JPH07166896A - Air governor - Google Patents

Abstract

PURPOSE:To improve startability and throttle response while restricting a maximum rotational speed of an engine by providing a governor in an intake system communicating with an intake port of the engine, and adjusting an intake air flow amount in the downstream of a carburetor. CONSTITUTION:Even when a negative pressure of an intake passage is introduced to a control cylinder 20 through the third air passage 21, a control piston 22 is energized by a return spring 23, to stay in a side of the second air passage 10, and the third air passage 21 is interrupted, to also introduce the atmosphere to the second chamber 11b through the second air passage 10. In accordance with a differential pressure from a negative pressure introduced to the first chamber 11a through the first air passage 9, a stabilizer piston 13 is energized to a side of the first air passage 9. As a result, at start time and at intermediate speed low load operation time with a high negative pressure in the intake passage, a governor valve 7 is made inoperative, and in accordance with increasing an engine speed (governor valve 7 closes intake passage) the maximum rotational speed is restricted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air governor for controlling the maximum engine speed, and more particularly to a technique for optimizing its operating range.

[0002]

2. Description of the Related Art In many industrial vehicles such as forklifts for premises, the upper limit of vehicle speed is set from the viewpoint of safety. Therefore, the gasoline engine used for this purpose is provided with an air governor in order to keep the maximum engine speed below the set value regardless of the throttle opening.

As shown in FIG. 5, an air governor 1 is interposed downstream of a throttle valve 3 of a carburetor 2 in an intake system, and an intake passage 5 in a governor body 4 is driven by a vacuum actuator 6 which governs a governor valve 7.
To open and close. The governor valve 4 is a butterfly type, like the throttle valve 3, and is rotatably attached to the intake passage 5 via a valve shaft 8.

The vacuum actuator 6 includes a governor cylinder 11 whose left and right ends communicate with the intake passage 5 and an air cleaner (atmosphere) (not shown) through the first and second air passages 9 and 10, respectively, and the inside of the governor cylinder 11. Slidably fitted in the first chamber 11a on the side of the first air passage 9
And a stabilizer piston 13 which is partitioned into a second chamber 11b on the side of the second air passage 10 and which is connected to the governor valve 7 via a rod 12. In FIG.
Reference numeral 14 is a tension coil type valve spring for urging the governor valve 7 in the opening direction, 15 is a choke valve provided upstream of the throttle valve 3, and 16 is an idle nozzle. Further, 17 is a pipe connected to the air cleaner, and 18 is a cover defining the governor cylinder 11. Since the governor cylinder 11 is expanded on the side of the second chamber 11b, the second air passage 10 is not closed even when the stabilizer piston 13 moves to the right side in the drawing.

In the air governor 1, the stabilizer piston 13 is arranged in FIG. 5 according to the differential pressure between the intake negative pressure (hereinafter simply referred to as negative pressure) in the intake passage 5 and the atmospheric pressure and the spring force of the valve spring 14. It moves in the left-right direction and drives the governor valve 7 in the opening or closing direction. For example, even when the throttle opening is constant, if the engine load increases when a heavy object is loaded or when traveling on an uphill road, the engine speed decreases and the negative pressure also decreases. In this case, the pressure difference between the left and right of the governor cylinder 11 becomes small, and the urging force due to the differential pressure acting on the stabilizer piston 13 naturally becomes small, and the governor valve 7 urged by the valve spring 14 becomes smaller.
Rotates in the opening direction. In this case, the intake air flow rate depends only on the opening degree of the throttle valve 3, and the operator (driver)
If the throttle lever or the like is operated, the engine speed and the output increase or decrease according to the operation amount.

On the other hand, even if the throttle opening is constant, if the engine load becomes small when there is no load or when the vehicle runs flat,
Contrary to the front, the engine speed increases and the negative pressure also increases. Then, in the governor cylinder 11, the pressure difference between the first chamber 11a communicating with the intake passage 5 and the second chamber 11b communicating with the atmosphere increases, and the urging force due to the differential pressure acting on the stabilizer piston 13 also increases. As a result, the stabilizer piston 13 moves to the left in FIG. 5, and overcomes the urging force of the valve spring 14 to rotate the governor valve 7 in the closing direction. In this case, since the upper limit of the intake flow rate is regulated by the governor valve 7 whose opening degree increases with negative pressure, even if the operator operates the throttle lever or the like to the open side, the engine speed becomes equal to or higher than the set value. Don't

[0007]

As is well known, when the temperature of the engine is low and the engine is cold, the vaporization rate of the fuel is poor, so that a mixture richer than usual is required. Therefore, when starting the engine, a large amount of fuel is discharged from the idle nozzle 16 by closing the choke valve 15 as shown by the chain double-dashed line and then cranking it to increase the negative pressure. However, when the air governor 1 is provided in the intake system, the governor valve 7 is closed due to a large negative pressure, and the negative pressure on the downstream side of the governor valve 7 increases, but the negative pressure on the upstream side where the idle nozzle 16 is installed is increased. The pressure becomes smaller. As a result, the amount of fuel discharged from the idle nozzle 16 is reduced, the concentration of the air-fuel mixture is reduced, and starting is extremely difficult.

