JPH03260368A - Intake device of engine - Google Patents

Abstract

PURPOSE:To prevent deformation due to heat and vibration by connecting a pair of surge tanks, arranged above right and left banks arranged in V shape, to each other through a passage pipe and by bending said pipe approximately in its center so as to prevent it from forming a brace against the surge tank. CONSTITUTION:In a V-engine 1, a pair of surge tanks 5, 6 are provided above left and right banks 2, 3, and branch pipes 7, 8, which constitute independent intake passages to respective cylinders are extended from respective surge tanks 5, 6. Communication pipes 9, 10 for constituting communication paths with an intercooler 12 are extended forward on the end parts of the engine front sides of respective surge tank 5, 6. Here a curve-shaped intercooler bypass passage pipe 24, branched in a fork shape, is provided, and respective end parts of these branch pipes are connected to the point end sides of respective communication pipes 9, 10 through connection parts 9a, 10a. The curved part of this passage pipe 24 is connected to an air bypass pipe 23 additionally provided in a supercharger 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for a V-type engine in which surge tanks are provided above left and right banks, respectively.

(Prior art) In an engine, a mechanical supercharger is provided downstream of the throttle body in the intake passage, and the discharge port side of the mechanical supercharger is connected to a surge tank via an intercooler. This has been conventionally known as described in Japanese Patent No. 63-51121. In an engine equipped with such a mechanical supercharger and intercooler, as described in the above publication, an air bypass passage is formed by bypassing the supercharger and intercooler, and air is supplied to this air bypass passage. By installing a bypass valve, the air bypass valve is opened in the non-supercharging area on the low load side to bypass the supercharger and perform natural intake, and when the load becomes high, the air bypass valve is closed to perform supercharging. is normal. It has also been proposed to supply air by bypassing the intercooler, especially at low loads, to raise the intake air temperature and improve combustion, thereby improving fuel efficiency and emitter temperature.

By the way, in a vehicle equipped with a supercharged engine,
In order to keep the engine room small, it is necessary to arrange the intake system, including the supercharger, as compactly as possible to increase the ease with which the engine can be mounted.

Therefore, particularly in the case of a ■-type engine, it has been conventional practice to utilize the space between the left and right banks forming a V-shape and to dispose a supercharger in this space. In that case, one surge tank is provided above the left and right banks, and the intercooler is placed in front of the supercharger in a direction perpendicular to the crankshaft, making it possible to create a compact layout for the entire intake system.

In addition, when providing a passage to supply air by bypassing the intercooler as described above, one end of the passage pipe for this purpose communicates with the downstream position of the air bypass valve between the left and right banks, and the other end connects to the downstream position of the air bypass valve. Normally, it is arranged so that it branches into two and communicates with the left and right surge tank sides.

(Problems to be Solved by the Invention) When a surge tank is provided above each bank of the left and right banks of a V-type engine, and an intercooler bypass passage pipe is provided between the left and right banks so as to communicate with each of the surge tanks, This intercooler bypass passage pipe stretches both surge tanks from the inside, and as a result, large stress is generated when the left and right banks are subjected to thermal deformation or vibration, leading to problems such as damage to the passage pipes in areas with weak rigidity. arise.

The present invention has been made to solve the above-mentioned problems, and has a stress relieving function in the passage pipes that constitute the communication passage between the surge tanks, which are provided independently above the left and right banks. The purpose is to prevent damage to passage pipes, etc. due to thermal deformation and vibration.

(Means for Solving the Problems) An engine intake system according to the present invention is an engine in which surge tanks are provided above left and right banks arranged in a V-shape, and a passage that connects both surge tanks to each other is provided in the engine. It is characterized by being bent approximately at the center, thereby achieving the above object.

In an engine with an intercooler installed in a direction perpendicular to the crankshaft, a passage that communicates both surge tanks with each other is extended from the upstream portion of the communication passage between the intercooler and each surge tank to the opposite side of the intercooler. , by communicating with the upstream of the turbocharger at its central bend,
This passage can function as an intercooler bypass passage and also function as a resonance passage at the same time.

(Function) The passage that connects the surge tanks above the left and right banks with each other between the left and right banks arranged in a V-shape is bent at approximately the center, so that the passage acts as a support for the surge tank. It deforms itself, thereby absorbing and relieving stress caused by thermal deformation and vibration of the left and right banks.

Furthermore, passages that communicate the two surge tanks with each other extend from the upstream portions of the respective communication passages between the intercooler and the left and right surge tanks to the side opposite to the intercooler, and the central bent portion thereof communicates with the upstream side of the supercharger. As a result, this passage functions as an intercooler bypass passage that bypasses the supercharger and intercooler during low loads. This allows high-temperature natural intake at low loads. Also,
In this case, the passage connecting the two surge tanks will necessarily be long, and a tuning point for the resonance effect will be obtained in the low rotational speed range of the engine. Therefore, torque at low speeds is improved.

(Example) Examples will be described below based on the drawings.

FIG. 1 is a plan view of a V-type engine according to an embodiment of the present invention, FIG. 2 is a rear view thereof, and FIG. 3 is a side view thereof. In this embodiment, the engine 1 is a V-type six-cylinder engine, and when viewed from the front, the three cylinders in the left bank 2 and the right bank 3 are such that each cylinder in the left bank 2 is connected to each cylinder in the right bank 3. In contrast, they are arranged so as to be offset by a predetermined amount from each other in the crankshaft direction. A Lysholm type supercharger 4 is disposed in the space between the left and right banks 2 and 3 in the direction of the crankshaft.

Surge tanks 5.6 are provided above the left and right banks 2.3, each extending in the crankshaft direction.

