JPH023015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a torque characteristic improving device for a supercharged multi-cylinder internal combustion engine.

[Conventional technology and its issues]

As is well known, the majority of superchargers used in four-stroke diesel engines are exhaust turbo superchargers, and in the low engine speed range, the supply air pressure, or air volume, is extremely low. If you try to maintain the fuel injection amount at medium and high speeds even in such a low rotation range, the exhaust smoke will turn into black smoke, so you will have to drastically reduce the amount of fuel, resulting in a lack of torque. . Therefore, various proposals have been made to address this torque deficiency in supercharged diesel engines for vehicles. For example, they have proposed a device that reduces the opening area of the exhaust turbine nozzle to obtain sufficiently high supply air pressure even at low speeds.

On the other hand, general-purpose small diesel engines (200PS or less)
Although supercharging is progressing, there is a need to improve the lack of torque and deterioration of exhaust concentration due to supercharging even in engines installed in agricultural or construction machinery that are often used at medium to low speeds and high loads. has been done.

By the way, as a countermeasure for the lack of torque in the low speed rotation range of a diesel engine with a supercharger, proposals have been made such as matching an exhaust turbo supercharger with emphasis on low speeds and combining intake inertia supercharging. The proposal for combined use of supercharging is attracting attention as a simple countermeasure that does not require modification of the exhaust turbocharger itself. However, even with such a proposal, the optimal conditions for intake inertia supercharging are determined by the engine speed. For example, if the intake pipe length is set in a low speed range, the intake inertia effect will not be synchronized in the high speed range and the volume will increase. Efficiency decreases, and it even becomes lower than the supply pressure of only the exhaust turbo supercharger, resulting in poor volumetric efficiency.

Therefore, in order to eliminate this inconvenience,
In Publication No. 57-153730, in order to avoid intake interference, air column vibration passages are formed in two groups in the intake inertia pipe that communicates the intake manifold with the compressor of the supercharger, and the air column vibrations of these two groups are A proposal is to communicate with each other in the middle of the passage, and in the low-speed rotation range, this communication is closed to perform intake inertia supercharging, and in the high-speed rotation range, this communication is opened to suppress the pressure amplitude in the intake inertia pipe. is being done.

However, in the case of such a proposal, the inertia effect increases as the intake inertia pipe becomes longer and its diameter becomes smaller. Therefore, in the high speed rotation range where the inertia effect is not required, the flow resistance of the intake inertia pipe will have a large effect. , deteriorating engine performance.

In addition, in Japanese Utility Model Application Publication No. 56-105626, in an intake inertia pipe that communicates the intake manifold with the compressor outlet of the supercharger, a damping chamber is interposed on the compressor outlet side, and a plurality of intake inertia pipes are connected to the damping chamber. and a plurality of short-circuit pipes are connected to an intake manifold, and a switching valve is provided at the downstream end junction of these intake inertia pipes and the short-circuit pipes. ing.

However, in such a proposal, in order to suppress the pressure amplitude in at least two or more short-circuited pipes when transitioning from a low-speed rotation range to a high-speed rotation range, there is a need for a plurality of intake inertia pipes and a plurality of short-circuited pipes. A damping chamber that is provided with a switching valve and damps intake vibrations generated by operating the plurality of switching valves needs to have a large capacity. Furthermore, two or more short-circuit tubes are required.

Furthermore, in Japanese Patent Publication No. 58-38613, in the intake inertia pipe that communicates the intake manifold with the compressor outlet of the supercharger, a damping chamber is interposed on the compressor outlet side, and the damping chamber surrounds the intake manifold. A torque characteristic improvement device for a supercharged internal combustion engine has also been proposed in which air is directly supplied to the intake manifold (short-circuit) from this damping chamber via a switching valve in a high-speed rotation range.

However, in this proposal, since the damping chamber surrounds the intake manifold, the damping chamber needs to have a large capacity.

