JPH0849580A - Engine stall preventing device - Google Patents

Abstract

PURPOSE:To provide a high-pressure washer avoiding to be enlarged and preventing an engine stall due to an overload without using a clutch having many troubles as an engine stall preventing countermeasure. CONSTITUTION:A detecting circuit 66 detects the revolving speed of a small two-cycle engine based on the number of pulses generated by a primary ignition coil 16, it turns on a transistor 68 at the engine revolving speed or below that an engine stall is anticipated, and a solenoid opening/closing valve 64 is excited to open a connecting passage 60. When the connecting passage 60 is opened, the intake pipe 52 and discharge pipe 54 of a reciprocating pump 30 are communicated with each other, and the reciprocating pump 30 has nearly no load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing stall of an engine installed in a high pressure washer, a power sprayer or the like.

[0002]

2. Description of the Related Art In a high pressure washer and a power sprayer, an engine is operated at a relatively low speed. In addition, the engine may be directly connected to the pump without a reduction gear,
In that case, the inertial mass of the engine rotation is small. Therefore, engine stall is likely to occur due to temporary overload or deceleration. Due to changes in weather conditions such as an increase in temperature and humidity, the engine output decreases, and the load on the engine increases correspondingly, engine stalls easily occur, and such weather conditions continue for a long time, When the air cleaner is splashed with water, once the engine stall occurs, it becomes difficult to restart the engine thereafter, and it is desired to avoid the engine stall.

The conventional measures for preventing engine stall in a high-pressure washing machine or the like are as follows. (A) Use an engine with high output. (B) With a speed reducer interposed between the engine and the pump,
Increases the inertial mass of engine rotation. (C) A clutch is interposed between the engine and the pump to disengage the clutch to reduce the engine load.

[0004]

The adoption of an engine with a large output and the interposition of a speed reducer and a clutch are disadvantageous because they lead to an increase in the size and cost of the entire apparatus such as a washing machine. Further, controlling the engine load by engaging / disengaging the clutch increases the number of times of engaging / disengaging the clutch and shortens the life of the clutch when the engine is repeatedly overloaded and allowed. Further, when the clutch is disengaged, the pump operation is completely stopped, and although it is inferior to the normal time, it is impossible to prevent the engine stall while ensuring a predetermined amount of pump operation.

In order to prevent engine stall, an object of the invention is to prevent engine stall due to overload without using a clutch that has many obstacles and avoiding increase in size, while preventing engine stall. Is to provide. An object of the inventions of claims 2 and 4 is to provide an engine stall prevention device capable of appropriately detecting a sign of engine stall. An object of the inventions of claims 3 and 4 is to provide an engine stall prevention device capable of appropriately controlling the load of the pump in the application to a high pressure washer or a power sprayer. A further object of the invention of claim 4 is to be able to secure the electric power necessary for operating the engine stall prevention device without adding a dedicated generator. An object of the invention of claim 5 is to provide an engine stall prevention device that can suppress a decrease in the operating capacity of a pump for avoiding engine stall to a minimum.

[0006]

The present invention will be described using reference numerals in the drawings corresponding to the embodiments. The engine stall prevention device according to claim 1 has the following components (a) and (b). (A) Engine stall predictor detecting means (66, 66) for detecting a stall sign of the engine (13) that drives the driven device (30).
(86,88) (b) When the engine stall precursor detection means (66,86,88) detects the precursor of the engine stall, the driven device (30)
Load reduction means (64,78,80)

According to a second aspect of the present invention, there is provided the engine stall prevention apparatus according to the first aspect, wherein the engine stall precursor detection means (66,86,88) has a predetermined engine stall indication and an engine rotation speed. It is detected because it is less than the value.

According to a third aspect of the present invention, there is provided the engine stall prevention device according to the first or second aspect, wherein the load reducing means (64, 78, 80) is a driven device (3).
The discharge port (42) of the pump (30) as 0) is opened to the low pressure part (52) to reduce the load of the pump (30).

