JPS60159358A - Fuel supply device for liquefied-petroleum-gas engine - Google Patents

Abstract

PURPOSE:To make a stable fuel feed attainable all the time, by installing a primary chamber, which decompresses LPG fuel, and a vaporizer having a secondary chamber, which is connected to the former via an interconnecting passage and further decompresses the said fuel, while varying internal pressure in the primary chamber according to a degree of engine load. CONSTITUTION:A vaporizer 4, where a fuel delivery part is connected to a fuel feed port 3 opened to a Venturi part 2a of an LPG engine's mixer 2, is provided with a casing 6 whose inside is partitioned into two parts, namely, a primary chamber 9 and a secondary chamber 10 by a partition wall 8 having a warm water passage 7. The primary chamber 9 is connected to an LPG cylinder via a port 12 to be opened or closed by a primary valve 13. In this case, this primary valve 13 is controlled by a primary pressure regulating device 19, which controls a spring 20 for its pressing force against a diaphragm 17 and regulates internal pressure in the primary chamber 9, via a lever 15. And, this regulating device 19 is constituted to be controlled by dint of excitation of a solenoid 52 so as to cause the internal pressure of the primary chamber 9 in time of engine low load to be lowered down to some extent as compared with that in time of high load.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention vaporizes liquefied petroleum gas, abbreviated as LPG, under reduced pressure, and further regulates the pressure to provide an engine with an air-fuel ratio that is appropriate for its operating condition. The present invention relates to a fuel supply device for an LPG engine configured to be able to supply a large amount of fuel.

(Prior Art) In a fuel supply system for an LPG engine, a mixer (mixer) is generally installed between an LPG cylinder for fuel storage and an intake passage of the engine to regulate the pressure of LPG fuel from the LPG cylinder. A pressure regulating device called a vaporizer is interposed to supply the vapor to the vaporizer.

This vaporizer includes a primary chamber, a secondary chamber connected to the primary chamber via a communication path, and a valve that opens and closes the communication path to measure the amount of fuel introduced from the primary chamber to the secondary chamber. LP supplied from an LPG cylinder.
G fuel is depressurized in the primary chamber until it becomes a constant gas, and then further depressurized to approximately atmospheric pressure in the secondary chamber, and the venturi negative pressure of the mixer installed in the intake passage allows the engine's intake air to flow from the secondary chamber. A two-stage decompression type for supplying pressure to a passage is well known.

In such a two-stage pressure reducing vaporizer, the valve member that opens and closes the communication passage between the primary chamber and the secondary chamber is operated when the operating state of the engine, including the idling state, is in the low-load operating range. For example, the valve gap should be expanded to form a minute valve gap of about 40 μm, and when transitioning from a low-load operating range to a high-load operating range, the valve clearance should be expanded to appropriately follow the increase in engine load. It is required that the settings be made so that the However, in such a setting, adjustment of the valve member to stably form a minute valve gap becomes difficult as the valve gap becomes smaller, and the workmanship and assembly of the valve member and its related components becomes more difficult. Prevent the effects of accuracy, and the greater degree of influence from external disturbances such as minute vibrations and shocks, and avoid interfering with the operation of expanding the valve gap to follow the increase in engine load. It is extremely difficult to achieve both the operation of stably forming a minute valve gap in the valve member and the operation of expanding the valve gap by appropriately following the increase in engine load. It is difficult to force them to do so. Therefore, when the engine operating condition is in the low load operating range,
Irregular changes occur in the minute valve clearance, making the fuel supply from the primary chamber to the secondary chamber unstable, or when the engine operating condition shifts from a low-load operating range to a high-load operating range, the valve may change. There is a delay in the gap widening operation, resulting in a fuel supply shortage, and as a result, a predetermined air-fuel ratio cannot be obtained in the fuel chamber.

