee: トヨタ自動車株式会社
Priority date: 2014-04-25
Filing date: 2015-03-19
Publication date: 2015-10-29
Also published as: JPWO2015163052A1

Abstract

A cooling device according to the present invention is equipped with: a container (112) having one gas inlet/outlet port; a cooler core (120) disposed inside the container (112); and a connection pipe (110) branching from an exhaust pipe (24) in an area between an exhaust valve and a catalyst and connecting the exhaust pipe (24) to the inlet/outlet port of the container (112). When V1 is the volume of the space between the branching point of the connection pipe (110) and a front end surface (122) of the cooler core (120) in the container (112), V2 is the volume of the container (112) past the front end surface (122) of the cooler core (120) as V2, and A is the ratio of the minimum pressure and maximum pressure indicated by the exhaust gas pressure when an internal combustion engine outputs its maximum torque, the container (112) and the connection pipe (110) are formed so as to satisfy the following relationship. V1/(V1 + V2) < 1 - A

Description

Cooling device for internal combustion engine

The present invention relates to a cooling device for an internal combustion engine, and more particularly to a cooling device that cools exhaust gas that becomes high temperature under high load.

During high-load operation of an internal combustion engine, the exhaust gas becomes hot, and adversely affects exhaust system components such as the catalyst and turbocharger turbine and wastegate valve. In order to prevent the deterioration and breakage of these parts due to high-temperature exhaust gas, various countermeasures have been proposed and put into practical use. One of them is to increase the fuel injection amount during high-load operation, as disclosed in Patent Document 1 below. According to this method, the exhaust gas can be cooled by the heat of vaporization when the fuel is vaporized. However, in this method, since fuel is used only for lowering the temperature of exhaust gas, deterioration of fuel consumption cannot be avoided.

Also, it has been studied to reduce the temperature of the exhaust gas by supplying cooling water to the exhaust system. However, in this method, the temperature of the exhaust gas is lowered in the low load operation rather than the high load operation. For this reason, the problem of deteriorating the activation of the catalyst at the time of starting, and the problem of reducing the acceleration response of the internal combustion engine with a turbocharger arise. Therefore, it can be said that the demerit during low-load operation is greater than the advantage obtained during high-load operation simply by arranging a heat exchanger in the exhaust passage.

The following Patent Document 2 discloses that a bypass passage that bypasses the heat exchanger disposed in the exhaust passage is provided, and the exhaust gas path is switched between the heat exchanger and the bypass passage by a valve. According to this technology, by controlling the valve according to the operating state of the internal combustion engine, exhaust gas is not passed through the heat exchanger during low load operation, but exhaust gas is passed through the heat exchanger only during high load operation. can do. However, in this case, a valve that is exposed to high-temperature exhaust gas is required to have high heat resistance, but high cost is required to satisfy such a requirement. Further, although the effect of lowering the temperature of the exhaust gas is increased as the load is higher, the cooling effect when the exhaust gas is passed through the heat exchanger becomes lower as the flow rate of the exhaust gas increases.

Japanese Unexamined Patent Publication No. 10-205375 Japanese Unexamined Patent Publication No. 2009-091918

It is preferable to use a heat exchanger as a means for lowering the temperature of the exhaust gas because it does not cause an extreme deterioration in fuel consumption as in the case of increasing the fuel injection amount. However, none of the techniques proposed in the prior art meet the requirement to increase the cooling capacity as the load on the internal combustion engine increases.

The present invention has been made in view of such problems, and an object of the present invention is to provide a cooling device having a self-adjusting function that automatically increases the cooling capacity in accordance with an increase in the load of the internal combustion engine. .

The cooling device according to the present invention includes a container having one gas inlet / outlet, a cooler core disposed inside the container, a branch from the exhaust passage in a section from the exhaust valve to the catalyst, and the exhaust passage and the inlet / outlet of the container. And a connecting pipe to be connected. The shape of the container may be cylindrical, bag-like, or more complicated as long as there is only one gas inlet / outlet. The cooler core is preferably a heat exchanger that cools the internal gas by heat exchange with other fluids. When the internal combustion engine to which the cooling device is applied includes a turbocharger, the connecting pipe preferably branches from the exhaust passage in a section from the exhaust valve to the turbocharger turbine.