On the other hand, the air governor 1 is, as described above,
Although it is provided in order to regulate the maximum engine speed, there is a problem that the air governor 1 operates even during medium speed operation and deteriorates the accelerator response.
That is, during medium speed low load operation, the engine speed corresponding to the opening degree of the throttle valve 3 is high, so the governor valve 7 is driven in the closing direction by the increased negative pressure, and the opening degree of the governor valve 7 is increased. Is smaller than the opening. In such a case, the operator cannot obtain the intended output and is forced to further operate the throttle valve 3 to the open side to reduce the negative pressure when performing acceleration or the like. Further, even if the throttle valve 3 is opened, there is a time lag until the differential pressure decreases and the governor valve 7 opens. Therefore, the intake flow rate does not immediately increase and the throttle response is significantly deteriorated.

The present invention has been made in view of the above situation, and an object of the present invention is to provide an air governor which does not operate at the time of starting or at a medium speed operation.

[0010]

In order to achieve the above object, an air governor of the present invention is provided in an intake system which communicates with an intake port of an engine, and adjusts an intake flow rate on a downstream side of a carburetor to provide an engine. An air governor for controlling the maximum number of revolutions of the governor, which is provided in an intake passage formed in the governor body and opens or closes the intake passage, and a valve urging means for urging the governor valve in the opening direction, One end communicates with the upstream side of the governor valve in the intake passage via the first air passage,
A governor cylinder whose other end is open to the atmosphere through a second air passage, and slidably fitted in the governor cylinder,
The governor cylinder is divided into a first chamber on the side of the first air passage and a second chamber on the side of the second air passage, and is connected to the governor valve via a connecting member. When moving to the side of the first air passage. A stabilizer piston that drives the governor valve in the closing direction, and drives the governor valve in the opening direction when moving to the second air passage side, and one end of the stabilizer piston in the intake passage upstream of the governor valve through a third air passage. A control cylinder, which communicates with the other end intersecting with the pipe of the second air passage, is slidably fitted in the control cylinder, and is urged toward the second air passage by a spring. When moving to the passage side, the third air passage is blocked and the second air passage is communicated. When moving to the third air passage side, the second air passage is blocked and the second air passage is blocked. Characterized in that comprises a control piston which communicates with the the air passage second chamber.

[0011]

In the air governor of the present invention, the choke valve is introduced into the control cylinder through the third air passage at the time of start-up and at the time of medium speed and low load operation in which the throttle valve is slightly opened or half opened. When the negative pressure becomes larger than a predetermined value, the spring force of the spring is overcome and the control piston moves to the third air passage side. Then, the second air passage is blocked by the control piston, the third air passage is communicated with the second chamber of the governor cylinder, and the differential pressure between the first chamber and the second chamber of the governor cylinder becomes zero. As a result, the stabilizer piston can freely slide in the governor cylinder, and the governor valve biased by the valve biasing means opens the intake passage.

On the other hand, during high speed operation, the negative pressure does not increase so much because the opening of the throttle valve is relatively large. Therefore, even if the negative pressure is introduced into the control cylinder through the third air passage, the control piston is biased by the spring and stays on the second air passage side, and the third air passage is blocked and the second air passage is blocked. The air passage is communicated. Therefore, the atmosphere is introduced into the second chamber of the governor cylinder through the second air passage.
The stabilizer piston is biased toward the first air passage side in accordance with the differential pressure from the negative pressure introduced into the first chamber via the air passage. As a result, like the conventional device, the governor valve closes the intake passage in accordance with the increase in the engine speed, and the maximum speed is restricted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an air governor according to the present invention will be described below with reference to the drawings. In the description of the embodiments, the same members as those of the conventional device described above are designated by the same reference numerals, and the duplicated description will be omitted. As shown in FIG. 1, the air governor 1 of the present embodiment is also installed downstream of the carburetor 2 as in the conventional device, and is of a butterfly type in which the intake passage 5 in the governor body 4 is driven by a vacuum actuator 6. The structure is such that the governor valve 7 opens and closes. The governor valve 4 is rotatably attached to the intake passage 5 via a valve shaft 8 and is biased in the opening direction by a valve spring 14 which is a valve biasing means.

