JPS624530B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for introducing blow-by gas from a crank chamber, a cam chamber, or the like in an internal combustion engine into an intake system of the engine.

[Conventional technology and its problems]

Conventionally, blowby gas collected in a blowby gas reservoir such as inside the cylinder head cover of an engine is
For example, as described in Japanese Utility Model Publication No. 47-15084, etc., a flow rate control valve that operates to reduce intake negative pressure is used to control the flow rate so that it gradually increases as the engine load increases, and then introduces it into the engine's intake system. are doing. In this case, when the engine temperature is low, the combustion state of the engine is poor, and if blow-by gas is introduced in this temperature range, the combustion state of the engine will further deteriorate, and the drivability of the engine will be significantly reduced.

For this reason, in recent blow-by gas introduction devices, a temperature sensing valve is installed in the negative pressure transmission path of the intake negative pressure to the flow rate control valve, and the blow-by gas is not introduced into the intake system in areas where the engine temperature is low. Some proposals have been made to cut it.

However, if a relatively simple structure such as a bimetal type is used as the temperature sensing valve,
Although it is possible to reduce costs, it is not possible to completely block the negative pressure transmission passage of intake negative pressure,
Intake negative pressure is transmitted to the flow control valve by leakage in the temperature sensing valve, and the flow control valve opens and operates, so blow-by gas cut control is uncertain when the temperature is low, and the intake air If the temperature sensing valve were to have a structure that can completely block the negative pressure transmission passage, that is, a structure that does not leak, the temperature sensing valve would not only be extremely expensive and increase the cost, but also be large and require a lot of space for installation. It increases.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem when a temperature sensing valve is provided in a passage for transmitting negative intake pressure to a flow rate control valve in a blow-by gas introduction device.

[Means for solving problems]

To achieve this objective, the present invention provides a pressure-operated flow rate system in a blow-by gas return passage connecting a blow-by gas reservoir and an intake manifold in an engine, which is opened by negative pressure acting on a pressure chamber. A control valve is provided, the pressure chamber of the flow rate control valve is connected via a negative pressure transmission passage to a port provided at an appropriate location upstream of the closed position of the throttle valve of the carburetor, and a is provided with a temperature sensing valve that shuts off the negative pressure transmission passage when the temperature is low, while providing an atmospheric air leak means between the temperature sensing valve and the flow rate control valve in the negative pressure transmission passage. The configuration was set as follows.

[Effect]

That is, in this way, among the negative pressure transmission passages equipped with temperature sensing valves from the ports in the vaporizer to the pressure chambers in the flow rate control valves, a means for leaking atmospheric air is provided between the temperature sensing valves and the flow rate control valves. Therefore, when the temperature sensing valve closes, even if the intake negative pressure tries to be transmitted to the pressure chamber in the flow rate control valve due to leakage in the temperature sensing valve, atmospheric air leaks into this pressure chamber from the leak means. hand,
Since it is possible to prevent a large negative pressure from acting on the pressure chamber, it is possible to reliably prevent the blow-by gas flow rate control valve from opening when the temperature sensing valve is closed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, 1 is a cylinder block, 2 is a cylinder head, 3 is a cylinder head cover that covers the upper surface of the cylinder head 2, and 4 is a cylinder head 2.
A carburetor 5 with a throttle valve 17 and an air cleaner 6 are attached to the intake manifold 4, and camshafts for the intake and exhaust valves are installed in the upper chamber 18 of the cylinder head 2. 7 and swing arms 8, 9, etc., and blow-by gas from a crankcase (not shown) etc. accumulates in the upper chamber 18.

Reference numeral 10 denotes a blow-by gas gas-liquid separation chamber formed in the cylinder head cover 3, an inlet port 11 of which opens into an upper chamber 18 within the cylinder head 2, and an outlet provided with two outlet ports 12 and 13. One outlet port 12 is connected to a pipe 14 with an orifice 15 inserted in the clean side 13 of the air cleaner 6 at the upper position of the secondary side opening of the carburetor 5 through a passage such as a hose 16, and the other The outlet port 13 is connected to a blow-by gas introduction port 19 provided in the intake manifold 4 via a blow-by gas return passage 20.

Reference numeral 21 indicates a pressure-operated flow control valve such as a diaphragm provided in the blow-by gas return passage 20, and a valve body 23 that opens and closes the valve seat 22 in the control valve 21 is biased in the normally open direction by a spring 24. The valve body 23 has a diaphragm 2 defining a pressure chamber 25.
6 is in contact with the valve body 23, and the valve body 23 is pressed against the spring 24 by a spring 28 provided in the pressure chamber 25.
When negative pressure acts on the pressure chamber 25, the rod 27 is moved back against the spring 28, and the valve body 23 is opened by the spring 24. The pressure chamber 25 is connected to the closed position (idle opening degree) of the throttle valve 17 in the carburetor 5 via negative pressure transmission passages 29 and 30.
It is connected to a port 31 provided more appropriately upstream.