In the cooling device according to the present invention, when the volume of the space from the branch point of the connecting pipe to the front end surface of the cooler core is V1, the volume of the container on the back side from the front end surface of the cooler core is V2, and the internal combustion engine outputs the maximum torque When the ratio between the lowest pressure and the highest pressure indicated by the exhaust pressure is defined as A, the container and the connecting pipe are configured to satisfy the following relationship. The following relationship is a condition in which exhaust gas flows into the cooling space in the container through the connecting pipe due to pressure pulsation in the exhaust passage, and the replacement efficiency of the gas in the cooling space increases as the load increases.
V1 / (V1 + V2) <1-A

The container and the connecting pipe are preferably such that the resonance frequency of the internal gas is greater than 0.5 times and less than 1.5 times the frequency of the pressure pulsation generated in the exhaust passage when the internal combustion engine outputs the maximum torque. Configured. This is a condition in which the resonance pressure in the container and the connecting pipe is synchronized with the pressure pulsation in the exhaust passage, and the inflow of exhaust gas into the cooling space and the exhaust of exhaust gas from the cooling space are efficiently repeated.

It is preferable that a marginal space is provided between the rear end surface of the cooler core and the container. By providing such a space on the opposite side of the gas inlet / outlet of the container across the cooler core, the exhaust gas reaches the inner part of the cooler core, and more efficient cooling of the exhaust gas by the cooler core becomes possible. . Here, when the volume of the cooler core is defined as V3, and the volume of the extra space provided between the rear end face of the cooler core and the container is defined as V4, the container and the connecting pipe are configured to satisfy the following relationship as well. Is more preferable. The following relationship is a condition for exhaust gas to reach the interior of the container through the cooling space at a high load, that is, a condition that can further improve the efficiency of replacing the gas in the cooling space.
(V1 + V3) / (V1 + V3 + V4) <1-A

According to the cooling device of the present invention, the exhaust gas flows into the container through the connecting pipe by the pressure pulsation in the exhaust passage, and the exhaust gas is cooled by the cooler core in the container. The efficiency of gas replacement in the cooling space is low during low-load operation where the ratio between the minimum and maximum exhaust pressure is small, and increases as the ratio between the minimum and maximum exhaust pressure increases as the load increases. Go. That is, according to the cooling device according to the present invention, a self-adjusting function is realized in which the cooling capacity automatically increases as the load of the internal combustion engine increases.

It is a figure which shows the internal combustion engine with a turbocharger provided with the cooling device of Embodiment 1 of this invention. It is a figure which shows the attachment position of a cooling device. It is a graph which shows the pulsation of the pressure which arises in an exhaust pipe. It is a graph which shows the highest pressure and the lowest pressure of exhaust pressure. It is a figure which shows the detail of the cooling device of Embodiment 1 of this invention. It is a graph which shows the effect of the cooling device of Embodiment 1 of the present invention. It is a figure which shows the internal combustion engine with a turbocharger provided with the cooling device of Embodiment 2 of this invention. It is a figure which shows the detail of the cooling device of Embodiment 2 of this invention. It is a figure which shows side by side the pulsation of the pressure which arises in an exhaust pipe, and the resonance of the air column in a cooling device. It is a figure which shows the relationship between the length of an expansion pipe, exhaust gas temperature, and the resonant frequency of the gas inside a cooling device. It is a figure which shows the relationship between the length of an expansion pipe, and a cooling effect. It is a figure which shows the internal combustion engine with a turbocharger provided with the cooling device of Embodiment 3 of this invention. It is a figure which shows the internal combustion engine with a turbocharger provided with the cooling device of Embodiment 4 of this invention. It is a figure which shows the internal combustion engine with a turbocharger provided with the cooling device of Embodiment 5 of this invention. It is a figure which shows the internal combustion engine with a turbocharger provided with the cooling device of Embodiment 6 of this invention. It is a figure which shows the natural intake internal combustion engine provided with the cooling device of Embodiment 7 of this invention. It is a figure which shows other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in the embodiment shown below, when referring to the number of each element, quantity, quantity, range, etc., unless otherwise specified or clearly specified in principle, the reference However, the present invention is not limited to this number. The configurations described in the following embodiments are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle. In the drawings, the same or similar parts are denoted by the same or similar reference numerals.