As one measure to alleviate such inconvenience, as disclosed in Japanese Patent Application Laid-Open No. 57-168046,
The valve member that opens and closes the communication passage connecting the primary chamber and the secondary chamber has a two-stage structure, and when the operating state of the engine is in a low-load operating range, the first valve member whose diameter is small is used for the communication passage. A vaporizer configured to perform opening and closing operations using a second valve member having a large diameter communication passage in addition to the first valve member when in medium and high load operation ranges. Proposed. However, when a valve member that reduces the diameter of the communication path between the primary chamber and the secondary chamber of the vaporizer is used, the L in the primary chamber is
Tar, etc. contained in the LPG fuel as impurities, which are precipitated by the reduced pressure vaporization of the PG fuel, clog the small-diameter communication passage, making it impossible for the LPG fuel to be smoothly supplied from the primary chamber to the secondary chamber. The problem is that it is easy.

(Object of the Invention) In view of the above, the present invention provides a primary chamber for reducing the pressure of LPG fuel to a predetermined set pressure, and a primary chamber connected to the primary chamber via a communication path to supply LPG from the primary chamber. Equipped with a two-stage decompression vaporizer equipped with a secondary chamber to further depressurize the fuel,
Without making the communication passage small in diameter, it is possible to improve the stability of the LPG fuel supply amount when the engine operating state is in the low-load operating range, and when moving to the high-load operating range, the engine load It is an object of the present invention to provide a fuel supply device for an LPG engine that is capable of responsively and sufficiently supplying an amount of LPG fuel corresponding to the amount of LPG fuel.

(Structure of the Invention) A fuel supply device for an LPG engine according to the present invention includes a primary chamber that reduces the pressure of LPG fuel supplied from a fuel storage cylinder to a predetermined pressure, and a primary chamber that is connected to the primary chamber via a communication path. A two-stage pressure reducing vaporizer is provided with a secondary chamber for further reducing the pressure of LPG fuel from the primary chamber and sending it out; a detection means for detecting the operating state of the engine related to the fuel supply flow rate; The information obtained also includes an internal pressure adjusting means for adjusting the internal pressure of the primary chamber of the vaporizer, and the internal pressure adjusting means adjusts the internal pressure of the primary chamber of the vaporizer when the operating state of the engine is in a low load operating range. When it is in the high load operating range, it is operated to be lower than when it is in the high load operating range.

With this configuration, the differential pressure of LPG fuel in the primary and secondary chambers is controlled, reducing irregularities in the amount of LPG fuel supplied when the engine is in the low-load operating range and stabilizing it. In addition, when moving to a high-load operation range, the required amount of LPG can be
Fuel can be supplied with good responsiveness.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a fuel supply system for an LPG engine according to the present invention. A mixer 2 having a venturi section 2a for the purpose of

A fuel supply boat 3 is opened at the throat of the venturi section 2a, and a fuel delivery section of a vaporizer 4 is connected to this fuel supply boat 3, and the fuel is supplied from an LPG cylinder (not shown) which is a fuel storage cylinder. The LPG fuel is depressurized by the vaporizer 4 and then supplied to the fuel supply boat 3. Note that 5 is a throttle valve that is provided downstream of the venturi portion 2a of the intake passage 1 and controls the amount of intake air.

The vaporizer 4 includes a casing 6, and the inside of the casing 6 is partitioned into a first firebox 9 and a second firebox 10 by a partition wall 8 in which a hot water passage 7 is formed. These first firebox 9 and second firebox 10 are connected to a communication passage 1 that penetrates the partition wall 8.
1, and a valve seat 23a is formed on the secondary chamber lO side of the communication passage 11. In the first firebox 9, an LPG introduction port 12 connected to an LPG cylinder is formed, and this LPG i port 12 is formed.
A water valve 13 for adjusting the internal pressure of the firebox 9 by controlling the opening and closing of the water valve 13 is provided facing the valve seat 13a. 1 water valve 13 is
A primary valve lever 15 whose midway portion is pivotally supported by a support shaft 14
is supported at one end of the primary valve lever 15, and the other end of the primary valve lever 15 is
1 extending to the center of the 1 firebox 9 and between the 1 firebox 9 and the 1 Narita adjustment chamber 16 above which is set to atmospheric pressure, for example.
A U-shaped leaf spring 18 fixed to the diaphragm 17 rotates and biases the water valve 13 in the direction of closing it.