The vacuum actuator 6 is composed of a governor cylinder 11 and a stabilizer piston 13. The left end of the governor cylinder 11 communicates with the intake passage 5 through the first air passage 9, and the right end thereof is the second air hole that is perforated downward. It communicates with an air cleaner (not shown) through the passage 10. Further, the stabilizer piston 13 is slidably fitted in the governor cylinder 11, and
The first chamber 11a on the first air passage 9 side and the second air passage 10
Side second chamber 11b and the governor valve 7
Is connected via a rod 12.

On the other hand, as shown in FIG. 2 (enlarged view of portion A in FIG. 1), a control cylinder 20 is formed below the governor body 4 in parallel with the governor cylinder 11. The left end of the control cylinder 20 communicates with the intake passage 5 near the upper end of the valve body 4 via the third air passage 21, and the right portion intersects with the second air passage 10. A columnar control piston 22 is fitted in the control cylinder 20 and freely slides in the left-right direction in the drawing, and also has a return spring 23.
Is urged toward the second air passage 10 side.

An annular groove 24 is formed in the control piston 22 at a substantially central portion in the axial direction. Then, when the control piston 22 comes into contact with the cover 18, as shown in FIG.
As shown by the solid line inside, the annular groove 24 and the second air passage 1
0 has the same phase in the axial direction, and the second air passage 10 is communicated. A small-diameter orifice 25 and a large-diameter communication hole 26 are sequentially formed between the second chamber and the control cylinder 20 from the second air passage 10 side toward the third air passage 21 side. In the lower part of the control cylinder 20, from the opening position of the orifice 25 to the third air passage 21
The communication groove 27 extends in the axial direction toward the side. Therefore, when the control piston 22 moves to the side of the third air passage 21 as shown by the broken line in FIG. 2, the second air passage 10 is blocked by the control piston 22, while the annular groove 24 and the communication hole 25 and The communication groove 27 has the same phase in the axial direction, and the third air passage 21 and the second chamber 11b of the governor cylinder 11 communicate with each other. The governor cylinder 11 has a diameter increased on the second chamber 11b side, as in the conventional device. Therefore, as shown by the chain double-dashed line in FIG. 2, even when the stabilizer piston 13 moves to the right side in the figure, not only the second air passage 10 but also the orifice 2
5 and the communication hole 26 are not closed either.

The operation of this embodiment will be described below. At the time of start-up when the choke valve 15 is closed, the negative pressure in the intake passage 5 of the air governor 1 becomes very large due to the cranking, that is, the negative pressure suction caused by the lowering of the piston.
Since this negative pressure is introduced into the control cylinder 20 via the third air passage 21, as shown in FIG. 3, the control piston 22 overcomes the spring force of the return spring 23 and the control piston 22 moves to the third air passage 21. Move to the side.

Then, the control piston causes the second
The air passage 10 is blocked, and the third air passage 21 and the governor cylinder 1 are connected via the communication groove 27 and the annular groove 24.
The 1st 2nd chamber 11b is connected. Then, the differential pressure between the first chamber 11a and the second chamber 11b, to which the negative pressure of the intake passage 5 is constantly introduced via the first air passage 9, becomes 0, and the stabilizer piston 13 is freely moved inside the governor cylinder 11. It slides and is urged by the valve spring 14 to fully open the governor valve 7. As a result, a large amount of fuel is discharged from the idle nozzle 16 on which a large negative pressure acts as it is, and a good start with a rich air-fuel mixture becomes possible.

Further, even when the throttle valve is in a small open state or a half open state at a medium speed and low load operation, the negative pressure in the intake passage 5 of the air governor 1 increases as the engine speed increases. Then, when the value of the negative pressure introduced into the control cylinder 20 through the third air passage 21 becomes larger than a predetermined value, the spring force of the return spring 23 is overcome and the control piston 22 moves toward the third air passage 21 side. Move to. Also in this case, the pressure difference between the first chamber 11a and the second chamber 11b becomes 0 and the governor valve 7 urged by the valve spring 14 is fully opened in the same procedure as at the time of starting. Therefore, the intake air flow rate depends only on the opening degree of the throttle valve 3, and the output as desired by the operator is obtained and the throttle response is improved.