Embodiment 1 FIG.
FIG. 1 is a diagram showing an internal combustion engine 2 with a turbocharger provided with a cooling device 101 according to Embodiment 1 of the present invention. The internal combustion engine 2 is a four-stroke one-cycle engine and is an in-line four-cylinder engine in which four cylinders are provided in series. However, the internal combustion engine 2 may be configured as a spark ignition engine, or may be configured as a compression self-ignition engine.

The cylinder head 4 of the internal combustion engine 2 is formed with an intake port 8 and an exhaust port 10 leading to the combustion chamber 6. An intake valve 12 is provided between the combustion chamber 6 and the intake port 8, and an exhaust valve 14 is provided between the combustion chamber 6 and the exhaust port 10. An intake pipe 16 is connected to the intake port 8, and an exhaust pipe 24 is connected to the exhaust port 10. The intake port 8 and the intake pipe 16 are combined to form an intake passage, and the exhaust port 10 and the exhaust pipe 24 are combined to form an exhaust passage. A compressor 32 of a turbocharger 30 is attached to the intake pipe 16, and a turbine 34 of the turbocharger 30 is attached to the exhaust pipe 24. An intercooler 20 is provided downstream of the compressor 32 in the intake pipe 16, and a throttle valve 18 is provided downstream of the intercooler 20. A catalyst 26 for purifying the exhaust gas is provided downstream of the turbine 34 in the exhaust pipe 24. The internal combustion engine 2 includes an actuator such as a fuel injection device, a variable valve timing mechanism, and an ignition device, and various sensors, which are omitted in FIG.

The cooling device 101 of Embodiment 1 is attached upstream of the turbine 34 in the exhaust pipe 24. The cooling device 101 includes a water-cooled cooler core (hereinafter, water-cooled cooler) 120. FIG. 2 is a diagram showing in detail the mounting position of the cooling device 101 in the exhaust pipe 24. The exhaust pipe 24 is attached to the cylinder head 4 and includes an exhaust manifold connected to the exhaust ports of the cylinders # 1, # 2, # 3, and # 4. A hole 40 is formed in the junction where the four branch pipes of the exhaust manifold merge, and the cooling device 101 is attached to the hole 40.

FIG. 3 is a graph showing changes in the exhaust pipe pressure acting on the position of the hole 40 depending on the crank angle. The exhaust pipe pressure shown in the graph is an absolute pressure. In the graph, changes in the exhaust pipe pressure under various intake pipe pressures (pressures downstream of the throttle valve) are drawn with different line types. As shown in this graph, the exhaust pipe pressure periodically increases and decreases. Since the internal combustion engine 2 is an in-line four-cylinder engine, the pulsation cycle of the exhaust pipe pressure is 180 degrees. When the exhaust pipe pressure changes from the lowest pressure to the highest pressure, the exhaust gas flows into the cooling device 101 from the hole 40, and when the exhaust pipe pressure changes from the highest pressure to the lowest pressure, the cooling device 101 enters the hole 40. Exhaust gas is discharged. At this time, the inflow amount and the exhaust amount of exhaust gas per cycle increase as the amplitude of the exhaust pipe pressure pulsation increases. The minimum and maximum exhaust pipe pressures both increase as the intake pipe pressure increases, and the pulsation amplitude increases as the intake pipe pressure increases. Therefore, when the intake pipe pressure is the highest, the inflow amount and the exhaust amount per cycle of the exhaust gas are maximized, and the inflow amount and the exhaust amount decrease as the intake pipe pressure decreases.

