JPS6145065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved carburetor that can supply an appropriate mixture ratio of air-fuel mixture to an internal combustion engine in response to external pressure that fluctuates with changes in altitude.

In general, even if the carburetor of an internal combustion engine is adjusted to the optimal mixture ratio in a lowland (land below sea level), when moving to a highland (land above sea level), the air density decreases due to the drop in outside pressure, causing the carburetor to This reduces the amount of air being sent in and increases the concentration of the air-fuel mixture more than necessary. On the other hand, if you adjust the mixture ratio to the optimum level at a high altitude and then move to a lower altitude, the amount of air sent to the carburetor will increase due to the increase in outside pressure, diluting the concentration of the air-fuel mixture. Therefore, in vehicles that travel back and forth between lowlands and highlands, if the proper mixture ratio of the carburetor is adjusted at lowlands, the mixture concentration at highlands will be increased and the throttle opening will be adjusted accordingly. There are problems that result in poor responsiveness between machines and insufficient output.

The present invention was made in view of the above-mentioned drawbacks of conventional vaporizers, and increases and adjusts the amount of bleed air sent to the vaporizer in response to changes in altitude (changes in outside pressure) from low altitudes to high altitudes. With this, the fuel flow rate is corrected and adjusted to the proper mixture, and when a certain altitude is exceeded, the main system fuel flow rate is switched from the low-altitude jet to the high-altitude jet with a lower flow rate, and at the same time the bleed air amount is throttled. By increasing and adjusting the amount of bleed air again, it is possible to supply the correct air-fuel mixture from the carburetor to the engine even in response to wide range of external pressure fluctuations from lowlands to highlands. This succeeded in preventing the mixture from becoming inappropriate due to changes in altitude and allowing the engine to always operate under the best conditions.

The present invention will be explained below with reference to embodiments shown in the drawings. In FIG. 1, 1 is an Amal type vaporizer, and air is sucked into this air flow path 2 from the direction of the arrow 3.
It leads to a gasoline internal combustion engine (not shown, hereinafter referred to as the engine). A piston-type throttle valve 4 faces the air passage 2 from above, and is moved up and down by operation of an accelerator wire _4b to adjust the opening amount of the air passage 2. 5 is a main bleed pulp stored in a vertical position in a float chamber 6, and a main nozzle _5a provided at the upper end of the main bleed pulp is suspended from the center of the bottom surface of the throttle valve 4 facing into the air flow path 2. The main jet 5 is fitted with the jet needle 4 _a to form the needle valve V, and is also fitted with the main jet 5 provided at the lower end of the main bleed pipe.
_b is immersed in fuel (gasoline) in the float chamber 6. 7 is a main air passage that supplies bleed air to the main bleed pipe 5;
This inlet is opened to the atmosphere side than the throttle valve 4, and the main air jet 7a _is located inside the passage.
is provided. Each of the above members 4 _a , 5 , 5 _a ,
_5b , 7, and _7a constitute the main system of the carburetor 1. On the other hand, the slow system of vaporizer 1 is
A bleed bleed pipe 8 is provided in the float chamber 6 close to the main bleed pipe 5,
The slow nozzle _8a at the upper end is opened near the lower end of the throttle valve 4 on the engine side, and the slow jet _8b at the lower end is immersed in the fuel in the float chamber 6.