Reference numeral 19 denotes a primary pressure adjustment device, which controls the pressing force of the primary diaphragm spring 20 compressed in the 1 Narita adjustment chamber 16 against the primary diaphragm 17, as will be described later. The internal pressure of the chamber 9 is adjusted, and the opening pressure of the 1 water valve 13 is also adjusted via the primary valve lever 15.

An LPG delivery boat 21 is formed in the first and second fireboxes 10, and this LPG delivery boat 21 is connected to the fuel supply boat 3 of the mixer 2 via an LPG supply passage 22. 2
Two fireboxes 1 of the communication passage II that communicates the firebox 10 and the first firebox 9
A secondary valve 23 that controls opening and closing of the communication passage Il is disposed on the 0 side, and this secondary valve 23 is held at one end of a secondary valve lever 25 that is rotatably supported by a support shaft 24. The secondary valve 23 is designed to open and close toward or away from the valve seat 23a, and the distance between the valve seat 23a and the secondary valve 23 is defined as a valve gap. The other end of the secondary valve lever 25 extends to the center of the second firebox 10, and the other end of the secondary valve lever 25 is interposed between the lower surface of the partition wall 8 and the second end. A secondary diaphragm spring 26 is provided to rotate and bias the next valve lever 25 in the valve closing direction, and the secondary chamber l
At the center of the secondary diaphragm 28 between O and the second revision adjustment chamber 27, a support pin 29 is provided that projects upward and supports the other end of the secondary valve lever 25 from below in a receptacle state. There is.

Further, inside the second revision adjustment chamber 27, a pressure adjustment lever 31 whose one end supports a coil spring 30 that urges the secondary diaphragm 28 upward is pivotally supported by a pin 32. In the center of the other end,
A coil spring 33 is provided to bias this to rotate. Furthermore, at the tip of the other end of the pressure adjustment lever 31,
A cam 35 that can be externally operated by an adjustment screw 34 is engaged, and by rotating this cam 35 around a support shaft 36, the secondary diaphragm 28
The spring force of the coil spring 30 is adjusted to bias the secondary diaphragm 28 upward via the coil spring 30, and the opening pressure of the secondary valve 23 is adjusted via the secondary valve lever 25. A secondary pressure regulating device 37 is configured.

Furthermore, the other end of the secondary valve lever 25 is bolted to the center of a lock-off diaphragm 39 that defines the secondary chamber 10 side of a negative pressure chamber 38 that is separated from the first firebox 9 by a partition wall 8. When a high intake negative pressure acts on a negative pressure outlet port 41 provided in the intake passage 1 on the downstream side of the throttle valve 5, this intake negative pressure is transferred to the negative pressure introduction passage 42. The lock-off diaphragm 39 is introduced into the negative pressure chamber 38 through the negative pressure chamber 38 and is configured to lock-off the lock-off diaphragm 39 against the elasticity of a coil spring 43 compressed in the negative pressure chamber 38.

In this way, LPG [
After reducing the pressure of the fuel to a gas at a predetermined pressure in the first firebox 9, the pressure is reduced to approximately atmospheric pressure in the second firebox 10, L, )) G
A vaporizer 4 is configured that sends vapor from the delivery port 21 to the mixer 2 disposed in the intake passage l based on the venturi negative pressure of the mixer 2.

As described above, this vaporizer 4 is provided with the primary pressure adjustment device 19, and this primary pressure adjustment device 19 includes an adjustment screw 51 screwed into the upper part of the first Narita adjustment chamber 16,
A solenoid 52 is fixed to the upper part of the adjustment screw 51 by a connector (not shown), and the solenoid 52 projects downward while being guided through a through hole 51a formed in the adjustment screw 51, and its lower end is a primary diaphragm spring. 2
The adjustment rod 53 is fixed to the end opposite to the 001-order diaphragm 17 side. The upper end of the adjustment rod 53 is urged downward by a spring means built into the solenoid 52. Therefore, when the solenoid 52 is energized and turned on, the adjustment rod 53 is moved upward and pulls up the primary diaphragm spring 20, causing the solenoid 52 to be turned on.
When the primary diaphragm spring 20 is not energized, the spring means presses the primary diaphragm spring 20. The set load of the primary diaphragm spring 2o can be adjusted by rotating the adjusting screw 51 and moving the tip of the first adjustment rod 53 up and down.