FIG. 4 is a graph showing the change of the exhaust pipe pressure acting on the position of the hole 40 when the intake pipe pressure is the highest, depending on the crank angle. Since the intake pipe pressure is proportional to the air flow rate, this graph shows a change in the exhaust pipe pressure at the maximum load, that is, when the internal combustion engine 2 outputs the maximum torque. The magnitude of the torque output from the internal combustion engine 2 depends on the rotational speed of the internal combustion engine 2, but the maximum torque in this specification means the maximum torque at all the rotational speeds. Here, as shown in the graph, the maximum exhaust pipe pressure at the maximum torque is defined as “B”, and the minimum exhaust pipe pressure at the maximum torque is defined as “C”. However, the values of B and C are not obtained on-board, but are values obtained in advance in a test. In the present invention, the ratio of C to B is defined as “A”. As can be seen from the graph of FIG. 3, the ratio of the minimum pressure to the maximum pressure of the exhaust pipe pressure is close to 1 when the intake pipe pressure is low, and decreases as the intake pipe pressure increases. Therefore, A defined as above is the minimum value of the ratio of the minimum pressure to the maximum pressure of the exhaust pipe pressure. The cooling device 101 according to the first embodiment is designed based on the value A.

FIG. 5 is a diagram showing details of the cooling device 101 of the first embodiment. The cooling device 101 includes a container 112 including a water-cooled cooler 120 and a connection pipe 110 that branches from the exhaust pipe 24 at the hole 40 and connects the container 112 to the exhaust pipe 24. The water cooling cooler 120 is a heat exchanger that cools the exhaust gas in the container 112 by heat exchange with cooling water. The structure of the water-cooled cooler 120 is not limited, and for example, a structure used in an EGR cooler can be used. A water supply pipe that supplies cooling water to the water-cooled cooler 120 and a drain pipe that discharges cooling water from the water-cooled cooler 120 are connected to the container 112, but these are not shown. In FIG. 5, a margin space is provided between the cooling space cooled by the water-cooled cooler 120 and the container 112, but this margin space may not be provided.

According to the configuration shown in FIG. 5, the exhaust gas flowing through the exhaust pipe 24 is pushed into the connection pipe 110 by the pulsation of the pressure of the exhaust pipe 24 and further pushed into the container 112. At this time, whether or not the exhaust gas reaches the cooling space cooled by the water-cooled cooler 120 depends on the relationship between the magnitude of the pulsation of the exhaust pipe pressure and the structure of the cooling device 101. Here, the volume from the position of the hole 40 that is the branch point of the connecting pipe 110 to the front end surface 122 of the water-cooled cooler 120 is “V1”, and the volume of the container 112 on the back side from the front end surface 122 of the water-cooled cooler 120 is “V2”. It is defined as However, V2 includes the volume of the space in which the exhaust gas in the water-cooled cooler 120 flows (effective cooling volume), but does not include the volume of the portion of the water-cooled cooler 120 through which the cooling water flows. When V1 and V2 defined here and A defined earlier are used, the condition for the exhaust gas to reach the water-cooled cooler 120 is expressed by the following relational expression (1).
V1 / (V1 + V2) <1-A Formula (1)

Equation (1) is a condition under which the exhaust gas can reach the water-cooled cooler 120 when the internal combustion engine 2 outputs the maximum torque. As the value on the left side is smaller than the value on the right side, the exhaust gas can reach deeper in the water-cooled cooler 120. The value on the right side is determined by the specifications of the internal combustion engine 2, and the value on the left side is determined by the structure of the cooling device 101. The cooling device 101 is configured so that the relationship of the expression (1) is satisfied.

FIG. 6 is a graph showing the effect obtained by configuring the cooling device 101 as described above. The horizontal axis of the graph is the torque of the internal combustion engine 2, and the vertical axis is the outlet temperature of the turbine 34. The temperature described as having a cooler in the graph is a temperature when the cooling device 101 is provided. On the other hand, the temperature indicated as “no cooler” is a temperature when the cooling device 101 is not provided. As can be seen from this graph, the decrease in the turbine outlet temperature due to the provision of the cooling device 101 is almost zero in the low load region, but increases as the load increases. This is due to the following effects. First, in a low load region where the pulsation of the exhaust pipe pressure is small, the exhaust gas does not reach the water-cooled cooler 120 or does not enter the water-cooled cooler 120 even if it reaches. However, when the load increases and the pulsation of the exhaust pipe pressure increases, the exhaust gas enters into the water-cooled cooler 120. And the temperature fall of exhaust gas by cooling with the water cooling cooler 120 becomes large, so that the reach distance of the exhaust gas in the water cooling cooler 120 becomes long. As a result, a cooling effect corresponding to the load as shown in the graph can be obtained.