The engine stall prevention device according to claim 4 has the following components (a) to (f). (A) A rotor (1 that rotates in synchronization with the rotation of the engine (13)
2) Permanent magnet attached to (2) (b) Primary ignition coil (16) in which ignition primary current is induced by change in distance from the permanent magnet (14) (c) Engine (13) due to interruption of ignition primary current Secondary ignition coil induced ignition secondary current for spark plug (20)
(18) (d) Power storage means (26) that stores the electric power by being charged with the ignition primary current of the non-interrupted polarity (e) Low pressure from the discharge port (42) of the pump (30) driven by the engine (13) Discharge flow rate control means (64, 78, 80) for controlling the fluid discharge flow rate to the section (52) (f) Detecting the engine rotation speed of the engine (13) from the number of generated pulses of the primary ignition coil (16) When the engine speed is below a predetermined value, the discharge flow rate control means from the power storage means (26)
(64,78,80) control the power supply to (64,78,80)
Power supply control means (6, 80) to increase the fluid discharge flow rate (6
6,86,88)

According to a fifth aspect of the engine stall prevention device of the present invention, in the engine stall prevention device of the fourth aspect, the discharge flow rate control means (78, 80) can switch the fluid discharge flow rate to a plurality of stages. The power supply control means (66, 86, 88) sets the fluid discharge flow rate in the discharge flow rate control means (78, 80) to the first fluid discharge flow rate at a speed equal to or lower than the first engine rotation speed, Below the low second engine speed, the second fluid discharge flow rate is smaller than the first fluid discharge flow rate.

[0011]

According to the engine stall prevention device of the first aspect, the engine stall precursor detection means (66, 86, 88) detects the precursor of engine stall. The load reducing means (64, 78, 80) reduces the load on the driven device (30) when the engine stall indication detecting means (66, 86, 88) detects the sign of engine stall. This reduces the engine load and
In the case of (13), the reduction of the rotation speed is suppressed and the stall is avoided.

In the engine stall prevention device of the second aspect, when the engine stall is likely to occur, the engine rotation speed continuously decreases and finally becomes the predetermined value or less. The engine stall indication detecting means (66, 86, 88) detects engine stall because the engine rotation speed has become equal to or lower than a predetermined value.

In the engine stall prevention device of the third aspect, the load reducing means (64, 78, 80) causes the discharge port (42) of the pump (30) to have a low pressure portion (52) when a sign of engine stall is recognized. ) To. As a result, the load on the pump (30) is reduced, the engine load is also reduced, and the engine (13) is prevented from decreasing in rotation speed and stall is avoided.

According to another aspect of the engine stall prevention device of the present invention, the distance between the primary ignition coil (16) and the permanent magnet (14) is increased or decreased in accordance with the rotation of the rotor (12), and the primary ignition coil (16) is AC and pulsed. Ignition primary current is induced. Power supply control means (66,
86, 88) detects the engine rotation speed from the ignition primary current pulse, and the ignition primary current is cut off when it has a predetermined polarity,
The secondary ignition coil (18) is induced with high-voltage ignition secondary current,
The spark plug (20) is supplied with the ignition secondary current and ignites the fuel in the combustion chamber of the engine (13). The ignition primary current is stored in the power storage means (26) when the polarity is one that is not interrupted due to the generation of the ignition secondary current in the secondary ignition coil (18). When there is a sign of engine stall, the engine speed falls below a predetermined value and the power supply control means (66,86,8
8) switches the connection between the power storage means (26) and the discharge flow rate control means (64, 78, 80) when the engine speed becomes equal to or lower than this predetermined value. As a result, the discharge flow rate control means (64, 78, 80) opens the discharge port (42) of the pump (30) to the low pressure part (52), and the pump (3
The load of 0) is reduced.