The carburetor used in the present invention is constructed as described above, and the carburetor 1 is equipped with the altitude correction device H of the present invention as described below. First of all,
For the main jet 5 _b of the carburetor 1, a high altitude jet 9 that throttles the fuel flow rate and a bypass passage 10 are provided in the float chamber 6, and a main system fuel flow rate switch operated by a diaphragm 11 is provided in the bypass passage 10. The switching valve V ₁ is provided with a valve V 1 , and the switching valve V ₁ is opened by the elastic force of a spring 12 housed in a diaphragm 11 . That is, in the illustrated state (low altitude), the fuel in the float chamber 6 is sent to the main jet _5b through the high altitude jet 9 and the bypass passage 10, so the fuel flow rate sucked up by the main nozzle _5a is The main jet that serves as a lowland jet.
controlled by jet 5 _b and directional valve V ₁
When the high altitude jet 9 is closed, the fuel flow rate is restricted by the high altitude jet 9. V ₂ is an air valve that communicates the engine side with the throttle valve 4 of the carburetor 1 and the atmosphere side through a passage 13, and is closed by the elastic force of the spring 15 of the diaphragm 14 at low altitudes. ing. 16 is a passage communicating with the air flow passage 2 on the engine side, and there is a check valve 17 and a throttle part 1 on the way.
The tip of the diaphragm 1 provided with the diaphragm 8 operates the main system fuel flow rate switching valve V ₁ and the air valve V ₂ .
It is connected to each passage 19, 20 communicating with each negative pressure chamber _11a , _14a of No. 1, 14, and is connected to a pressure switching valve _V3 of an external pressure detection member ED, which will be described later. 21
is a passage whose one end is connected to the back of the main air passage 7, and this tip is connected to the bleed air control valve _V4 of the external pressure detection member ED.

Next, details of the external pressure detection member (altitude detection member) ED will be explained. 30 is a pressure sensitive bellows for detecting external pressure (altitude) filled with vacuum or nitrogen or argon gas, and this base end bolt 31 is connected to the housing 32.
It is screwed onto the right end wall _32a and secured by tightening with a lock nut 33. and pressure sensitive bellows 3
The inside of the housing ₃₂ is communicated with the outside air through the passage 22 so that the free end 30a of the housing 32 expands and contracts back and forth in response to changes in outside air pressure (altitude). 34
is a rod attached to the free end _30a of the pressure sensitive bellows 30, the tip of which is supported in the bearing hole 35 and protrudes a small amount into the cavity S. A boss 36 of a pressure switching valve V ₃ is fitted to the right side of the middle collar 34 _a of the rod 34 so as to be slidable only in the axial direction, and the pressure sensitive bellows 3
The diaphragms 11, ₁₄ are brought into contact with the middle collar _34a by the weak elastic force of the coil spring 37 interposed between the free end 30a of the diaphragm 11 and the free end 30a of the diaphragm 11, A passage 23 connected to the air passage 2 and the air passage 2 is opened to the outside air. with this,
While the pressure switching valve V ₃ is open, the main system fuel flow switching valve V ₁ is open and the air valve V ₂ is closed, so that air is introduced into the air flow path 2 from the passage 16. . Reference numerals 38 and 39 denote diaphragms provided on the left and right sides in the cavity S. A washer 40 having a protrusion 40 _a and a flat washer 41 are fixed to the right diaphragm 38 with a rivet 42 , and the right end of the rivet 42 is attached to the rod 34 . is always in contact with the tip of the The right chamber S ₁ of the diaphragm 38 is connected to the through hole 24.
maintained at outside pressure by the two diaphragms 3
The central chamber S ₂ sandwiched between 8 and 39 is connected to each passage 16 and 1.
9, 20, and 23, and the pressure-sensitive bellows 30 is contracted to open the pressure switching valve _V3 , and the pressure is maintained at outside pressure as shown in the figure. On the other hand, the left diaphragm 39 has a support rod 43 _a on the right side.
A rivet ₄₃ with
A coil spring 47 with a relatively strong elastic force that does not contract due to the pressing force of the pressure-sensitive bellows 30 but contracts due to the negative pressure of the air flow path 2 (central chamber S ₂ ) is compressed between the rod 43 and the rod 43. The disk 46 near the right end of _a is brought into contact with the protrusion _40a of the diaphragm 38. Expansion 2 of passage 22 located to the left of diaphragm 39
The bleed air control valve V ₄ housed in 2 _a has its left end connected to the support hole 2 so that it coaxially faces the rivet 43.
The communication hole _22c of the left side chamber _S3 , which is supported by the left side chamber S3 and connects the expansion part _22a and the passage 21 by means of a spring 48 with a weak elastic force, is on _the verge of closing at the tapered surface 49 in the low-lying state shown in the figure. I've narrowed it down to. The control valve V ₄ is now adjusted to open and close in accordance with the expansion and contraction of the pressure-sensitive bellows 30. The operational relationships of the valves V ₁ to _{V 4} with respect to changes in external pressure (altitude) are set as shown in FIG. 2. That is, as the altitude of the vehicle is gradually increased from lowland _N1 , the pressure-sensitive bellows 30 is expanded so that the fuel correction curve b is placed on the curve a of the required fuel flow rate Q of the engine by increasing the amount of bleed air. - Gradually open air control valve _V4 . The pressure switching valve V ₃ is closed near the altitude N ₂ where the control valve V ₄ is fully opened, and the negative pressure in the diaphragm central chamber S ₂ is thereby closed, and the main system fuel flow switching valve V 1 is closed, and the main system fuel flow switching valve V ₁ is closed. - Throttle the fuel flow rate _Q2 from jet _5b to high altitude jet 9 from C to C', and introduce secondary air into the air passage 2 through the opening of air valve _V2 . On the other hand, by reducing the pressure in the central chamber _S2 , the coil spring 47 is compressed and the bleed air control valve _V4 is again throttled down to the low altitude condition, and the section from altitude _N2 to _N3 is converted into a curve a of the engine's required fuel flow rate Q. The pressure-sensitive bellows 30 operates the bleed air control valve _V4 so that the fuel correction curve b' is set by increasing the amount of bleed air.