As described above, the cooling device 101 of the first embodiment is provided with a self-adjusting function that automatically increases the cooling capacity when the load of the internal combustion engine 2 increases. Thus, during high load operation, the exhaust gas temperature can be reduced to protect the exhaust system components. Further, since the exhaust gas temperature is not unnecessarily lowered during low load operation, it is possible to prevent the acceleration response of the turbocharger 30 from deteriorating and the activation delay of the catalyst 26 at the start.

Embodiment 2. FIG.
FIG. 7 is a diagram showing the turbocharged internal combustion engine 2 provided with the cooling device 102 according to the second embodiment of the present invention. The cooling device 102 according to the second embodiment is configured by adding an expansion pipe 130 to the cooling device 101 according to the first embodiment.

FIG. 8 is a diagram showing details of the cooling device 102 according to the second embodiment. The cooling device 102 according to the second embodiment includes a connection pipe 110, a container 112, and an expansion pipe 130. The expansion tube 130 is attached to the side of the container 112 opposite to the side to which the connection tube 110 is connected. The distal end (that is, the end opposite to the side attached to the container 112) 132 of the expansion tube 130 is closed. In the second embodiment, one structure including the container 112 and the expansion tube 130 corresponds to the “container” in the present invention. Although not shown, valves may be provided in the connecting pipe 110 and the extension pipe 130 to restrict the inflow of exhaust gas to these and the exhaust gas from them.

By providing the expansion pipe 130 in the container 112, the volume of the margin space behind the water-cooled cooler 120 viewed from the hole 40 is increased. If the marginal space behind the water-cooled cooler 120 is large, the exhaust gas easily reaches the back of the water-cooled cooler 120 correspondingly. As the exhaust gas reaches deeper in the water-cooled cooler 120, the efficiency of replacing the gas in the water-cooled cooler 120 increases, and the cooling effect of the exhaust gas by the water-cooled cooler 120 increases. Here, the effective cooling volume of the water-cooled cooler 120 (the volume of the space in which the exhaust gas in the water-cooled cooler 120 circulates) is “V3”, and the volume of the marginal space from the rear end surface 124 of the water-cooled cooler 120 to the tip 132 of the expansion pipe 130. Is defined as “V4”. The sum of V3 and V4 corresponds to V2 defined above. When V3 and V4 defined here and A and V1 defined above are used, the condition for the exhaust gas to reach the margin space behind the water-cooled cooler 120 is expressed by the following relational expression (2).
(V1 + V3) / (V1 + V3 + V4) <1-A (2)

Equation (2) is a condition that allows the exhaust gas to reach the marginal space behind the water-cooled cooler 120 when the internal combustion engine 2 outputs the maximum torque. As the value on the left side is smaller than the value on the right side, the exhaust gas can reach the back of the marginal space, that is, near the tip 132 of the expansion tube 130. The value on the right side is determined by the specifications of the internal combustion engine 2, and the value on the left side is determined by the structure of the cooling device 102. The cooling device 102 is configured so that the relationship of the expression (2) is satisfied.

Incidentally, in a tubular (or bag-like) structure such as the cooling device 102, the internal gas vibrates at a resonance frequency (natural frequency) determined by its shape and temperature. FIG. 9 is a diagram showing the pulsation of the pressure generated in the exhaust pipe 24 and the resonance of the air column in the cooling device 102 side by side. The lower graph in FIG. 9 shows the change in turbine inlet pressure (exhaust pipe pressure) depending on the crank angle. The frequency of the pulsation of the exhaust pipe pressure drawn in the graph can be calculated by “frequency = output rotational speed × number of cylinders / 2” in a 4-cycle 1-stroke engine. For example, if the output rotational speed is 3400 rpm, the internal combustion engine 2 is an in-line four-cylinder engine, so the frequency is calculated to be about 113 Hz.

In the upper part of FIG. 9, when the resonance frequency matches the pulsation frequency of the exhaust pipe pressure, when the resonance frequency is higher than the pulsation frequency of the exhaust pipe pressure, and when the resonance frequency is lower than the pulsation frequency of the exhaust pipe pressure. For each case, the waveform of the pressure due to resonance of the air column in the cooling device 102 is shown. When the resonance frequency matches the pulsation frequency of the exhaust pipe pressure, that is, when one cycle of the exhaust pulsation matches one wavelength of the oscillating air column (case 1), the exhaust pulsation peak coincides with the resonance peak. The exhaust pulsation trough coincides with the resonance trough. Therefore, in this case, inflow of the exhaust gas into the cooling device 102 and discharge of the exhaust gas from the cooling device 102 are repeated most efficiently.