And each surge tank 5.6 has left and right banks 2.3
Branch pipes 7 and 8 forming independent intake passages to each cylinder between the cylinders.
A communication pipe 9. is provided at the end on the front side of the engine to form a communication path with an intercooler, which will be described later. The lO is extended forward. In addition, branch pipes 7 and 8 of each cylinder
An injector mounting hole 11a is provided in each of the injector mounting holes 11a, and an injector 11 for fuel injection is disposed therein.

An intercooler I2 is disposed in front of the engine 1 in a direction perpendicular to the crankshaft. intercooler 12
There are two cooling parts 13.1 corresponding to the left and right banks 2.3.
4, which are arranged substantially symmetrically with respect to the engine center.

And a common inlet pipe 15 is provided at the center position,
Outlet pipes 16 and 17 are provided at both left and right ends. The inlet pipe 15 is connected to a discharge pipe 18 provided from the top of the supercharger 4 toward the front.

The supercharger 4 has an inlet portion 19 at the rear end in the longitudinal direction, and a throttle body 20 is connected to the inlet portion 19.

In the inlet portion 19, the side connecting the throttle body 20 is offset toward the left bank 2 with respect to the engine center, and the connecting surface is inclined toward the right bank 3. The throttle body 20 as a whole is offset toward the left bank 2, and its link mechanism 21 is disposed horizontally toward the offset space behind the left bank 2.

Further, an air bypass valve 22 is connected to the inlet portion 19, and a portion directly downstream of the throttle body 20 is communicated with the discharge f18 of the supercharger 4 via the air bypass valve 22 and a bypass passage pipe 23 connected to the air bypass valve 22. has been done.

Furthermore, an intercooler bypass passage pipe 24 is connected to the connection part of the air bypass valve 22 with the bypass passage pipe 23, and an intercooler bypass valve 25 is provided downstream of the connection part.

The intercooler bypass passage pipe 24 is connected from above to a downstream position of the air bypass valve 22, and is bent into a dogleg shape and branches into two parts, including the left and right surge tanks 5,
The ink-cooler side communication pipe 9.10 is integrally formed with the ink-cooler side communication pipe 9.10.

The tip of each of the above-mentioned communicating tubes 9. It is connected from above to connecting portions 9a and 102L that branch and rise from below the tip of the IO. In FIG. 1, 26 indicates the position of the EGR inlet, and 27 indicates the position of the PCV inlet. EGR introduction port 2
6 and PCV inlet 27 are EGR gas or PCV inlet 27.
It is necessary to provide the V gas upstream of the surge tanks 5 and 6 so that the V gas is well mixed with air and introduced into the engine.

The outlet pipes 16, 17 at both ends of the intercooler 12 are rigidly bolted to the communication pipes 9, 10 of the left and right surge tanks 5, 6 through joints 28 made of thick rubber, respectively, so that these surge tanks 5, 6, 6 and a bracket (not shown) separately fixed below. A duct 31 that extends beyond the radiator 29 located at the front and opens at the vehicle grille 30 is provided to cover the front surface of the intercooler 12, and a membrane-like rubber seal is bolted to the inner surface of the rear end of the duct 31. 32 seals between +s between the duct 31 and the intercooler 12.

The air bypass valve 22 is constituted by a diaphragm-type pressure-responsive valve, and opens when the engine is under low load.
It gradually closes when the boost pressure exceeds a predetermined value, and becomes fully closed when the load is high. Further, the intercooler bypass valve 25 is also constituted by a diaphragm type pressure-responsive valve, and opens when the load is low. and,
It begins to close from the lower load side than the air bypass valve 22, and fully opens when it enters the supercharging region. As a result, in the non-supercharged region, air is taken by bypassing the supercharger 4, and an increase in pressure loss is prevented. In addition, especially in the low load range,
Intake is performed while also bypassing the intercooler 12.

Therefore, during low load, the supercharger 4 is stopped and driving loss is reduced, and the air bypass reduces pressure loss.Furthermore, the intake air temperature increases, atomization is improved, and the combustion state is improved. This improves fuel efficiency and emissions (HC). On the other hand, when the load is high, the intercooler bypass valve 25 is fully closed, and sufficiently cooled air is supplied to the engine.
Abnormal combustion is prevented and reliability of the supercharger is ensured.

Further, the intercooler bypass passage pipe 24 is connected to the communication pipe 9.10 of the surge tank 5.6 on the upstream side of the EGR inlet 26 and the PCV inlet 27. Therefore, EGR gas and PCV gas do not return to the supercharger 4 side via the intercooler bypass passage pipe 24.

(Effects of the Invention) Since the present invention is configured as described above, with respect to the surge tanks provided independently above the left and right banks, the passage pipes constituting the communication passage between these surge tanks are not tensioned. Instead, it can deform itself due to thermal deformation or vibration. Therefore, stress can be alleviated and damage to the passage pipe and the like can be prevented.

[Brief explanation of drawings]

FIG. 1 is a plan view of a ■-type engine according to an embodiment of the present invention, FIG. 2 is a rear view thereof, and FIG. 3 is a side view thereof. l・Engine, 2: Left bank, 3: Right bank, 4: Supercharger, 5, 6: Surge tank, 9.10: Communication pipe, 12:
Intercooler, 24/Intercooler bypass passage pipe.

Claims (2)

[Claims] (1) An intake system for an engine in which a surge tank is provided above each bank of left and right banks arranged in a V-shape, in which a passage connecting both surge tanks to each other is bent approximately at the center thereof. (2) An intercooler is provided in a direction perpendicular to the crankshaft, and a passage that communicates both surge tanks with each other is extended from the upstream portion of the communication passage between the intercooler and each surge tank to the opposite side to the intercooler. 2. The engine air intake system according to claim 1, wherein the central bent portion thereof is connected to the upstream side of the supercharger.