JPS63198715A - Cooling device for exhaust manifold - Google Patents

Abstract

PURPOSE:To introduce cooling air to an air flow passage and cool a division separating an exhaust manifold easily and properly by forming the air flow passage within the division and making the passage continuous to an air intake passage at the downstream of a throttle valve via a bypass passage. CONSTITUTION:An exhaust turbocharger 2 comprises an exhaust turbine 13 of twin entry type, and has each pair of exhaust scroll chambers 40a and 40b and exhaust inflow passages 14a and 14b. On the other hand, an exhaust manifold 15 has a pair of manifold mains 41a and 41b and a pair of exhaust outlets 43a and 43b separated from each other with a division 42. In the aforesaid constitution, an air flow passage 44 is formed within the division 42. And the inlet of the air flow passage 44 is connected to an air intake duct 10 via a bypass passage 22, and the outlet thereof is connected to an idling speed control valve 19 via the bypass passage 22. According to the aforesaid constitution, the air cooled with an inter-cooler 9 is made to flow to an air flow passage 44, thereby cooling the division 42 effectively.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a cooling device for an exhaust manifold.

[Conventional technology]

A twin-entry exhaust turbocharger having a pair of exhaust scroll chambers is known. In this exhaust turbocharger, each exhaust scroll chamber is connected to a cylinder group that does not cause exhaust interference with each other. Therefore, the exhaust manifold used in such a twin-entry exhaust turbocharger has a pair of manifold clusters connected to cylinder groups that do not interfere with each other's exhaust emissions, and is further connected to each manifold cluster and separated from each other by a partition wall. It has a pair of exhaust gas outlets. These exhaust gas outlets are respectively connected to each exhaust scroll chamber.

By the way, in such an exhaust manifold, there is no place for heat to escape from the partition wall that separates the exhaust gas outlet, so the temperature of the partition wall increases excessively, resulting in thermal distortion in the partition wall and the connection between the exhaust manifold and the exhaust turbocharger. This causes the problem of exhaust gas leaking from the parts. In order to solve this problem, an internal combustion engine is known in which a cooling water passage is formed in the partition wall of the exhaust manifold so that the partition wall is cooled by engine cooling water (see Japanese Utility Model Application No. 112030/1983). ).

[Problem that the invention seeks to solve]

However, when attempting to cool the bulkhead with engine cooling water in this manner, there is a problem in that the cooling water becomes the color of the VFJ ring.

[Means for solving problems]

In order to solve the above problems, the present invention provides an internal combustion engine in which the exhaust manifold has a pair of exhaust gas outlets separated from each other by a partition wall, in which an air flow passage is formed in the partition wall, and air flows from the compressor of the exhaust turbocharger. A bypass passage is branched from the intake passage leading to the throttle valve, and the bypass passage is connected to the intake passage downstream of the throttle valve via an airflow passage.

〔Example〕

Referring to FIG. 1, reference numeral 1 indicates an engine main body, and reference numeral 2 indicates an exhaust turbocharger. The air inlet 4 of the compressor 3 of the exhaust turbocharger 2 is connected to an air cleaner 6 via an air flow meter 5, and the air discharge lower of the compressor 3 of the exhaust turbocharger 2 is connected to an intake duct 8, an intercooler 9, an intake duct 10, and a surge tank. 11 to an intake branch pipe 12. On the other hand, the exhaust inlet passage 14 of the exhaust turbine 13 of the exhaust turbocharger 2 is connected to the air manifold 15, and the exhaust outlet passage 16 of the exhaust turbine 13 of the exhaust turbocharger 2 is communicated with the atmosphere. The exhaust inflow path 14 and the exhaust outflow path 16 are connected via an exhaust bypass path 17.
Waste gate valve 17a that controls boost pressure within 7
will be provided.