According to another aspect of the engine stall prevention device of the present invention, when the engine speed is equal to or lower than the first engine speed, the discharge flow rate control means (78, 80) is operated from the discharge port (42) of the pump (30). And the fluid discharge flow rate of is the first predetermined flow rate. As a result, the load on the pump (30) is reduced by the first load amount. When the engine rotation speed is equal to or lower than the second engine rotation speed, the discharge flow rate control means (78, 80) changes the fluid discharge flow rate from the discharge port (42) of the pump (30) to the second fluid discharge flow rate (> The first fluid discharge flow rate). This allows
The load of the pump (30) is reduced by the second load amount (> the first load amount).

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a detailed view of a portion of the engine stall prevention device of the high pressure washer 10. The flywheel 12 is integrally attached to a crankshaft (not shown) of a small two-cycle engine 13 (only reference numeral) in the rotational direction, and a permanent magnet 14 is embedded at one position in the circumferential direction. The primary ignition coil 16 and the secondary ignition coil 18 are wound around a common magnetic core, and an alternating primary ignition current is generated in the primary ignition coil 16 due to the approach and separation of the permanent magnet 14 accompanying the rotation of the flywheel 12. It The spark plug 20 is mounted on the small two-cycle engine 13 and ignites the fuel in the combustion chamber of the small two-cycle engine 13 by the secondary ignition current from the secondary ignition coil 18. The engine stop switch 22 forms one closed loop together with the primary ignition coil 16 and is manually operated. When it is turned on, both ends of the primary ignition coil 16 are short-circuited to stop the generation of the ignition primary current, and the small secondary switch 22 is provided. The operation of the cycle engine 13 is forcibly stopped. The ignition primary current interruption circuit 24 interrupts the ignition primary current in the primary ignition coil 16 and generates an ignition secondary current in the secondary ignition coil 18 in synchronization with the rotation of the flywheel 12.

The capacitor 26 and the diode 28 form a closed loop together with the primary ignition coil 16 so that the ignition primary current having a polarity opposite to that of the ignition primary current interrupted by the ignition primary current interruption circuit 24 passes through the diode 28. Then, the capacitor 26 is charged.

The reciprocating pump 30 is a small two-cycle engine.
The crankshaft 32 is directly connected to the crankshaft 13 and the rotation of the crankshaft 32 is converted by the connecting rod 34 into the reciprocating motion of a reciprocating member 36 such as a piston or a plunger. pump room
38, the volume is increased or decreased with the reciprocating motion of the reciprocating member 36,
Suction valve 44 and discharge valve 46 to suction port 40 and discharge port 42, respectively
Through the. The tank 48 stores water 50, and the suction pipe line 52 guides the water 50 in the tank 48 to the suction port 40. Discharge pipeline
54 guides the water 50 from the discharge port 42 to the nozzle 56 (only reference numeral).

The residual liquid passage 58 and the connection passage 60 mutually connect the suction conduit 52 and the discharge conduit 54, and the pressure regulating valve 62 is connected to the residual liquid passage 58.
Is disposed in the recirculation pump 30 to control the flow cross-sectional area of the residual liquid passage 58 and adjust the discharge pressure of the reciprocating pump 30 to a desired value. The electromagnetic opening / closing valve 64 opens / closes the connection passage 60.

The detection circuit 66 is supplied with the voltage across the primary ignition coil 16, and determines the rotational speed of the flywheel 12 from the number of ignition primary current pulses per unit time, that is, a small two-cycle engine driving the reciprocating pump 30. Detect the rotation speed of 13. The transistor 68 is controlled to be turned on / off by the detection circuit 66. When the transistor 68 is turned on, the capacitor 26 is connected to the electromagnetic opening / closing valve 64 to energize the electromagnetic opening / closing valve 64.