[Means to solve the problem]

Therefore, the present invention was created in order to eliminate the disadvantages of the prior art, and its gist is to connect the intake manifold of a multi-cylinder internal combustion engine and the compressor outlet of the exhaust turbo supercharger for the engine. In an internal combustion engine with an exhaust turbo supercharger that communicates with each other through an intake inertia pipe through a damping chamber provided on the compressor outlet side, the intake inertia pipe and the intake manifold are divided into two groups, and the two groups are connected to each other. The intake inertia pipes are communicated with each of these two groups of intake manifolds, and the two groups of intake inertia pipes are enabled to communicate with each other on the downstream side thereof,
A single short-circuit pipe with low flow resistance that communicates with the damping chamber is placed at this communication point, and the pipe is opened and closed by the supply air pressure of the damping chamber.
A single 3-way communication valve is provided, and the 3-way communication valve is opened in the engine high speed range, and the intake air from the short-circuit pipe is
Through these two groups of intake inertia tubes, these two
This is a multi-cylinder internal combustion engine with an exhaust turbo supercharger that supplies air to each group's intake manifolds.

[First Embodiment] Next, the configuration of the present invention will be described in detail with reference to first and second embodiments shown in the accompanying drawings.

FIG. 1 is a conceptual plan view of the first embodiment of the present invention;
FIG. 2 is a cross-sectional view of a main part, and FIG. 3 is a cross-sectional view taken from A to A in FIG. 2.

In FIG. 1, reference numeral 1 denotes a cylinder head, and this engine is a four-cylinder vertical diesel engine, and is mounted on, for example, an agricultural tractor or a small construction machine. 2 is a radiator, which is suction-cooled by a fan 3. 4 is the floor in the exhaust turbo supercharger, 5
indicates a turbine, and 6 indicates an exhaust manifold. These structures are commonly known from exhaust turbocharged diesel engines.

Here, in this embodiment, a damping chamber 7 is provided at the outlet of the blower 4, and two groups of intake inertia pipes 8 and 9 are vertically faced on one side of the damping chamber 7, and the upper intake inertia pipe 8 is connected to the engine. The lower intake inertia pipe 9 is for the 1st and 4th cylinders of the engine. A short-circuit pipe 11 with low flow resistance faces the other side of the damping chamber 7, and these intake inertia pipes 8, 9 and short-circuit pipe 11 connect to the three-way communication valve 1.
It is merged at 2.

That is, in FIGS. 2 and 3, the upper and lower intake inertia pipes 8 and 9 are at the same equivalent pipe length position, respectively.
are connected and communicated, and at this connection point, the three-way communication valve 12
The piston valve body 13 communicates with the piston valve body 13. This piston valve body 13 has a conical head portion 14 to reduce flow resistance, and a spring 15 is inserted inside the piston valve body 13, and the elasticity of the spring 15 constantly presses the head portion 14 against the seat portion 16 to close it. There is. The body of the piston valve body 13 opens and closes communication between the upper and lower intake inertia pipes 8 and 9. Air supply pressure from the damping chamber 7 acts on the head portion 14 at all times.

Note that 18 is an adjuster bolt that adjusts the elasticity of the spring 15. Further, reference numeral 19 denotes a fine hole, and the fine hole 19 makes the inside of the piston valve body 13 atmospheric pressure.

To describe the operation of the first embodiment, if the engine of this embodiment is mounted on an agricultural tractor that requires a large tractive force at low speeds, the engine can be operated under a high load in a low speed rotation range. Therefore, the discharge pressure of the blower 4 is low in the low speed rotation range, and therefore, the supply air pressure introduced into the three-way communication valve 12 from the short-circuit pipe 11 is smaller than the elasticity of the spring 15.
The piston valve body 13 is pressed against the seat portion 16 and is closed. Therefore, the upper and lower intake inertia pipes 8 and 9 do not communicate with each other, and the air supplied from the blower 4 is supplied from these intake inertia pipes 8 and 9 to the intake manifold with intake inertia supercharging. Ru. Next, when the engine shifts to a high-speed rotation range, the discharge pressure from the blower 4 increases, and the discharge pressure from the short-circuit pipe 11 increases.
The supply air pressure introduced into the side communication valve 12 is greater than the elasticity of the spring 15, causing the piston valve body 13 to move backward and causing the upper and lower intake inertia pipes 8 and 9 to communicate with each other. Since the air is also introduced from the intake inertia pipes 8 and 9, the inertia supercharging by the intake inertia pipes 8 and 9 is suppressed at once. Therefore, in the high-speed rotation range, the supply air does not pass through only the narrow intake inertia pipes 8 and 9, so there is no pressure drop due to pipe friction or a drop in volumetric efficiency due to pressure amplitudes in the intake pipes that are not synchronized at high speeds.