However, when the resonance frequency is smaller than the frequency of the exhaust pipe pressure pulsation, that is, when one cycle of the exhaust pulsation is shorter than one wavelength of the vibrating air column (case 2), the exhaust pulsation peak and the resonance peak However, the resonance valley shifts to the retard side with respect to the exhaust pulsation valley. When the resonance valley overlaps the exhaust pulsation peak as in the case 2, the exhaust gas is hardly discharged from the cooling device 102 to the exhaust pipe 24. Therefore, in order for the exhaust gas to be discharged from the cooling device 102, it is necessary that a resonance valley has arrived before the exhaust pulsation peak arrives. For this purpose, the resonance frequency needs to be larger than ½ times the pulsation frequency of the exhaust pipe pressure.

When the resonance frequency is higher than the frequency of the exhaust pipe pressure pulsation, that is, when one cycle of the exhaust pulsation is longer than one wavelength of the vibrating air column (case 3), the exhaust pulsation peak and the resonance peak However, the resonance valley shifts to the advance side with respect to the exhaust pulsation valley. Even when the resonance valley overlaps the exhaust pulsation peak as in the case 3, the exhaust gas is hardly discharged from the cooling device 102 to the exhaust pipe 24. Therefore, in order for the exhaust gas to be discharged from the inside of the cooling device 102, it is necessary that the resonance valley arrive after the exhaust pulsation peak arrives. For this purpose, the resonance frequency needs to be smaller than 3/2 times the pulsation frequency of the exhaust pipe pressure.

As described above, the resonance frequency of the gas inside the cooling device 102 is greater than 0.5 times and less than 1.5 times the frequency of the pulsation of the exhaust pipe pressure when the internal combustion engine 2 outputs the maximum torque. desirable. This also applies to the cooling device 101 of the first embodiment. It is desirable that the shapes of the connecting pipe 110 and the container 112 are adjusted so that the above-described condition regarding the resonance frequency is satisfied. On the other hand, according to the structure of the cooling device 102, the resonance frequency of the internal gas can be adjusted by the length of the expansion pipe 130. FIG. 10 is a graph showing the relationship between the length of the expansion pipe 130, the temperature of the exhaust gas, and the resonance frequency of the gas inside the cooling device 102. The temperature of the exhaust gas inside the cooling device 102 is cooled to about 100 ° C. by the cooling by the water cooling cooler 120. Therefore, assuming that the temperature of the exhaust gas is 100 ° C., the length of the expansion pipe 130 is determined so that the resonance frequency falls within the range of 0.5 to 1.5 times the pulsation frequency of the exhaust pipe pressure. Good. More preferably, the length of the expansion pipe 130 is set to the pulsation frequency of the exhaust pipe pressure as much as possible so that the resonance frequency is within the above-described desired range at the same time that the relationship of the expression (2) is satisfied. Adjusted to match.

FIG. 11 is a graph showing the relationship between the length of the expansion tube 130 and the cooling effect. In the example shown in this graph, the cooling effect of the cooling device 102, that is, the amount of decrease in the temperature of the exhaust gas by the cooling device 102 becomes maximum when the length of the expansion pipe 130 is about 830 mm, and even if longer than that, Moreover, even if it is shorter than that, the cooling effect of the cooling device 102 is reduced. Therefore, in the example shown in this graph, it can be seen that 830 mm is the most desirable length of the expansion tube 130. The length of 830 mm is a length that satisfies the relationship of the expression (2) and at the same time the resonance frequency falls within the range of 0.5 to 1.5 times the pulsation frequency of the exhaust pipe pressure.

As described above, according to the cooling device 102 of the second embodiment, not only a self-adjusting function that automatically increases the cooling capacity when the load of the internal combustion engine 2 increases but also the cooling capacity of the water cooling cooler 120 is provided. Can be used more effectively.