The operation of the engine stall prevention device of FIG. 1 will be described. Small two-cycle engine during washing work
13 is operated, and the reciprocating pump 30 is driven by the small two-cycle engine 13 to discharge the water 50 in the tank 48 sucked through the suction pipe line 52 to the discharge pipe line 54. The primary ignition coil 16 includes a permanent magnet 14 associated with the rotation of the flywheel 12.
Ignition primary current is induced by increasing or decreasing the distance to, the ignition primary current interruption circuit 24 interrupts the ignition primary current in synchronization with the rotation of the flywheel 12, and the secondary ignition coil 18 has a high ignition secondary current. Induces an electric current. In this way, the induced secondary ignition current is supplied to the spark plug 20 to ignite the air-fuel mixture in the combustion chamber of the small two-cycle engine 13. The ignition primary current passes through the diode 28 when the polarity of the permanent magnet 14 is opposite to that of the permanent magnet 14 approaching the primary ignition coil 16 and when the permanent magnet 14 is separated from the primary ignition coil 16. The capacitor 26 is charged and a predetermined electric power is stored in the capacitor 26.

In a normal operating condition, the rotation speed of the small two-cycle engine 13 is, for example, 4000 r.p.m. p. m. And the detection circuit 66 keeps the transistor 68 off. As a result, the electromagnetic opening / closing valve 64 closes the connection passage 60, and the hydraulic pressure in the discharge conduit 54 is held at the value adjusted by the pressure adjusting valve 62.

Due to the decrease in the output of the small two-cycle engine 13 due to the increase in temperature and humidity and the temporary increase in the load of the reciprocating pump 30, the rotation speed of the small two-cycle engine 13 is reduced, for example, 3000 rpm. p. m. The following may occur. If left as it is, engine stall normally occurs, but the detection circuit 66 indicates that the engine speed is 30
00r. p. m. When it detects that: transistor 68 is switched on. This allows the capacitor
Power is supplied from 26 to the solenoid on-off valve 64
Is energized to open the connection passage 60. As a result, the water 50 in the discharge conduit 54 is returned to the suction conduit 52 via the connection conduit 60 having a sufficiently large cross-sectional area for recirculation to the pump chamber 38 and the hydraulic pressure in the discharge conduit 54. Is reduced to almost atmospheric pressure, and the reciprocating pump 30 is in an almost unloaded state. With this, the load of the small two-cycle engine 13 is reduced,
The small two-cycle engine 13 is prevented from further decreasing its rotation speed, or is reversed or increased to avoid engine stall.

Even when the flow passage cross-sectional area of the connection passage 60 is appropriately narrowed and the connection passage 60 is open, the hydraulic pressure in the discharge pipe 54 is lower than the normal pressure, but is higher than the atmospheric pressure. Therefore, the nozzle 56
It is possible to continue the spout of water 50 from.

FIG. 2 is a block diagram of a device for preventing engine stall by suppressing the load reduction amount of the reciprocating pump 30 to the minimum. Illustration of parts common to FIG. 1 is omitted, and only main points are illustrated. First connection passage 70 and second connection passage 72
Are arranged in parallel with each other, and are connected to the suction conduit 52 and the discharge conduit 54 at both ends similarly to the connecting passage 60 of FIG. 1, and the first connecting passage 70 has a flow cross-sectional area defined by an orifice 74. ing. The first electromagnetic on-off valve 78 and the second electromagnetic on-off valve 80 are controlled in energization state by the power supply current from the capacitor 26 by the first transistor 82 and the second transistor 84, respectively. The opening / closing of the second connection passage 72 is controlled. First detection circuit 86 and second
Similarly to the detection circuit 66 of FIG. 1, the detection circuit 88 of FIG. 1 detects the rotation speed of the small two-cycle engine 13 from the number of ignition primary current pulses at both ends of the primary ignition coil 16, and outputs, for example, 3000 r. p. m. Below and 2500 r. p.
m. Hereinafter, the first transistor 82 and the second transistor 84 are turned on.