The altitude correction device H of the present invention is configured as described above, and corrects the air-fuel mixture in the carburetor 1 in the following manner. First, when the vehicle is at low ground _N1 , as shown in FIG.
_0a is contracted to the maximum, opening the pressure switching valve _V3 and greatly restricting the bleed air control valve _V4 . As a result, the negative pressure chamber 11 of each diaphragm 11, 14
_a , _14a are maintained at outside pressure, the main system fuel flow switching valve _V1 is opened and the fuel flow rate is controlled by the main jet _5b for lowland use, while the air valve _V2 is closed and the air flow path 2 It is in a position to introduce secondary air from the passage 16 to the bleed air passage 7, and the amount of bleed air to the bleed air passage 7 is greatly reduced. At this time, the required fuel flow rate Q (the throttle valve 4 of the carburetor is at a constant opening) is determined by the throttled bleed flow rate as shown in Figure 2.
It is given as the maximum value of curve a by curve b of fuel correction _Q1 by air and set value C of fuel flow rate correction _Q2 by main jet _5b . As the altitude of the vehicle gradually increases, the free end 30a of the pressure-sensitive bellows ₃₀ stretches against the elastic force of the spring 48.
Gradually open the bleed air control valve V ₄ ,
Bleed on the curve a of the engine's required fuel flow rate Q.
The fuel correction curve b obtained by increasing the amount of air is used to automatically adjust the mixture sent from the carburetor 1 to the engine to always have the optimum mixture ratio. As shown in FIG. _{3, near the altitude N 2} where the bleed air control valve V ₄ is fully opened, the pressure switching valve V ₃ closes, and at the same time, the negative pressure chamber ₁₁ a of each diaphragm 11, 14 opens. , 14 _a and the central chamber S ₂ of the diaphragms 38 and 39 become negative pressure in the air flow path 2 . As a result, the air valve V ₂ opens and secondary air is introduced directly into the air flow path 2, and the main system fuel flow rate switching valve V ₁ closes and the air is transferred from only the high altitude jet 9 to the main jet 5 _b . As shown in Figure 2, fuel is sent with the fuel flow rate reduced to the set value C'. Also, the left diaphragm 39 springs 47 due to the negative pressure in the central chamber _S2 .
, and move it to the pressure sensitive bellows 30 side, and then throttle the bleed air control valve V ₄ again to the low altitude state N ₁ . As a result, the amount of bleed air in the main system is reduced all at once, canceling out the influence of fluctuations in the required fuel flow rate Q due to the greatly reduced set value C' of the main system fuel flow rate, and changing the curve from curve a to a'. I can ride it without any trouble. As the vehicle speed further increases from this state, the free end _30a of the pressure-sensitive bellows 30 closes _V3 as shown in FIG. The bleed air control valve V ₄ is gradually opened again via the rod 34 and rivets 42 and 43, and the altitude is increased.
Even in the range _N2 to _N3 , the fuel correction curve b' obtained by increasing the amount of bleed air can be placed on the curve a' of the required fuel flow rate Q of the engine. This will increase the amount of bleed air and compensate for the decrease in fuel flow rate as the altitude increases.
The air-fuel mixture sent from the aircraft to the engine is automatically adjusted to the optimal mixture ratio regardless of altitude fluctuations.
In addition, in a slow system, the air density decreases as the altitude increases, so even if the idling opening of the carburetor 1 is constant, the mixture concentration increases, or the idling speed decreases due to a decrease in the amount of intake air, etc. However, in the area between altitude N ₂ and N ₃ , the air valve V ₂
The secondary air is introduced into the air flow path 2 through the opening of the
This optimizes the mixture ratio and prevents a drop in idle speed. When the vehicle moves from the highland _N3 to the lowland _N1 , each valve _V1 to _V4 is adjusted so that the fuel flow rate is increased along the curve a'→a of the required fuel flow rate Q.
will operate in the opposite direction.

