JPH0526253Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a cooling device for an exhaust manifold.

[Conventional technology]

Japanese Utility Model Application No. 56-101445 discloses a cylinder head with a built-in exhaust manifold, in which a water jacket is formed in a side wall having an opening, and the opening is covered by a lid member. . Japanese Utility Model Application No. 58-127119 discloses a cooling water passage formed in an exhaust manifold by a sheet metal member. Japanese Utility Model Application Publication No. 57-112030 discloses an example in which a cooling water passage is provided in the central partition of an exhaust manifold connected to a twin-entry turbocharger.

[Problem that the invention attempts to solve]

As described in the above publications, overheating of exhaust system components can be prevented by forming a cooling water passage in the exhaust manifold. However, by providing the cooling water passage in the exhaust manifold, it is necessary to provide a cooling capacity larger than that of the conventional exhaust manifold, and the heat dissipation load on the radiator increases. Furthermore, if a cooling capacity is provided appropriately at high speeds and high loads, there is a problem in that the cooling is excessive at times such as light loads, resulting in a decrease in the temperature of the exhaust gas and a decrease in the effectiveness of the catalyst. for that,
If the cooling water is supplied depending on the engine operating state, the cooling water will suddenly flow into the high-temperature exhaust manifold, causing a problem that the exhaust manifold will receive a thermal shock.

[Means for solving problems]

According to the present invention, in an exhaust manifold cooling device having a partition wall for grouping exhaust systems within the exhaust manifold, a sub-cooling water passage is provided in the partition wall, and the entrance of the cooling water passage is connected to the main cooling water passage of the exhaust manifold. At the same time, a control valve is placed on the outlet side of the main cooling water passage, and cooling water is constantly passed through the sub-cooling water passage, and cooling water is passed through the main cooling water passage depending on the engine operating status. A cooling device for an exhaust manifold is provided.

〔Example〕

FIG. 4 shows an example in which the present invention is applied to an internal combustion engine equipped with a twin-entry turbocharger 10, which includes an exhaust turbine 14 connected to an exhaust manifold 12 extending from the engine body, and an intake manifold ( (not shown). The exhaust manifold 12 has branch pipes 18 communicating with each cylinder, and a collecting pipe 20 that collects these branch pipes 18. A partition wall 22 is provided that extends in the central part of the collecting pipe 20 in the axial direction and divides the branch pipes 18 into two groups.
Two exhaust passages 12a and 12b are formed. These groups are divided to prevent exhaust interference between cylinders in each exhaust passage 12a, 12b.

Corresponding to the two exhaust passages 12a and 12b of the collecting pipe 20 of the exhaust manifold 12, two exhaust passages 14a and 14b are also formed in the inlet pipe portion of the exhaust turbine 14 of the turbocharger 10, and these are spiral scroll passages. and opens toward the turbine wheel. The collecting pipe 20 of the exhaust manifold 12 and the inlet pipe portion of the turbocharger 10 are connected to each other by flanges.

Figures 1 to 3 show this exhaust manifold 12.
FIG. As shown in FIG. 3, the flange end faces of the collecting pipe 20 and the branch pipes 18 extend vertically parallel to each other. A main cooling water passage 26 is formed in the lower part of the collecting pipe 20 by a horizontal molded wall 24 that is molded integrally with the exhaust manifold 12 . This main cooling water passage 26
extends laterally across the branch to each branch pipe 18 of the exhaust manifold 12 and has a length substantially close to the lateral length of the exhaust manifold 12 . The main cooling water passage 26 has a cooling water inlet 28 and an outlet 30.

The central partition wall 22 described above extends vertically so as to separate the collecting pipe 20 and branch pipes into two exhaust passages 12a and 12b. Sub-cooling water passage 32
However, in this vertically extending central partition wall 22,
It is formed to vertically penetrate the central partition wall 22. The lower end of the sub-cooling water passage 32 opens into the main cooling water passage 26 to form an inlet 34 thereof. The upper end of the sub-cooling water passage 32 is formed as an outlet 38. As shown in FIGS. 1 to 3, the cross-sectional area of the main cooling water passage 26 is formed to be considerably larger than the passage cross-sectional area of the sub-cooling water passage 32.