The operation of the engine stall prevention device of FIG. 2 will be described. When the small two-cycle engine 13 is operated under a normal load, the engine speed is, for example, 4000 rpm. p. m. The first detection circuit 86 and the second detection circuit 88 turn off the first transistor 82 and the second transistor 84, and the first electromagnetic opening / closing valve 78 and the second electromagnetic opening / closing valve 80 are the first Connection passage 70 and second connection passage 72
Is closed. Therefore, the discharge pressure of the reciprocating pump 30 is maintained at a value adjusted by the pressure adjusting valve 62, and the nozzle 56 ejects the water 50 at a normal ejection pressure.

The output of the small two-cycle engine 13 decreases due to an increase in temperature and humidity, and the engine load for the output of the small two-cycle engine 13 increases correspondingly. The small two-cycle engine 13 becomes overloaded and reduces the engine rotation speed. The engine speed is 3000r. p. m. When the following occurs, the first detection circuit 86 turns on the first transistor 82, and the first electromagnetic opening / closing valve 78 opens the first connection passage 70. Thus, the discharge line
A part of the water 50 in 54 is returned to the suction conduit 52 via the orifice 74, the water pressure in the discharge conduit 54 is reduced, and the load on the reciprocating pump 30 is reduced. This enables the compact two-cycle engine 13
The load of is also reduced by that amount, and further reduction of the engine rotation speed is suppressed, and the occurrence of engine stall is suppressed. Further, the orifice 74 maintains a liquid pressure appropriately higher than the atmospheric pressure in the discharge pipe 54, and the jetting of the water 50 from the nozzle 56 is inferior to the normal time, but is ensured to be performed.

When the engine speed further decreases, 2
500r. p. m. In the following cases, the second detection circuit 88 turns on the second transistor 84 to turn on the second electromagnetic opening / closing valve.
80 opens the second connecting passage 72. The second connecting passage 72 has a sufficiently large flow cross-sectional area, and when the second connecting passage 72 is opened, the water pressure in the discharge pipe 54 is reduced to almost the water pressure in the suction pipe 52, which causes the reciprocating pump. 30 is almost unloaded. In this way, the small two-cycle engine 13 is also put into a substantially no-load state, so that further reduction of the rotation speed is suppressed and the engine stall is prevented. In addition,
As in the case of the connection passage 60 of FIG. 1, the flow cross-sectional area of the second connection passage 72 is appropriately reduced so that the hydraulic pressure of the discharge pipe 54 is normally maintained even when the second connection passage 72 is open. The jetting of the water 50 from the nozzle 56 can be continued by setting the pressure to be a value higher than the atmospheric pressure but lower than the time.

Although the small two-cycle engine 13 is described in the embodiment, the present invention is also applicable to a four-cycle engine. Although the embodiment describes the high pressure washer 10, the engine stall prevention device of the present invention is also applicable to a power sprayer or the like for spraying a chemical solution or the like to a field. In the embodiment, the solenoid opening / closing valve 64, the first solenoid opening / closing valve 78, and the second solenoid opening / closing valve 80 are adapted to open when energized. However, if sufficient electric power can be stored in the capacitor 26, It may be closed when energized and opened when de-energized. In the embodiment, the reciprocating pump 30 sucks and discharges the water 50, but a fluid other than the water 50 may be sucked and discharged.

[0030]

According to the first and fourth aspects of the present invention, the load on the driven device or pump driven by the engine is reduced to prevent engine stall. Therefore, in order to prevent engine stall, an engine with a large output and a speed reducer to increase the inertial mass of the engine rotation are adopted to prevent the overall size of the device from becoming large. Can be shortened, or the use of a clutch that can only stop the operation of the driven device when engine stall is prevented can be omitted.

In the second and fourth aspects of the invention, when the engine stall occurs, the engine speed continuously decreases and finally becomes equal to or lower than the predetermined value. Can be properly detected because the value is less than or equal to the predetermined value.

According to the third and fourth aspects of the invention, in the application to the high pressure washing machine or the power spraying machine, the load of the pump can be reduced by connecting the discharge port of the pump to the low pressure part.