As explained above, the required fuel flow rate correction corresponding to each altitude is performed by adjusting the bleed air amount by switching the main system fuel flow rate. In addition to having the advantage of being able to correct the altitude of the carburetor 1 over an altitude difference range that is twice as large as when correcting the flow rate, the bleed air amount can be adjusted again around the switching point _N2 of the main system fuel flow rate. 2 of the ideal curves a and a' of the required fuel flow rate Q.
The fuel correction curves b and b' due to bleed air can be matched to the ideal curves a and a' at certain points, making it possible to correct the fuel flow rate with little deviation even though the fuel flow rate correction is performed over a wide range. There are advantages that can be achieved.

Note that the present invention is not limited to the above-mentioned embodiment, and the design of each part can be changed. For example, the pressure switching valve _V3 is not limited to an on-off valve with hysteresis, and the type of the vaporizer 1 is not limited to the Amal type.

According to the present invention, since the structure is as described above,
Compared to the case where the fuel flow rate is corrected by simply adjusting the amount of bleed air, it is possible to correct the altitude of the carburetor over twice the altitude difference range, and the bleed air can be used at two points on the ideal curve of the required fuel flow rate. Since the fuel correction curves can be matched, excellent effects can be achieved, such as making it possible to perform fuel flow rate correction with little deviation even though the fuel flow rate correction is performed over a wide range.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an Amal type carburetor equipped with the present invention, Fig. 2 is an action diagram showing the fuel flow rate correction state corresponding to altitude, and Figs. 3 and 4 are system diagrams showing the operating state of each member. It is. 1... Carburetor, 2... Air flow path, 5... Main bleed pipe, 5 _b ... Main jet, 7... Bleed air passage, 9... High altitude jet, 11, 14, 38 , 39... diaphragm, 13, 16, 21, 22, 23... passage, 3
0...Pressure sensitive bellows, V ₁ ...Main system fuel flow switching valve, V ₂ ...Air valve, V ₃ ...Pressure switching valve, V ₄
...Bleed air control valve, ED...External pressure detection member.

Claims (1)

[Claims] 1. A fuel flow rate switching valve is installed in the main system fuel passage to switch between low-altitude jet and high-altitude jet.
While connecting this to the external pressure operating member, a bleed air control valve is provided in the bleed air passage that increases the opening degree as the external pressure decreases.
An external pressure-responsive member that expands and contracts in response to the operation of the external pressure-responsive member is interposed in the middle of the member that connects the air adjustment valve and the external pressure-responsive member, and the bleed air is adjusted by the expansion and contraction of the external pressure-responsive member. A carburetor altitude correction device configured to be able to adjust the initial opening degree of the valve.