Further, a power supply 54 for operating the solenoid 52 is arranged, and a power supply terminal 56 of the solenoid 52 is arranged opposite to a voltage supply terminal 55 connected to the power supply 54. These voltage supply terminals 55 and power supply terminals 56
can be connected to each other by a conductive member 58a connected to the lower end of the plunger rod 58 of the negative pressure response mechanism 57. Inside the negative pressure response mechanism 57,
A diaphragm 59 to which the upper end of the plunger rod 58 is fixed is arranged to form a negative pressure chamber 60, and a coil spring 61 is compressed in the negative pressure chamber 60 so as to push down the diaphragm 59. . Further, this negative pressure chamber 60 is provided with a negative pressure introduction port 63 that introduces negative pressure from a negative pressure take-off boat 41 provided in the intake passage 1 via a negative pressure introduction passage 62. Therefore, the negative pressure response mechanism 57 functions as a negative pressure switch, and the negative pressure chamber 6
When a negative pressure exceeding a predetermined value from the intake passage 1 is applied to the 0, the diaphragm 59 moves upward against the elasticity of the coil spring 61, and the plunger rod 58 moves upward accordingly. The voltage supply terminal 55 and the power supply terminal 56 are connected to the conductive member 5 as shown in the figure.
8a. On the other hand, when the negative pressure introduced into the negative pressure chamber 60 is below the predetermined value, the diaphragm 59
is pushed down by the elasticity of the coil spring 61, and the conductive member 58a is separated from the voltage supply terminal 55 and the power supply terminal 56, so that the terminals 55 and 56 are not connected.

In an example of the fuel supply system for an LPG engine according to the present invention having the above-described configuration, when the operating state of the engine is in a low load operating range, the opening degree of the throttle valve 5 is relatively small. Therefore, the negative pressure chamber 38 of the vaporizer 4 and the negative pressure chamber 60 of the negative pressure response mechanism 57 are supplied from the negative pressure outlet bow 1-41 provided on the downstream side of the throttle valve 5 through the negative pressure introduction passages 42 and 62. A relatively large negative pressure acts on the Therefore, in the negative pressure chamber 38 of the vaporizer 4, the lock-off diaphragm 39 moves upward against the elasticity of the coil spring 43, and the end of the secondary valve lever 25 opposite to the secondary valve 23 side is moved upward. is raised, and as a result, the secondary valve 23
The fully closed regulation will be lifted.

At this time, in the negative pressure chamber 60 of the negative pressure response mechanism 57, the diaphragm 59 moves upward against the elasticity of the coil spring 61 due to the negative pressure from the negative pressure take-off boat 41, and the plunger rod 58 is raised. When the negative pressure in the negative pressure chamber 6o exceeds a predetermined value, the voltage supply terminal 55 and the power supply terminal 56 are connected to each other by the conductive member 58a. As a result, the voltage from the power source 54 is applied to the solenoid 52, the solenoid 52 is energized and turned on, and the adjustment rod 53 is pulled up.
The set load of the primary diaphragm spring 2o is lowered, and the primary diaphragm 17 is moved upward. Along with this, the primary valve lever 15 rotates, and the primary valve 13 is moved to the valve seat 1.
3a and put it in the closed state. As a result, the internal space of the first firebox 9 is expanded, and due to the differential pressure between the first firebox 9 and the secondary chamber 1o, the first firebox 9 is connected to the communication passage 11, and the secondary valve 23 is
LPG fuel is supplied to the secondary chamber 1o through L-+1",
The internal pressure of the first firebox 9 decreases, and the differential pressure between the first firebox 9 and the second firebox 10 becomes smaller. Then, when the internal pressure of the first firebox 9 decreases to a certain extent, the primary diaphragm 17 moves downward, the primary valve 13 becomes open again, and the internal pressure of the first firebox 9 is adjusted by the solenoid 52 to the adjustment rod. 53 is kept constant at a reduced value compared to the state where it is not pulled up, and the differential pressure between the first firebox 9 and the second firebox 10 is also kept small.