Referring to Figure 1, the engine body (E/G) 40
Also shown is the cooling water circulation system of the exhaust manifold 12. In the cooling water circulation line 42 of the engine body (E/G) 40, a known water pump 44 is installed toward the upstream side of the engine body (E/G) 40.
A radiator 46 and a thermostat 48 are arranged. An inlet 28 of the main cooling water passage 26 of the exhaust manifold 12 is connected to a portion of the cooling water circulation line 42 on the outlet side of the engine body 40 by a supply line 50 . An outlet line 52 is connected to the outlet 30 of the main cooling water passage 26, and an outlet line 54 is connected to the outlet 38 of the sub-cooling water passage 32. These outlet lines 52 and 54 are joined by a merging line 56 and then connected to a portion of the cooling water circulation line 42 of the engine body 40 in front of the thermostat 48. Therefore, the main cooling water passage 26 and the sub-cooling water passage 32 of the exhaust manifold 12 are connected to the engine body 4.
After leaving the exhaust manifold 12, this cooling water is supplied to the engine body 40 again through the thermostat 48 and the radiator 46. An electric fan 58 is attached to the radiator 46.

Further, an electromagnetic control valve 60 is disposed in the middle of the outlet line 52 on the outlet side of the main cooling water passage 26 of the exhaust manifold 12, and the electromagnetic control valve 60 is opened and closed depending on the operating state of the engine. Therefore, when the electromagnetic control valve 60 is closed, a small amount of cooling water flows only through the sub-cooling water passage 32, and the electromagnetic control valve 6
0 is open, a large amount of cooling water is supplied through the main cooling water passage 26 and the sub cooling water passage 32. Further, a three-way solenoid valve 62 is disposed in the middle of the merging line 56, and a bypass line 64 is connected from the three-way solenoid valve 62 to between the radiator 46 and the water pump 44 of the cooling water circulation line 42.

The electric fan 58, the electromagnetic control valve 60, and the three-way electromagnetic valve 62 are controlled by a control device 70. The control device 70 is configured as a microcomputer, and includes a central processing unit (CPU) 72 having calculation and control functions, a read-only memory (ROM) 74 for storing programs, and a random access memory (RAM) for storing data. )76
These are interconnected by a bus 78 and have an input/output interface (I/O interface).
O means) 80 is also connected. Signals from various sensors that detect engine operating conditions are input to the control device 70. For example, in order to detect the engine load, a signal a from an air flow meter that detects the amount of intake air, an engine rotation speed signal b, an engine cooling water temperature signal c, etc. are used.

FIG. 5 is a diagram showing an example of a flowchart for controlling the electric fan 58, the electromagnetic control valve 60, and the three-way electromagnetic valve 62. First, in step 90,
It is determined whether the engine cooling water temperature Tw is higher than a predetermined value T. If no, proceed to steps 91 and 92, open the bypass path of the three-way solenoid valve 62, allow the cooling water that has passed through the exhaust manifold 12 to bypass the thermostat 48 and the radiator 46, and supply warm cooling water to the engine body 40. By doing so, warm-up performance is improved, and the electric fan 58 is stopped to stop excessive cooling of the radiator 46. Further, the process proceeds to step 93, where the electromagnetic control valve 60 is closed so that the cooling water flows only through the sub-cooling water passage 32 of the exhaust manifold 12, which has a small passage area. Since the amount of cooling water flowing only through the sub-cooling water passage 32 is small, the effect of cooling the exhaust manifold 12 is small, so that the temperature of the exhaust manifold 12 is increased in a short time, and warm-up is performed quickly.

If YES in step 90, warm-up has been achieved, so proceed to steps 94 and 95, close the bypass path of the three-way solenoid valve 62, and switch the cooling water to thermostat 4.
8 and radiator 46 to radiate heat from the cooling water and drive an electric fan 58 to increase the cooling capacity. Note that the electric fan 58 does not need to be driven at the same time as the three-way solenoid valve 62 is closed, and can be driven depending on the operating conditions that require cooling capacity.