Embodiment 3 FIG.
FIG. 12 is a diagram showing the turbocharged internal combustion engine 2 provided with the cooling device 103 according to the third embodiment of the present invention. The cooling device 103 according to the third embodiment includes an expansion container 140 having a throttle instead of the cylindrical expansion tube 130 provided in the cooling device 102 according to the second embodiment. In the second embodiment, one structure including the container 112 and the expansion container 140 corresponds to the “container” in the present invention. If it is bowl-shaped like this expansion container 140, the volume of the extra space behind the water-cooled cooler 120, that is, V4 in equation (2) can be increased. In the case of a configuration including the expansion container 140 with a throttle, the resonance frequency of the gas inside the cooling device 103 can be adjusted by the volume of the expansion container 140 and the diameter of the throttle. Therefore, in the cooling device 103 of the third embodiment, the volume and throttle diameter of the expansion container 140 are adjusted so that the resonance frequency falls within the range of 0.5 to 1.5 times the pulsation frequency of the exhaust pipe pressure. The

Embodiment 4 FIG.
FIG. 13 is a diagram showing the turbocharged internal combustion engine 2 including the cooling device 104 according to the fourth embodiment of the present invention. The cooling device 104 of the fourth embodiment has the same structure as the cooling device 103 of the third embodiment. However, while the cooling device 103 according to the third embodiment is connected to the exhaust pipe (more specifically, the collection portion of the exhaust manifold), the cooling device 104 according to the fourth embodiment is provided for each cylinder. Connected to the exhaust port 10. More specifically, a passage branched from the exhaust port 10 is formed in the cylinder head 4, and the cooling device 104 is attached to the passage. For this reason, only the pulsation of the pressure of the exhaust gas discharged from one cylinder acts on the cooling device 104. The period of pressure pulsation is one cycle, that is, 720 degrees. In the cooling device 104 of the fourth embodiment, the resonance frequency of the gas inside the cooling device 104 falls within the range of 0.5 to 1.5 times the frequency of the pressure pulsation with respect to the pressure pulsation having a period of 720 degrees. In this way, the volume and the diameter of the expansion container 140 are adjusted. According to the cooling device 104 of the fourth embodiment, the temperature of the exhaust gas in the exhaust port 10 can be lowered to cool the exhaust valve 14 in a thermally severe environment.

Embodiment 5 FIG.
FIG. 14 is a diagram showing the turbocharged internal combustion engine 2 including the cooling device 105 according to the fifth embodiment of the present invention. The cooling device 105 of the fifth embodiment has the same structure as the cooling device 103 of the third embodiment. However, the cooling device 105 of the fifth embodiment is attached upstream of the wastegate valve 38 in the bypass passage 36 that bypasses the turbine 34. The cooling device 105 according to the fifth embodiment is particularly provided for cooling the waste gate valve 38. The bypass passage 36 to which the cooling device 105 is attached has the same pressure pulsation as that of the upstream exhaust pipe 24, but the exhaust gas flow rate is small. For this reason, according to the cooling device 105 of the fifth embodiment, a high cooling effect can be obtained for the exhaust gas flowing through the bypass passage 36.

Embodiment 6 FIG.
FIG. 15 is a diagram showing the turbocharged internal combustion engine 2 provided with the cooling device 106 according to the sixth embodiment of the present invention. The entire cooling device 106 according to the sixth embodiment is built in the cylinder head 4. Specifically, a passage branched from the exhaust port 10 is formed in the cylinder head 4, and the water-cooled cooler 120 is accommodated in the passage. Also in the sixth embodiment, the cooling device 106 is configured to satisfy at least the relationship of the expression (1). Further, a marginal space may be provided behind the water-cooled cooler 120 as in the embodiment 2-5. The cooling device 106 according to the sixth embodiment can effectively cool the exhaust valve 14 as the cooling device 104 according to the fourth embodiment.

