JPH0561446B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention aims to re-burn the blow-by gas leaking inside the engine without releasing it into the atmosphere.
The present invention also relates to improvements in a blow-by gas recirculation device for maintaining the crank chamber at a state close to atmospheric pressure.

As exhaust gas regulations for vehicles become more stringent, devices such as those shown in FIGS. 1 and 2 have been proposed as means for treating unburned gas in engines.

The one in Figure 1 is the crank chamber Ec of engine E.
In order to recirculate the blow-by gas leaking into the intake pipe K, a part of the air taken in from the air cleaner Ac is used.The recirculation device B is separated from the engine E, and the first It is connected to the head cover C of the engine E by a pipe _P1 , and connected to the intake pipe K by a second pipe _P2 , and to a part of the air cleaner Ac by a third pipe _P3 . _The inside of the chamber is divided into upper and lower chambers _B1 and _B2 by _an annular partition plate _B3 , as shown in FIG. A valve body _B4 is disposed to close the opening of the partition plate _B3 , which is normally biased upward by a spring S from below.

Therefore, due to the operation of engine E, the crank chamber
The blow-by gas leaked during Ec enters the head cover C through the gap in the intake operating part in the cylinder head due to the intake action, and flows into the intake pipe K via the pipe _P1 , the reflux device B, and the second pipe _P2 . However, when the engine E is rotating at low speed, the negative pressure in the intake pipe K is small, so the valve body _B4 of the recirculation device B does not open. First, the blow-by gas flows into the intake pipe K through the through hole _B5 of the valve body _B4 , and when the rotation is at high speed, the valve body _B4 opens due to the large negative pressure in the intake pipe K, and the blow-by gas flows through the partition. It begins to flow through the openings in plate B ₃ .

By the way, a vehicle engine (for example, a diesel engine with a cylinder volume of 2200 c.c. and an output of 80 PH)
In this case, the negative pressure in the intake pipe changes significantly depending on the engine speed. The amount of blow-by gas leaking into the inside of the engine does not change like the negative pressure in the intake pipe.1000r.pm...approximately 30/min 2000rpm...3000rpm...35/min 4000rpm...40rpm It stays within an almost constant range Therefore, during high-speed rotation, the blow-by gas cannot follow the suction amount.
Part of the outside air taken in from the air cleaner Ac via the third pipe _P3 is replenished.

However, since the recirculation device B is of a separate type, setting it up requires piping inside the restricted engine room, making it difficult to work, and the capacity of the air cleaner AC is insufficient.
When it is clogged, a large negative pressure is generated in the crank chamber Ec, which may cause engine malfunction.

On the other hand, the one in Figure 2 has the recirculation device B' mounted directly on the engine head cover C to reduce piping and avoid using outside air to recirculate the blow-by gas _. Consisting of cap B ₁₂ ′ and body
B ₁₁ ′ has an inlet passage B ₁₃ ′ communicating with the head cover C and an outlet passage B ₁₄ ′ connected to the intake pipe.
A diaphragm f′ of the required diameter is sandwiched between B ₁₁ ′ and the cap B ₁₂ ′, and a spring S′ disposed in the cap B ₁₂ ′ normally closes the upper opening of the outlet passage B ₁₄ ′. When the engine is running, the blow-by gas leaking into the crank chamber, i.e. the pressure inside the engine, pushes up the diaphragm f' against the spring force of the spring S', opening the inlet passage B. ₁₃ ' and outlet passage _B14 ' are opened to allow blow-by gas to return to the intake pipe side.

By the way, as mentioned above, this device opens the gas passage by pushing up the diaphragm f' against the spring force of the spring S', that is, spring force (P) = gas pressure (F)
Since it takes the form of x diaphragm area (A),
The following problems are inherent.

In other words, the diameter of diaphragm f′ is 40 mm (area
12.5cm ² ) and try to open the diaphragm f' with the engine internal pressure at about 1 atm + 50 mmAq, which is close to atmospheric pressure, the spring force of the spring S' is 5×
Since 12.5≒60, we had to select a spring with a strength of about 60g, and in this way, we had to select a spring with a strength of about 60g.
It is difficult to handle and is not suitable for engines with severe vibration, so it is necessary to equalize the engine internal pressure.
If the spring force of the spring is 250 g, the effective diameter of the diaphragm will nearly double to approximately 80 mm, making the recirculation device itself larger. Conversely, if the effective diameter of diaphragm f' remains 40 mm and the spring force of spring S' is doubled to 120 g, the opposing internal pressure of the engine will be as high as 100 mmAq, which will interfere with engine operation. It turns out.

As described above, the conventional separation type that uses outside air and the diaphragm push-up type each have drawbacks in terms of performance and design.This invention was devised to improve these drawbacks, and the design It is a suction type without using troublesome springs, and does not use outside air.
As mentioned above, in a diesel engine for a vehicle, the intake pipe negative pressure changes greatly depending on the engine rotation speed, but we focused on the fact that the blow-by gas leaking into the engine does not change as much. During high-speed rotation, the gas flow path is narrowed to prevent excessive flow, and during low-speed rotation with low negative pressure, the gas flow path is widened to allow a constant amount of gas to flow smoothly, maintaining near atmospheric pressure inside the engine. It consists of a body and a cap that fits over the upper end of the body, and the body has a vertical inlet passage leading into the engine, and the inlet passage is connected to the intake pipe through a partition. The partition wall is provided with a small diameter orifice that communicates with the inlet and outlet passages, and between the body and the cap, a diaphragm is connected to the upper end opening of the outlet passage by the tension of the diaphragm itself. The lower end surface of the body is attached to the head cover of the engine so that the inlet passage communicates with the through hole of the head cover of the engine.