According to the invention of claim 4, the ignition primary current having a polarity opposite to the polarity of the ignition primary current which is cut off for generating the ignition secondary current in the secondary ignition coil is stored in the storage means. Then, since it is used for energizing the discharge flow rate control means, the addition of a dedicated generator can be omitted.

According to the fifth aspect of the present invention, the pump is controlled so that the reduction amount of the load of the pump increases as the possibility of engine stall increases, so that the ability of the pump to reduce the engine stall is reduced. Can be minimized.

[Brief description of drawings]

FIG. 1 is a detailed view of a portion of an engine stall prevention device of a high pressure washer.

FIG. 2 is a configuration diagram of a device that prevents an engine stall by suppressing a load reduction amount of a reciprocating pump to a minimum.

[Explanation of symbols]

12 Flywheel (Rotor) 13 Small Two-Cycle Engine 14 Permanent Magnet 16 Primary Ignition Coil 18 Secondary Ignition Coil 20 Spark Plug 26 Capacitor (Power Storage Means) 30 Reciprocating Pump (Pump, Driven Device) 42 Discharge Port 52 Intake Pipeline ( Low pressure part) 64 Electromagnetic on-off valve (load reducing means, opening valve, discharge flow rate controlling means) 66 Detection circuit (engine stall sign detecting means, power supply controlling means) 78 First electromagnetic opening / closing valve (load reducing means, opening valve, discharging) Flow rate control means) 80 Second electromagnetic on-off valve (load reduction means, release valve, discharge flow rate control means) 86 First detection circuit (engine stall indication detection means, power supply control means) 88 Second detection circuit (engine stall) Sign detection means, power supply control means)

Claims (5)

[Claims] 1. An engine stall predictor detecting means (66,86,88) for detecting a stall sign of an engine (13) for driving a driven device (30), and (b) the engine stall sign detection. When a sign of engine stall is detected by the means (66, 86, 88), load reducing means (64, 78, 80) for reducing the load on the driven device (30), Engine stall prevention device. 2. The engine stall sign detection means (66,
The engine stall prevention device according to claim 1, characterized in that the engine stall (86, 88) detects a sign of engine stall when the engine rotational speed is below a predetermined value. 3. The load reducing means (64, 78, 80) comprises a discharge port (42) of a pump (30) as the driven device (30) at a low pressure part.
The engine stall prevention device according to claim 1 or 2, wherein the pump (30) is opened to reduce the load on the pump (30). 4. (a) Permanent magnets (14), (b) attached to a rotor (12) that rotates in synchronization with the rotation of the engine (13).
Primary ignition coil (16) in which an ignition primary current is induced by a change in distance from the permanent magnet (14), (c) Ignition secondary for the ignition plug (20) of the engine (13) by interruption of the ignition primary current A secondary ignition coil (18) that induces an electric current, (d) a storage means (26) that stores an electric power by being charged with an ignition primary current of the polarity that is not cut off, (e) driven by the engine (13) Discharge flow rate control means (64, 78, 80) for controlling the fluid discharge flow rate from the discharge port (42) of the pump (30) to the low pressure part (52), (f)
When the engine rotation speed of the engine (13) is detected from the number of generated pulses of the primary ignition coil (16) and the engine rotation speed is equal to or lower than a predetermined value, the discharge flow rate control means (64, 78, 80) to control the power supply to the discharge flow rate control means (64, 78, 80) to increase the fluid discharge flow rate (66, 86, 88), characterized in that it has a Engine stall prevention device. 5. The discharge flow rate control means (78, 80) is capable of switching the fluid discharge flow rate in a plurality of stages, and the power supply control means (6
6,86,88) sets the fluid discharge flow rate in the discharge flow rate control means (78,80) as a first fluid discharge flow rate at a speed equal to or lower than the first engine rotation speed, and a second flow speed smaller than the first engine rotation speed. 5. The engine stall prevention device according to claim 4, wherein the second fluid discharge flow rate is smaller than the first fluid discharge flow rate at a speed equal to or lower than the engine rotation speed.