Next, the process proceeds to step 96, where it is determined whether the intake air amount (Q/N) detected by the air flow meter is greater than a predetermined value A. When the intake air amount (Q/N) is larger than the predetermined value A, it is determined that the load is high and the process proceeds to step 97. step 97
Then, the detected engine speed (NE) is set to the predetermined value B.
Determine whether it is greater than. When the engine speed (NE) is greater than the predetermined value B, the process proceeds to step 98, and the electromagnetic control valve 60 is opened. When the solenoid control valve 60 is opened, the exhaust manifold 1
A large amount of cooling water begins to flow through the second main cooling water passage 26, and at the same time, cooling water continues to flow through the sub cooling water passage 32 as well. In this manner, in operating conditions where the exhaust gas temperature rises sharply, a large amount of cooling water is allowed to flow to effectively cool the exhaust manifold 12.
By the way, if the cooling capacity is suddenly increased in this way, the exhaust manifold 12 will receive a severe thermal shock, but in the present invention, a small amount of cooling water is constantly flowing through the sub-cooling water passage 32 even before that, so that at least the cooling water is Since gradual cooling is always performed in the area in contact with the exhaust manifold 12, even if a large amount of cooling water is suddenly supplied, there is no sudden change in heat, and the durability of the exhaust manifold 12 can be ensured. .

If the answer at steps 96 and 97 is NO, the process proceeds to step 93 and the electromagnetic control valve 60 is closed. Then, the cooling water is supplied only to the sub-cooling water passage 32. Supplying cooling water to the sub-cooling water passage 32 after warm-up in this manner is not only effective as a link between the intermittent supply of cooling water passing through the main cooling water passage 26 as described above, but also relatively effective. This is effective in alleviating the local heat load even during low load conditions where the rise in exhaust gas temperature is small. In an engine equipped with a twin-entry turbocharger, the central partition wall 22 is sandwiched between two exhaust passages 12a and 12b.
is subject to particularly severe heat loads. In the present invention, a sub-cooling water passage 32 is provided that penetrates the central partition wall 22, and even when the electromagnetic control valve 60 is closed during low load, a sufficient amount of cooling water flows through the sub-cooling water passage 32. Watered. Therefore, the partition wall, which is subject to a large heat load even under low load conditions, is constantly cooled regardless of the amount of cooling water flowing through the main cooling water passage.

Steps 96 and 98 in FIG. 5 are for setting the opening conditions for the electromagnetic control valve 60 in a region where the operating state of the engine is high load and high rotation speed. Such a region can be defined as desired. FIG. 6 shows an example of the opening/closing area of the electromagnetic control valve 60 determined for the engine load and rotation speed, and the area above the solid line is the opening area of the electromagnetic control valve 60. In this case, even if the load is low, the electromagnetic control valve 60 is opened if the rotation speed is high, and similarly, even if the rotation speed is relatively low, the electromagnetic control valve 60 is opened if the load is high.

[Effect of idea]

As explained above, according to the present invention, by constantly supplying cooling water to the sub-cooling water passage and supplying cooling water to the main cooling water passage according to the engine operating condition, a large heat load can be avoided even during low load. In addition to sufficiently cooling the partition wall of the exhaust manifold that receives the heat, the exhaust manifold can be appropriately cooled depending on the operating state of the engine, and the durability of the exhaust manifold can be improved.

[Brief explanation of drawings]

Fig. 1 is a front view of the exhaust manifold according to the present invention as seen from the flange of the collecting pipe, Fig. 2 is a sectional view of the exhaust manifold taken along the line - of Fig. 3, and Fig. 3 is a view of the exhaust manifold of Fig. 1. FIG. 4 is a cross-sectional view taken along the line -, and FIG. 4 is a diagram showing an example in which the exhaust manifold according to the present invention is connected to a turbocharger.
FIG. 5 is a flow chart of the control of the electromagnetic control valve etc. in FIG. 1, and FIG. 6 is a diagram showing the opening/closing area of the electromagnetic control valve. 12... Exhaust manifold, 18... Branch pipe, 2
0... Collection pipe, 22... Central bulkhead, 26... Main cooling water passage, 32... Sub-cooling water passage, 60... Solenoid control valve.

Claims (1)

[Scope of utility model registration request] In a cooling device for an exhaust manifold having a partition wall for grouping exhaust systems within the exhaust manifold, a sub-cooling water passage is provided in the partition wall, an inlet of the cooling water passage is connected to a main cooling water passage of the exhaust manifold, and a main cooling water passage is connected to the main cooling water passage of the exhaust manifold. A control valve is placed on the outlet side of the water passage, and cooling water is constantly passed through the sub-cooling water passage.
A cooling device for an exhaust manifold, characterized in that cooling water is passed through the main cooling water passage according to engine operating conditions.