Referring to FIGS. 3 and 4, an embodiment of the present invention will be described. Reference numeral 1 denotes a circular planar body of a recirculation device A, which is attached onto a head cover C of the engine via a lower overhanging flange 1a. Inside the body 1, there is a vertical inlet passage 3 that aligns with the through hole Ca of the head cover C, and an L-shaped outlet passage 4 (approximately 12 mm to 15 mm in diameter) across the partition wall 1b. A pipe 4a is attached to the outlet end and connected to the intake pipe, and an orifice 5 with a small diameter (approximately 2 mm to 3 mm) is bored in the partition wall 1b and communicates with both passages 3 and 4. is,
A diaphragm 6 of a required diameter is sandwiched between the body 1 and a cap 2 covered on the body 1 at its peripheral edge, and the central portion is opened at the upper end of the outlet passage 4 by the tension of the diaphragm 6 itself. It is supported horizontally with a slight distance between the two.

Based on the above configuration, when the engine is operated and its rotational speed reaches a high speed of 3000r.pm to 4000r.pm, the negative pressure in the intake pipe becomes large, which causes the outlet passage of the recirculation device A to increase. 4, the diaphragm 6 is strongly attracted and closes the inlet end of the outlet passage 4.
The blow-by gas that enters the reflux device A from the through hole Ca passes exclusively through the narrow orifice 5 formed in the central partition wall 1b, and its flow rate is throttled by the orifice 5 while passing through the outlet passage 4. After that, it flows into the intake pipe. Therefore, excessive flow of gas is prevented, and a large negative pressure does not develop inside the engine.

On the other hand, during low-speed rotation with small negative pressure in the intake pipe, the suction force against the diaphragm 6 becomes small;
Since the internal pressure (positive pressure) of the engine does not change that much, the blow-by gas that enters the inlet passage 3 pushes up the diaphragm 6, and the outlet passage 4
The upper open end of the blow-by gas is opened, and most of the blow-by gas enters the outlet passage 4 through the open end, and a portion passes through the orifice 5, enters the outlet passage 4, and flows toward the intake pipe.

In this manner, during low-speed rotation with low intake pipe negative pressure, the gas flow path widens, allowing blow-by gas with a substantially constant leakage amount to flow without delay, and no abnormal positive pressure is created inside the engine. In this case, the degree of opening of the diaphragm 6 changes depending on the engine speed in the low speed range.

Note that the shapes of the body 1 and the cap 2 are not limited to the circular shape as shown in the drawings, but may be other shapes such as a square shape or a star shape.

As described above, in the present invention, as a recirculation device for blow-by gas in an engine, the body has a vertical inlet passage leading into the engine, and an outlet passage connected to the intake pipe through the inlet passage and a partition. The partition wall is provided with a small diameter orifice that communicates with the inlet passage and the outlet passage, and between the body and the cap, a diaphragm is inserted so that a predetermined distance is created between the diaphragm and the upper end opening of the outlet passage by the tension of the diaphragm itself. The lower end surface of the body is attached to the head cover so that the inlet passage communicates with the hole in the head cover of the engine, so that the blow-by gas flow path is narrowed when the engine is running at high speeds, but when the engine is running at low speeds. By widening the flow path, a nearly constant amount of blow-by gas that leaks into the engine can be smoothly returned to the intake pipe side without any problems, and there is no need for any other means of introducing outside air, and the inside of the engine is always maintained at atmospheric pressure. Since it is directly attached to the engine head cover without using a pipe, it improves workability in cramped spaces, saves installation space, and allows the configuration to be made smaller and more compact. Since the coil spring is not involved in the opening/closing operation of the diaphragm, it is easy to design and manufacture, and has the advantage of reducing the number of parts and reducing costs.

[Brief explanation of drawings]

FIG. 1A is a circuit side view showing the arrangement of a conventional reflux device. Figure B is a sectional view of the reflux device. FIG. 2 is a sectional view of another type of conventional reflux device. Third
The figure is a sectional view of an embodiment of the invention. Figure 4 is its plan view. In the diagram, 1...Body, 2...Cap, 3...
Entrance passage, 4...Exit passage, 5...Orifice,
6...Diaphragm, C...Head cover, Ca
...through hole.

Claims (1)

[Claims] 1 Consisting of a body and a cap covering the upper end of the body, the body has a vertical inlet passage leading to the inside of the engine, and an outlet passage connected to the intake pipe through the inlet passage and a partition, The partition wall is provided with a small diameter orifice that communicates with the inlet passage and the outlet passage, and between the body and the cap, a diaphragm is arranged to maintain a predetermined distance between the diaphragm and the upper end opening of the outlet passage by the tension of the diaphragm itself. 1. A blow-by gas recirculation device for an engine, characterized in that the blow-by gas recirculation device for an engine is mounted on a head cover with the lower end surface of the body communicating with the inlet passage through a hole in the head cover of the engine.