[Second Embodiment] FIG. 4 is a plan view of the main part of the second embodiment of the present invention,
FIG. 5 is a further sectional view of the main part of FIG.
Components common to those in the embodiment are given the same reference numerals.

The main difference between the device of this embodiment and the device shown in the first figure is that the damping chamber is replaced with a short-circuit pipe joint 1', and this short-circuit pipe joint 11' and the upper and lower intake inertia pipes 8, 9 are connected to each other. The branching point is made of an elastic material, such as rubber, to further reduce the volume of the damping chamber. And short-circuit pipe joint 1
1', the upper and lower intake inertia tubes 8, 9
are orthogonal and branch, and short-circuit pipe joint 1
The inner diameter D of 1' is made equal to or larger than the inner diameter d of the intake inertia pipes 8 and 9. Therefore,
It has little effect on intake inertia.

Note that if the movement of the piston valve body 13 in the first and second embodiments is controlled in conjunction with an electronically controlled injection system (not shown), the volumetric efficiency will be matched to the optimum injection amount, and a more desirable air supply amount will be achieved. can get. For example, as shown in FIG. 7, the opening degree of the three-way communication valve 12 in the first embodiment, that is,
The relationship between the retraction length l of the piston valve body 13 (see Fig. 3), the fuel consumption rate f, and the exhaust gas concentration Sd (boss smoke meter index) is shown. The optimum injection amount of the fuel injection pump may be controlled in conjunction with the optimum injection amount.

〔Effect of the invention〕

According to the present invention, the following effects can be expected.

In the low engine speed range, the intake inertia pipe compensates for the lack of supercharging from the exhaust turbo supercharger, and in the high speed range, the short-circuit pipe from the supercharger provides a large amount of supercharging, so the flow resistance in the intake inertia pipe is reduced. Of course, it is possible to avoid this problem, but the intake inertia pipes are divided into two groups at a point where they can communicate with each other on the downstream side.
A 3-way communication valve is provided, and when the rotation speed changes from a low speed range to a high speed range, the 3-way communication valve is opened to connect these two groups of intake inertia pipes with each other, and a large amount of intake air is released from the short-circuit pipe. With the introduction of In addition to minimizing (in some cases, making it unnecessary) the damping time can be extremely shortened.

A short-circuit pipe is provided at the communication point of the intake inertia pipes divided into two groups, and a three-way communication valve is provided at the intersection of these three passages, so the structure is simple since only one valve is required, and multiple There is no intake vibration caused by the opening and closing of the valve, and since there is only one valve, control such as vibration damping can be performed reliably.

Since only one 3-way communication valve is required, in other words, only one short-circuit pipe is required, and the structure is simple.
The pressure amplitude generated in the short-circuit pipe can be easily suppressed, and the damping chamber can be minimized accordingly.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view of a first embodiment of the present invention;
2 is a sectional view of the main part of FIG. 1, FIG. 3 is a sectional view taken from A to A in FIG. 2, FIG. 4 is a plan view of the main part of the second embodiment of the present invention, and FIG. Cross-sectional view of main parts in Figure 4, No. 6
The figure is a comparison diagram, and FIG. 7 is a graph showing the relationship between the three-way communication valve and fuel consumption rate. 4... Blower, 7... Damping chamber, 8, 9... Intake inertia pipe, 11... Short circuit pipe, 12... 3-way communication valve.

Claims (1)

[Scope of Claims] 1. An exhaust system in which an intake manifold of a multi-cylinder internal combustion engine and a compressor outlet of an exhaust turbo supercharger for the engine are communicated via an intake inertia pipe via a damping chamber provided on the compressor outlet side. In the internal combustion engine with a turbo supercharger, the intake inertia pipes and the intake manifolds are each divided into two groups, the intake inertia pipes of these two groups are communicated with the intake manifolds of these two groups, and the intake inertia pipes of these two groups are connected to the intake manifolds of these two groups. The inertial tubes are made to be able to communicate with each other on the downstream side thereof, and one short-circuit tube with low flow resistance that communicates with the damping chamber is faced at this communication point, and the inertia tubes are opened and closed by the air supply pressure of the damping chamber. A single 3-way communication valve is provided, and the 3-way communication valve is opened in the engine high speed range, so that the intake air from the short-circuit pipe is transferred to the intake air from these two groups through the intake inertia pipes of these two groups. A multi-cylinder internal combustion engine with an exhaust turbo supercharger that supplies each manifold.