On the other hand, a throttle valve 18 is arranged in the intake duct 10, and an idling speed control valve 19 is arranged in the surge tank 11 downstream of the throttle valve 18. This idling speed control valve 19 includes a valve body 20 for flow rate control, and a valve body 20 for controlling the flow rate.
It consists of an actuator 21 that controls 0. A bypass passage 22 branches off from the intake duct 10 between the intercooler 9 and the throttle valve 18, and this bypass passage 22 is connected to the idling speed control valve 19 after passing through the exhaust manifold 15. Idle speed control valve 19 is connected to electronic control unit 30.

The electronic control unit 30 consists of a digital computer with ROMs interconnected by a bidirectional bus 31.
(read only memory) 32, RAM (random access memory) 33, CPU (microprocessor) 3
4 and I10 ports (with output capo-135).

The throttle valve 18 is connected to a throttle switch 23 that detects that the throttle valve 18 is in the idling position, and a detection signal from the throttle switch 23 is input to the I10 boat 35. The input boat 35 also includes a rotation speed sensor 3 that generates an output pulse representing the engine rotation speed N.
6 is connected, and the I10 port 35 is connected to the actuator 2 of the idling speed control valve 19 via the drive circuit 37.
Connected to 1.

This actuator 21 is formed by, for example, a stem motor. When it is determined from the detection signal of the throttle sensor 23 that the engine is idling, the bypass passage 2 is opened so that the engine speed N becomes a predetermined speed.
The amount of intake air supplied from 2 to surge tank 11 is controlled by idling speed control valve 19. When the throttle valve 18 is opened, the idling speed control is stopped, but the valve body 20 is maintained at the opening degree that it was when the idling speed control was stopped. Air continues to be supplied. That is, air is constantly circulating in the bypass passage 22.

FIG. 2 shows the exhaust manifold 15 and exhaust turbine 13 of the exhaust turbocharger 2 of FIG. The exhaust turbocharger 2 is a twin entry type exhaust turbine 13
A pair of exhaust scroll chambers 40a and 40b;
Each exhaust scroll chamber 40a.

40b are provided.

On the other hand, the exhaust manifold 15 has a pair of manifold collection parts 41a and 4 connected to cylinder groups that do not interfere with each other in exhaust gas.
1b, and the exhaust manifold 15 further has a pair of exhaust gas outlets 43a, 43b connected to each manifold gathering portion 41a, 41b and separated by a partition 42. Each of these exhaust gas outflow ports 43a, 43b is connected to a corresponding exhaust inflow path 14a, 14b, respectively. As shown in FIGS. 2 and 3, an air flow passage 44 is provided within the bulkhead 42.
is formed. Air flow passage 440 inlet 45 is connected to intake duct 1-10 via bypass passage 22 (FIG. 1), and outlet 46 of air flow passage 44 is connected via bypass passage 22 to idle speed control valve 19. . As mentioned above, air is constantly circulating in the bypass passage 22,
Therefore, the air flow in the 1ffi path 44 is from the inlet 45 to the outlet 46.
Air is constantly flowing towards. Moreover, the bypass passage 22
The air sent inside is the air cooled by the intercooler 9. Therefore, the partition wall 42 is constantly cooled by the cooling air, and thus thermal distortion can be prevented from occurring in the partition wall 42.

FIG. 4 shows another embodiment. In this embodiment, the air flow passage 44 is formed to surround the exhaust gas outlets 43a, 43b. Therefore, in this embodiment, the exhaust manifold 15
The flange part 1 is attached to the exhaust turbocharger 2.
5a as a whole is cooled, and thus the mounting is performed on the flange portion 15a.
It is possible to prevent the occurrence of thermal distortion as a whole.

FIG. 5 shows yet another embodiment. In this embodiment, an electromagnetic switching valve 24 is provided, which is connected to the idle speed control valve 19 via an air flow passage 44 of the exhaust manifold 15.

The air flow passage 44 is selectively connected to the intake duct 10 downstream of the intercooler 9 via the bypass passage 22a or to the intake duct 8 upstream of the ink cooler 9 via the bypass passage 22b by the switching action of the electromagnetic switching valve 24. .