In this way, when the operating state of the engine is in the low load operating range, the internal pressure of the first firebox 9 is reduced and the first firebox 9 and the second firebox 1
Since the differential pressure at zero is small, even if the valve gap of the secondary valve 23 is not set to be extremely small, the
The amount of LPG fuel supplied to the firebox 10 is relatively small, and the secondary valve 23, which is set to a relatively large amount, supplies a small amount of LPG fuel from the first firebox 9 to the second firebox 10. This means that it can be performed stably through the gap.

On the other hand, when the operating state of the engine shifts to a high-load operating range, the opening degree of the throttle valve 5 is set to be relatively large. The negative pressure acting on the negative pressure chamber 60 of the mechanism 57 becomes relatively small.

Therefore, the negative pressure chamber 6o of the negative pressure response mechanism 57 is in a state in which the diaphragm 59 is pushed downward from the state shown in the figure by the elasticity of the coil spring 61, and therefore the conductive member 58a is connected to the voltage supply terminal 55 and The solenoid 52 is separated from the power supply terminal 56 and is turned on without being energized. Accordingly, the adjustment rod 53 is adjusted to the solenoid 5.
The primary diaphragm 17 is caused to protrude downward by a spring means installed in the primary diaphragm 2o, thereby increasing the cent load of the primary diaphragm spring 2o and pushing the primary diaphragm 17 downward. Therefore, the internal space of the first firebox 9 returns to its original state from the expanded state, and the internal pressure of the first firebox 9 also returns from the reduced value to its original value and is kept constant. The differential pressure in chamber 10 is kept large. As a result, a relatively large amount of LPG fuel is supplied from the first firebox 9 to the second firebox 10 through the communication passage 11 and the secondary valve 23. In this way, when the operating state of the engine shifts to a high-load operating range, the internal pressure of the first firebox 9 is kept high, and the differential pressure between the first firebox 9 and the second firebox 1° is made large. Since the state is maintained, 1 through the secondary valve 23
The supply of LPG fuel from the firebox 9 to the second firebox 10 is carried out quickly and sufficiently, and the amount of LPG fuel required for increasing the engine load is 1. , PG fuel can be delivered from the second firebox 10 with good responsiveness.

FIG. 2 shows a part of another example of the fuel supply system for an LPG engine according to the present invention, and in this example, the internal pressure of one fire chamber 9 of the vaporizer 4 is continuously controlled according to the intake negative pressure. I try to do that.

In FIG. 2, parts corresponding to those shown in FIG. 1 are given the same reference numerals as in FIG. 1, and parts not shown are constructed in the same way as in FIG. 1. In this example, a plunger rod 68 of a negative pressure response mechanism 67 attached to an adjustment screw 51 by a connector (not shown) engages with the primary diaphragm spring 20 disposed in the first pyrotechnic adjustment chamber 16. diaphragm spring 20
The configuration is such that the primary diaphragm 17 is pushed by. The plunger rod 68 is loosely inserted into the through hole 51a of the adjustment screw 51 of the first pyrotechnic adjustment chamber 16, and its lower end is connected to the end of the primary diaphragm spring 20 opposite to the primary diaphragm 17 side. The upper end portion is fixed to the diaphragm 69 of the negative pressure response mechanism 67. Other configurations regarding this negative pressure response mechanism 67, ie, negative pressure chamber 70. Coil spring 71. The negative pressure introduction passage 72, the negative pressure introduction port 73, etc. are constructed in the same manner as the corresponding parts of the negative pressure response mechanism 57 shown in FIG.