Embodiment 7 FIG.
FIG. 16 is a diagram showing a naturally aspirated internal combustion engine 202 including the cooling device 107 according to the seventh embodiment of the present invention. The mounting position of the cooling device 107 according to the seventh embodiment is the upstream of the catalyst 26 in the exhaust pipe 24, more specifically, the section from the exhaust manifold assembly to the catalyst 26. The self-adjusting function of the cooling capacity of the cooling device 107 is also effective for the naturally aspirated internal combustion engine 202. In FIG. 16, the cooling device 107 has the same structure as the cooling device 103 of the third embodiment, but has the same structure as the cooling device 101 of the first embodiment and the cooling device 102 of the second embodiment. It can also be taken. Further, as in the fourth and sixth embodiments, the cooling device 107 can be attached to the exhaust port for each cylinder.

Other embodiments.
FIG. 17 is a diagram illustrating a modification of the cooling device 103 according to the third embodiment. In this modification, a branch pipe 136 that branches from the expansion pipe 130 is provided. The tip of the branch pipe 136 is closed. As in this example, the marginal space behind the water-cooled cooler 120 may have a complicated shape. Further, instead of providing a dedicated cooling device, the EGR cooler of the EGR device can also be used as a cooling device. By closing the EGR valve, the EGR pipe can function like the expansion pipe of the third embodiment.

The cooling medium used in the cooling mechanism is not limited to cooling water. A heat exchanger using air as a cooling medium can also be used as the cooler core. Moreover, as a cooling method, forced cooling from the outside of the container by wind generated by a fan may be used, or natural cooling may be performed by diffusion of heat by a radiator. In the cooling device, condensed water may be generated as the exhaust gas is cooled. Therefore, although not shown in Embodiment 1-7, it is desirable that the cooling device is provided with a drainage facility (for example, a drainage pipe and a valve) that discharges condensed water to the outside. For example, if it is the cooling device 101 of Embodiment 1, a drainage equipment can be attached to the bottom of the container 112. With the cooling device 102 of the second embodiment, a drainage facility can be attached to the tip 132 of the expansion pipe 130. In the cooling device 103 according to the third embodiment, a drainage facility can be attached to the bottom of the expansion container 140.

The cooling device according to the present invention can be applied not only to an in-line engine but also to other multi-cylinder engines such as a V-type engine and a horizontally opposed engine. Moreover, the cooling device according to the present invention can be applied to an engine that performs explosion at unequal intervals or a single cylinder engine. The cooling device according to the present invention can also be applied to a two-stroke one-cycle engine.

2 Internal combustion engine 4 Cylinder head 6 Combustion chamber 10 Exhaust port 14 Exhaust valve 24 Exhaust pipe 26 Catalyst 34 Turbine 40

Hole

101, 102, 103, 104, 105, 106, 107 Cooling device 110 Connection pipe 112 Container 120 Water-cooled cooler (cooler core)
130 Expansion tube 140 Expansion container

Claims

A container having one gas inlet and outlet;
A cooler core disposed inside the container;
A branch pipe branched from the exhaust passage in the section from the exhaust valve to the catalyst, and connecting the exhaust passage and the inlet / outlet of the container,
The cooling device for an internal combustion engine, wherein the container and the connection pipe are formed to satisfy the following relationship.
V1 / (V1 + V2) <1-A
Here, V1 is the volume of the space from the branch point of the connecting pipe to the front end surface of the cooler core, V2 is the volume of the container on the back side of the front end surface of the cooler core, and A is the maximum torque of the internal combustion engine. Is the ratio of the lowest pressure to the highest pressure indicated by the exhaust pressure.
In the container and the connecting pipe, the resonance frequency of the internal gas is greater than 0.5 times and less than 1.5 times the frequency of pressure pulsation generated in the exhaust passage when the internal combustion engine outputs maximum torque. The cooling apparatus for an internal combustion engine according to claim 1, wherein the cooling apparatus is configured as described above.
3. The cooling device for an internal combustion engine according to claim 1, wherein a marginal space is provided between a rear end surface of the cooler core and the container.
The cooling device for an internal combustion engine according to claim 3, wherein the container and the connection pipe are configured to satisfy the following relationship.
(V1 + V3) / (V1 + V3 + V4) <1-A
Here, V3 is the volume of the cooler core, and V4 is the volume of the margin space provided between the rear end surface of the cooler core and the container.
The internal combustion engine comprises a turbocharger;
The cooling of the internal combustion engine according to any one of claims 1 to 4, wherein the connection pipe branches from the exhaust passage in a section from the exhaust valve to a turbine of the turbocharger. apparatus.