This electromagnetic switching valve 24 is connected to an I10 boat 35 via a drive circuit 38. In this embodiment, a water temperature sensor 25 that generates an output voltage proportional to the engine cooling water temperature is further attached to the engine body 1, and this output voltage is connected to the I10 port 35 via an AD converter 39. In addition, the air flow meter 5 generates an output voltage proportional to the intake air IQ,
This output voltage is applied to I10 port 3 via AD converter 40.
Connected to 5. Further, a starter switch 41 for driving the starter motor is connected to the I10 boat 35.

Next, the operation of the embodiment shown in FIG. 5 will be explained with reference to FIG. Note that the switching valve control routine shown in FIG. 6 is performed by interruption at regular intervals. Referring to FIG. 6, first, it is determined whether or not a start flag, which is set when the starter motor is activated, is set. If the starting flag is not set to Sera 1--, the process proceeds to step 51, where it is determined whether the starter switch 41 is on. If it is on, the process proceeds to step 52 to set the start flag for a certain period of time, for example - minutes, and then proceeds to step 53.

Therefore, after the starter motor operates, the steering knob 5
Proceed to Ste Nob 53 from 0. In step 53, the electromagnetic switching valve 24 is turned on, and as a result, the bypass passage 22 is connected to the intake duct 8 via the bypass passage 22b.

Therefore, at this time, high-temperature air that has not been cooled by the intercooler 9 is supplied into the surge tank 11, thus promoting vaporization of the fuel and warming up the engine.

On the other hand, when the start flag is reset one minute after the engine is started, the process proceeds to step 54, where the output signal of the rotation speed sensor 36 representing the engine rotation speed N, the output signal of the air flow meter 5 representing the intake air amount Q, And the output signal of the water temperature sensor 25 is read without indicating the cooling water temperature T. Next, in step 55, it is determined whether the engine speed N is greater than or equal to a certain value C, in step 56 it is determined whether Q/N is greater than or equal to a certain value C, and in step 57, the cooling water temperature T
It is determined whether or not is equal to or greater than a certain value C.

Note that here, Q/N corresponds to the engine load. N≦A,Q
If /N≦B and T<C, that is, when the engine is operating at low speed and low load before completion of warm-up, the process proceeds to step 53, and high-temperature air is supplied into the surge tank 11 in the same way as at the time of starting. In other operating states, that is, whether N>A or Q/N>
B or T>C, the process proceeds to step 58, where the electromagnetic switching valve 24 is turned off. At this time, the bypass passage 22 is connected to the intake duct 10 via the bypass passage 22a, and therefore, the air cooled by the intercooler 9 is supplied into the surge tank 11. Therefore, the occurrence of knocking is prevented. Note that in this embodiment as well, the partition wall 42 of the exhaust manifold 15 is still cooled by the air flowing in the air flow passage 44.

〔Effect of the invention〕

Since cooling air can be sent into the air flow passage of the partition wall of the exhaust manifold by utilizing the pressure difference before and after the throttle valve, there is an advantage that only piping is required to supply the cooling air.

[Brief explanation of the drawing]

Figure 1 is an overall view of the internal combustion engine, Figure 2 is an enlarged sectional view of the exhaust manifold and exhaust turbocharger in Figure 1, and Figure 3 is an enlarged sectional view of the exhaust manifold and exhaust turbocharger in Figure 1.
The figure is a sectional view taken along the line m-m in Fig. 2, Fig. 4 is a sectional view of another embodiment, Fig. 5 is an overall part of another embodiment of the internal combustion engine, and Fig. 6 is a switching valve. 7 is a flowchart for executing control. DESCRIPTION OF SYMBOLS 1... Engine body, 2... Exhaust turbocharger, 3... Compressor, 8.10... Intake duct, 9... Intercooler, 15... Exhaust manifold, 18... Throttle valve, 44...Air flow passage.

Claims (1)

[Claims] In an internal combustion engine in which an exhaust manifold has a pair of exhaust gas outlets separated from each other by a partition wall, an air flow passage is formed within the partition wall, and a bypass passage is branched from an intake passage leading from a compressor of an exhaust turbocharger to a throttle valve. An exhaust manifold cooling device in which the bypass passage is connected to the intake passage downstream of the throttle valve via the air flow passage.