In the example shown in FIG. 2, when negative pressure is introduced into the negative pressure chamber 70 from the negative pressure outlet port 41 provided in the intake passage,
In response to the negative pressure, the diaphragm 69 is pushed against the elasticity of the coil spring 71, and the set load of the primary diaphragm spring 20 is accordingly reduced, causing the primary diaphragm 17 to move upward. . As a result, the internal pressure in the primary chamber 9 of the vaporizer 4 is changed in the same manner as in the example shown in FIG. In this case, when the operating state of the engine is in a low load operating range, the negative pressure acting on the negative pressure chamber 70 becomes large, so the upward movement amount of the primary diaphragm 17 becomes large, and the vaporizer 4 The internal pressure in the primary chamber 9 of the engine is lowered accordingly, and as the operating state of the engine reaches a high negative operating range, the negative pressure chamber 7
Since the pressure acting on the primary diaphragm 17 becomes smaller, the load on the primary diaphragm spring 20 is increased, and the amount of upward movement of the primary diaphragm 17 is reduced, causing the internal pressure in the primary chamber 9 of the vaporizer 4 to decrease. It will be increased accordingly.

As a result, the same effects as in the example shown in FIG. 1 can be obtained.

In the above example, the negative pressure extraction boat 41 that extracts the intake negative pressure downstream of the throttle valve 5 in the intake passage 1 is used as a detection means for detecting the operating state of the engine related to the fuel supply flow rate. The detection means for detecting the operating state of the engine in the fuel supply system for an LPG engine according to the invention may be other means, for example, a detection means for detecting the opening degree of the throttle valve 5, and the throttle valve 5 obtained from this The primary pressure regulating device 19 may be controlled based on a signal corresponding to the opening degree of the primary pressure regulating device 19.

(Effects of the Invention) As is clear from the above description, the fuel supply device for an LPG engine according to the present invention includes a primary chamber for decompressing LPG fuel supplied from a fuel storage cylinder, and a When the internal pressure of the primary chamber of the vaporizer, which is connected via a communication path and is provided with a secondary chamber that further reduces the pressure of the LPG fuel from the primary chamber and sends it out, is in the high-load operating state of the engine. The pressure is kept high, and the pressure is kept low when in a low-load operating range, so that a corresponding differential pressure between the primary and secondary chambers can be obtained. For this reason, the primary room and the
When the diameter of the communication passage that communicates with the light chamber is made relatively large, and as a result, it is possible to avoid clogging of the communication passage with tar, etc., when the operating state of the engine is in the low-load operating range. It is possible to stably supply a relatively small amount of LPG fuel, and when moving to a high-load operation range, it is possible to supply LPG fuel in a sufficient amount in response to the amount required as the engine load increases. It can be carried out. Therefore, the air-fuel ratio can be maintained at an appropriate level over the entire operating state of the engine, from a low-load operating range to a high-load operating range.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an example of a fuel supply device for an LPG engine according to the present invention, and FIG.
FIG. 3 is a cross-sectional view showing the configuration of a portion of another example of an engine fuel supply device. In the figure, 1 is an intake passage, 4 is a vaporizer, 9 is a primary chamber,
10 is a secondary chamber, 11 is a communication passage, 17 is a primary diaphragm, 19 is a primary pressure adjustment device, 20 is a primary diaphragm spring, 41 is a negative pressure extraction boat, and 57 and 67 are negative pressure response mechanisms. Patent applicant: Toyo Kogyo Co., Ltd.

Claims (1)

[Claims] A primary chamber that reduces the pressure of LPG fuel supplied from a fuel storage cylinder, and a secondary chamber that is connected to this primary chamber via a communication passage and further reduces the pressure of LPG fuel from the primary chamber and sends it out. A two-stage depressurizing vaporizer is provided, a detection means for detecting the operating state of the engine related to the fuel supply flow rate, and an internal pressure in the primary chamber of the vaporizer is adjusted based on information obtained from the detection means. an internal pressure adjusting means, the internal pressure adjusting means is configured to lower the internal pressure in the primary chamber of the vaporizer when the operating state of the engine is in a low load operating range than when it is in a high load operating range. A fuel supply device for an LPG engine, characterized in that it operates a means for activating a fuel supply device for an LPG engine.