Further, 32 indicates a bimetallic temperature sensing valve provided between the negative pressure transmission passages 29 and 30, and the temperature sensing valve 32 is constructed as shown in FIG. 4. That is, the valve case is composed of two valve cases 33 and 34 that are caulked together, and a disc-shaped valve seat body 35 is installed between both valve cases 33 and 34, and the valve seat body 35 is One valve case 3
3, a ring-shaped valve seat 36 made of rubber or the like is provided on the outer periphery and a valve plate seat 37 made of rubber or the like is provided in the center, and the valve seat body 35 is provided with an annular valve seat 36 made of rubber or the like. Valve cases 33, 3 are located on the inner diameter side of 36.
4 is provided with a plurality of through holes 38 that communicate with each other. Further, a valve plate 39 made of a bimetal plate and formed into a downward dish shape is inserted into one of the valve cases 33, and the valve plate 39 is brought into contact with the annular valve seat 36 by a spring 40 inside the valve case 33. When the temperature becomes high, the valve plate 39 is reversed to curve upward into a dish shape as shown by the two-dot chain line, and opens the through hole 38. It is composed of

The temperature sensing valve 32 and the flow control valve 21
The negative pressure transmission passage 29 connecting the pressure chamber 25 of
One end is connected to the clean side 13 of the air cleaner 6.
An orifice 42 is provided in the leak passage 41 to minutely regulate the amount of atmospheric air leaked.

In this configuration, in the idling or low load range where the throttle valve 17 is fully open or close to fully closed, the port 31 is located upstream of the throttle valve 17 and no negative pressure is generated at the port 31, so the blow-by gas return passage The flow rate control valve 21 in 20 is not opened, and blow-by gas is not introduced into the intake manifold 4.

Next, in a partial load range when the throttle valve 17 is opened, negative pressure is generated at 31 ports. In this case, when the engine temperature is low, the temperature sensing valve 32 is closed and no negative pressure is transmitted to the flow control valve 21, so the flow control valve 21 does not open, but when the engine temperature has warmed up to a predetermined level, the temperature sensing valve 32 is closed. The valve 32 is opened, and the negative pressure at the port 31 is transferred to the pressure chamber 25 of the flow control valve 21.
This negative pressure causes the diaphragm 26 and the rod 27 to rise against the spring 28, and the valve body 23 opens away from the valve seat 24 by the spring 24. The blow-by gas inside is introduced into the intake manifold 4 through the return passage 20 and the port 19.

If there is a leak in the temperature sensing valve 32 when the temperature sensing valve 32 is closed and blow-by gas is being introduced, the negative pressure in the port 31 will be transmitted to the pressure chamber 25, causing the valve body 23 to open. However, in the present invention, the temperature sensing valve 32 is connected to the pressure chamber 25.
Since the leak passage 41 with an orifice 42 is connected to the negative pressure transmission passage 29 to Atmospheric air leaks from 41 in minute amounts to prevent an increase in negative pressure, so even if there is a leak when the temperature sensing valve 32 is closed, negative pressure will not be transmitted to the pressure chamber 25, and the flow rate control valve 21 will not malfunction.

In this case, the leak passage 41 may be connected to one valve case 33 of the temperature sensing valve 32 or the pressure chamber 25 of the control valve 21, and since the amount of atmospheric air leaking from this leak passage 41 is minute, the temperature sensing valve This prevents the port negative pressure transmitted to the pressure chamber 25 from decreasing when the valve 32 is opened.

The blowby gas collected in the blowby gas storage chamber such as the upper chamber 18 of the cylinder head 2 contains carbon, dust, etc.
There is a risk that the opening and closing operations of the valve body 23 may become impossible if the valve body 23 is attached nearby, but this problem can be solved by removing the lower surface of the valve body 23 on the valve seat 22 side, as shown in FIGS. 3 and 4. By carving a cross groove 43 in the valve body 23, a rod 44 having a diameter smaller than the inner diameter of the valve body 23 and inserted into the valve seat 22 with an appropriate gap to the inner surface of the valve seat is provided. , when the valve body 23 is closed, blow-by gas leaks little by little, and
When the valve body opens and closes, the rod body 44 rubs the inside of the valve seat 22 and scrapes off the carbon adhering to the inside of the valve seat 22 and the outer periphery of the rod body 44, thereby removing the adhesion of carbon, etc. contained in the blow-by gas. It is possible to prevent malfunction of the valve body due to this.

〔Effect of the invention〕

As described above, the present invention prevents the transmission of negative pressure to the blow-by gas flow rate control valve due to a small amount of atmospheric air leak in response to a leak when the temperature sensing valve is closed. Since the flow rate control valve does not malfunction when the valve is closed, it is possible to perform blow-by gas reduction control reliably and accurately.However, as a temperature sensing valve, it is possible to use a bimetal type etc. that leaks a little when the valve is closed. Since the temperature sensing valve may have a relatively simple structure, it is possible to reduce the cost and also to downsize the temperature sensing valve.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a diagram of the device of the present invention, FIG. 2 is an enlarged cross-sectional view of a main part of a flow control valve, FIG. 3 is a cross-sectional view taken from the side of FIG. 2, and FIG. is a cross-sectional view of a temperature sensing valve. 1... Cylinder block, 2... Cylinder head, 3... Cylinder head cover, 18... Cylinder head top chamber, 4... Intake manifold, 5
... vaporizer, 17 ... throttle valve, 20 ... blow-by gas return passage, 21 ... flow control valve, 2
5... Pressure chamber, 29, 30... Negative pressure transmission passage, 3
1...Port, 32...Temperature sensing valve, 41...Leak passage.

Claims (1)

[Claims] 1. A pressure-operated flow control valve that is opened by negative pressure acting on a pressure chamber is provided in the blow-by gas return passage that connects the blow-by gas reservoir and the intake manifold in the engine, and The pressure chamber is connected via a negative pressure transmission passage to a port provided appropriately upstream of the closed position of the throttle valve of the carburetor. An internal combustion engine characterized in that a temperature sensing valve for blocking the passage is provided, and an atmospheric air leak means is provided between the temperature sensing valve and the flow rate control valve in the negative pressure transmission passage. Blow-by gas introduction device.