JPH0619783Y2 - Blow-by gas recirculation system for engines - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention introduces blow-by gas leaking into the engine into the engine and re-combusts it without releasing it into the atmosphere, mainly reducing hydrocarbons. To improve the blow-by gas recirculation system (PCV valve).

[Conventional technology]

Conventionally, as this kind of blow-by gas recirculation device, there has been one shown in FIGS. 5 to 8. That is, in the drawing, A is a body having a circular plane, which is mounted on the head cover of a diesel engine. Inside the body A, there is a vertically oriented inlet passage B aligned with a through hole of the head cover, and a partition wall C. Is provided with an L-shaped outlet passage D, and the outlet end is connected to an intake manifold (not shown) via a pipe E, and the partition wall C communicates with both passages B and D. A small-diameter orifice F is bored.

A diaphragm H is sandwiched between the body A and the cap G covering the body A at the peripheral edge thereof, and a ring-shaped seal portion 1 formed on the lower surface of the diaphragm H. Has an upper open end of the outlet passage D closed by a spring J disposed inside the cap G.

Therefore, when the engine is started and the engine is idling, the engine speed is just E as shown in FIG.
_This corresponds to the state of ₁ . At this time, the engine internal pressure P ₁ exhibits a positive (+) internal pressure, so that the diaphragm H is pushed up against the elastic force of the spring J by the engine internal pressure P _{1 as} shown in FIG. The upper open end is opened and most of the blow-by gas enters the outlet passage D through the open end and part enters the outlet passage D through the above-mentioned orifice F and into the intake manifold via the pipe E. I will be sucked in.

Then, as the engine operating speed increases, the intake manifold negative pressure P ₀ gradually increases, and the engine internal pressure P ₁ decreases due to the intake of blow-by gas into the intake manifold. Thus, the seventh
As shown in the figure, the diaphragm H is strongly sucked to close the upper opening end of the outlet passage D, and prevents the engine internal pressure P ₁ from decreasing like the intake manifold negative pressure P ₀ . At this time, the blow-by gas that has entered the inlet passage B of the head cover A will exclusively pass through the orifice F of the central partition C, and will flow into the intake manifold through the outlet passage D while its flow rate is throttled. Since the blow-by gas generated inside the engine is filled up and the engine internal pressure P ₁ is increased, the diaphragm valve is opened again as shown in FIG.

As described above, when the engine speed is between E _{1 and} E ₂ , the engine internal pressure P ₁ as a whole is controlled to a predetermined pressure by opening and closing the diaphragm valve as shown in FIG.

Further, when the engine speed exceeds E ₂ and is operated in a high region, the intake manifold negative pressure P ₀ becomes extremely large, and as shown in FIG. 7, the diaphragm valve is always closed. The blow-by gas is sucked into the intake manifold through the orifice F provided in the partition wall C.

Further, the engine speed is the maximum speed rotation region E ₂ to E _3, the blow-by gas by an intake manifold negative pressure P ₀ becomes to go sucked into the intake manifold through the orifice F, thus the engine internal pressure P ₁
Indicates a downward-sloping internal pressure, as shown in FIG. That is, the diaphragm H is to control the engine internal pressure P ₁ to a predetermined pressure by ON · OFF by opening pressure P _a more engine internal pressure P _1, also a large intake manifold negative pressure in an engine high rotation region When the diaphragm valve is fixed in the closed state, the small hole in the orifice controls the internal pressure of the engine almost in proportion to the negative pressure in the intake manifold.

[Problems to be solved by the invention]

However, the conventional blow-by gas recirculation apparatus as described above has the following drawbacks.

(1) Since the valve opening pressure Pa of the diaphragm valve is _a positive pressure, the internal pressure of the engine cannot be controlled by the negative pressure. (2) When the orifice diameter is increased, the number of times E
₂ moves to the low speed side, the engine negative pressure at the rotational speed E ₃ position becomes too large, and the amount of oil mist carried away to the intake manifold increases. (3) Rotational speed E ₁ ~
In between E _2, since the diaphragm is to control the vigorous open and close the engine pressure, there was sufficient strength to the diaphragm is that it is necessaryゝmonitor, resulting in cause damage risk is. (4) The internal pressure of the engine is appropriate to prevent leakage of blow-by gas from the inside of the engine to the atmosphere and leakage of engine oil to the atmosphere, and to minimize the amount of oil mist carried away to the intake manifold. Although it is desirable to control the negative pressure of, it could not be achieved by the conventional technology.

[Means for solving problems]

The present invention has been made to solve the above-mentioned conventional drawbacks, and when the engine internal pressure can be controlled with an appropriate negative pressure, it is possible to control the internal pressure without violently opening and closing the diaphragm valve. It is an object of the present invention to provide a blow-by gas recirculation apparatus for an engine, the gist of which is to provide an inlet passage for blow-by gas formed in a head cover and an intake manifold formed by interposing a partition wall in the head cover. A seal member that closes an outlet passage connected to the diaphragm with a diaphragm, has an orifice in the partition wall that communicates with both passages, and further has a notch between the upper opening end of the outlet passage and the diaphragm. And the cutout portion of the sealing member is changed by the pressure applied to the diaphragm. The blow-by gas feedback device for an engine is characterized in that so as to form a certain.

〔Example〕

The present invention will be described below with reference to the embodiments shown in FIGS. 1 is a vertical cross-sectional view of the blow-by gas recirculation system according to the present invention, FIG. 2 is a perspective view showing essential parts of parts used in the recirculation system, and FIG. 3 is an operating state of the recirculation system. FIG. 4 and FIG. 4 show the internal pressure characteristics of the reflux device.