During the medium speed and low load operation, the control piston 22 moves according to the negative pressure in the intake passage 5, so that the governor valve 7 operates in the opening or closing direction at a predetermined engine speed. . Therefore, when the engine is operated at a predetermined speed, a so-called hunting phenomenon may occur in which the governor valve 7 repeatedly opens and closes due to rattling of the drive system of the throttle valve 3 and the like. However, in this embodiment, since the orifice 25 is formed between the second air passage 10 and the communication hole 26, the stabilizer piston 13 is prevented from moving rapidly due to the fluctuation of the engine rotation, and the hunting phenomenon is almost ignored. I was able to fit within the range I could.

On the other hand, during high speed operation in which the throttle valve 3 is fully opened, the intake resistance is small, so the negative pressure in the intake passage 5 of the air governor 1 is relatively small. Therefore, even if this negative pressure is introduced into the control cylinder 20, as shown in FIG.
2 is biased by the return spring 23 and remains in contact with the cover 18.

In this state, as described above, the second air passage 10 is inserted through the annular groove 24 of the control piston 22.
And the orifice 25 and the communication hole 26 are simultaneously blocked by the control piston 22. Therefore, the negative pressure of the intake passage 5 is introduced into the first chamber 11 a of the governor cylinder 11 via the first air passage 9, and the second chamber 1 a
Atmosphere is introduced into 1b through the second air passage. As a result, the stabilizer piston 13 moves to the first air passage side according to the negative pressure in the intake passage 5 to drive the governor valve 7 in the closing direction, and the maximum engine speed is regulated as in the conventional device. Of.

Although the description of the specific embodiment has been completed, the embodiment of the present invention is not limited to this embodiment. For example, although the governor valve is a rotary butterfly type in the above embodiment, it may be a sliding flat type. Also,
A compression coil spring, a coil spring, or the like may be used as the valve urging means, or an air spring or the like may be used. Further, the shapes of the air passages, the control pistons, and the like may be appropriately changed without departing from the scope of the present invention due to design or manufacturing reasons. Further, in the above embodiment, the second chamber side of the governor cylinder is expanded in diameter so that the second air passage and the communication hole are not closed by the stabilizer piston, but a groove is formed in the lower portion of the stabilizer piston. Therefore, the same action may be obtained.

[0024]

According to the air governor of the present invention, since the governor valve is prevented from being operated at the time of starting when the negative pressure in the intake passage becomes high or at the time of operation at medium speed and low load, the startability is controlled while limiting the maximum engine speed. And throttle response can be improved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part showing an intake system to which an air governor according to the present invention is attached.

FIG. 2 is an enlarged view of part A in FIG.

FIG. 3 is an explanatory view showing the operation of the air governor according to the present invention.

FIG. 4 is an explanatory view showing the operation of the air governor according to the present invention.

FIG. 5 is a longitudinal sectional view of an essential part showing an intake system to which a conventional air governor is attached.

[Explanation of symbols]

 1 Air Governor 2 Carburetor 3 Throttle valve 4 Valve body 5 Intake passage 6 Vacuum actuator 7 Governor valve 9 1st air passage 10 2nd air passage 11 Governor cylinder 12 Rod 14 Governor spring 15 Choke valve 16 Idle nozzle 20 Control cylinder 21 3rd air passage 22 control piston 23 return spring 24 annular groove 25 orifice 26 communication hole 27 communication groove

Claims (1)

[Claims] 1. An air governor which is provided in an intake system communicating with an intake port of an engine and regulates a maximum engine speed by adjusting an intake flow rate on a downstream side of a carburetor, the air governor being formed in a governor body. A governor valve that is provided in the intake passage and opens or closes the intake passage, a valve urging unit that urges the governor valve in the opening direction, and one end of the governor valve in the intake passage upstream of the governor valve through the first air passage. A governor cylinder, which is in communication with the other end of the governor cylinder and is open to the atmosphere through the second air passage, is slidably fitted in the governor cylinder, and the governor cylinder is connected to the first chamber on the first air passage side and the first chamber. 2 It is divided into a second chamber on the air passage side and is connected to the governor valve through a connecting member, and the governor valve is closed when moving to the first air passage side. A stabilizer piston that drives the governor valve in the opening direction when moving to the second air passage side, and has one end communicating with the upstream side of the governor valve in the intake passage through the third air passage, and the other. A control cylinder whose end intersects the pipeline of the second air passage, and a control cylinder that is slidably fitted in the control cylinder and is urged toward the second air passage by a spring to move toward the second air passage. When moving, the third air passage is blocked and the second air passage is communicated, and when moving to the third air passage side, the second air passage is blocked and the third air passage and the second chamber are connected. An air governor featuring a control piston that communicates.