In the figure, reference numeral 1 is a plane circular head cover, which is mounted on an engine (not shown). Inside the head cover 1, an inlet passage 2 communicating with the inside of the engine and an L-shaped outlet through a partition wall 3 are provided. A passage 4 is provided, and an outlet end of the passage 4 is connected to an intake manifold (not shown) via a pipe 5.

A small-diameter orifice 6 communicating with both the passages 2 and 4 is bored in the partition wall 3, and a required diameter is provided between the head cover 1 and the cap 7 covered on the head cover 1. While the diaphragm 8 is sandwiched at its peripheral portion, a ring-shaped sealing member 9 is formed in a protruding state at the central portion of the lower surface of the diaphragm 8, and a part of the circumference thereof is notched. It is part 10.

The sealing member 9 of the diaphragm 8 normally closes the upper opening end of the outlet passage 4 by the spring 11 arranged in the cap 7. The flow coefficient of the notch 10 changes depending on the pressure applied to the diaphragm 8, and the notch 10 forms a variable orifice. In the figure, 7a is an air inflow hole formed in the cap 7, and 11a is a spring seat.

Next, the operation will be described. When the engine is idling, that is, when the engine speed is just in the E ₁ state in FIG. 4, since the negative pressure P ₀ of the intake manifold is small, it is generated inside the engine. The blow-by gas pushes up the diaphragm 8 against the elastic force of the spring 11. As a result, the diaphragm 8
Since the sealing member 9 of is separated from the upper opening end of the outlet passage 4 and is in the open state, the blow-by gas enters the outlet passage 4 from the inlet passage 2 through the gap between the sheet member 9 and the upper opening end, and enters the intake manifold. I will be sucked in.

When the engine speed increases and the intake manifold negative pressure P ₀ increases, the diaphragm 8 is sucked and the seal member 9 of the diaphragm 8 is pressed against the upper open end of the outlet passage 4 as shown in FIG. When the engine speed exceeds E ₂ , the upper open end of the outlet passage 4 by the diaphragm 8 is closed.

Furthermore, when the engine speed rises above E ₂ ,
The blow-by gas generated inside the engine is sucked into the intake manifold through the cutout portion 10 of the diaphragm 8, and the internal pressure of the engine decreases. And
As the intake manifold negative pressure P ₀ increases,
As shown in FIG. 3, the diaphragm 8 and the sheet member 9
Is deformed. Thus, the notch portion 10 provided in the seal member 9 performs a throttling function by deformation, and becomes a variable orifice whose effective area is narrowed.

As a result, the engine internal pressure characteristic as shown in FIG. 4 can be obtained. That is, the seal member 9 attached to the diaphragm 8, the notch 10 is narrowed rotational speed of the engine is deformed seal member 9 in E _2, the engine rotational speed region E ₂ ~ the cutout portion 10 is narrowed At E ₃ , the throttle diameter of the cutout portion 10 changes in accordance with the increase of the intake manifold negative pressure P ₀ , and the engine internal pressure can always be controlled to an appropriate negative pressure. In the above example,
Although the seal member 9 is attached to the seal portion of the diaphragm 8, the same effect can be obtained even if the seal member 9 is provided on the seal portion of the other side that contacts the diaphragm 8.

[Effect of device]

As described above, the blow-by gas recirculation apparatus for an engine according to the present invention includes a blow-by gas inlet passage formed in the head cover and an outlet passage connected to an intake manifold formed with a partition wall in the head cover. In addition, the partition wall is provided with an orifice communicating with the both passages, and a seal member having a notch is provided between the upper opening end of the outlet passage and the diaphragm. Since the notch is configured to form the variable orifice by the pressure applied to the diaphragm, it becomes possible to control the internal pressure of the engine with an appropriate negative pressure, and prevent gas leakage and oil leakage from the engine. However, on the contrary, the inside of the engine becomes an excessive negative pressure and the oil is taken into the intake manifold. Or is drawn into the field, can be reliably prevented or cause the dust from entering the inside of the engine. Also, because the engine's rotational range in which the diaphragm opens and closes is only a very limited range, compared to the conventional model, in which the diaphragm opens and closes severely over the entire operating range of the engine, greatly affecting its life. Then, there are various effects that the durability of the diaphragm can be greatly improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a blow-by gas recirculation system according to the present invention, FIG. 2 is a perspective view showing essential parts of parts used in the recirculation system, and FIG. 3 is an operation state diagram of the recirculation system. 4 is an internal pressure characteristic diagram of the recirculation apparatus, FIGS. 5 to 7 are vertical sectional views showing an operating state of a conventional blow-by gas recirculation apparatus, and FIG. 8 is an internal pressure characteristic of the recirculation apparatus. 1 ... Head cover, 2 ... Entrance passage, 3 ... Partition wall, 4
...... Outlet passage, 6 …… Orifice, 7 …… Cap, 8
...... Diaphragm, 9 ... Seal member, 10 ... Notch, 11 ... Spring.

Claims (1)

[Scope of utility model registration request] 1. A blow-by gas inlet passage formed in a head cover and an outlet passage connected to an intake manifold formed by interposing a partition wall in the head cover are closed by a diaphragm, and the partition wall has the above-mentioned structure. A seal member having a notch is provided between the upper opening end of the outlet passage and the diaphragm, and the notch of the seal member is variable depending on the pressure applied to the diaphragm. An engine blow-by gas recirculation device characterized in that an orifice is formed.