JPH112138A - Forklift vehicle speed control device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable high-speed outdoor driving and low-speed indoor driving as driving modes other than the cargo handling operation, and improve work efficiency. SOLUTION: At the time of a cargo handling operation in which a cargo handling lever switch 32 is turned on, a spring force of a governor spring 12 is strengthened by using a suction negative pressure on an intake manifold side via a solenoid valve 2 to increase the maximum engine speed.
When the vehicle is traveling indoors, the open state of the contact 3a is maintained by turning on the optical sensor 4, and the governor spring 12 is weakened. When running outdoors, the O
The contact 3b is turned ON by the FF, and the governor spring 12 is strengthened to enable high-speed running at the same maximum rotational speed as during cargo handling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed control device for a forklift, which limits the vehicle speed by lowering the engine speed than during cargo handling from the viewpoint of preventing accidents when the forklift is running. The present invention relates to a vehicle speed limiting device that enables a vehicle to travel at a higher speed when traveling outdoors even when traveling outdoors than when traveling indoors.

[0002]

2. Description of the Related Art For example, in the case of a gasoline engine type forklift, a pneumatic governor device provided in an engine intake system is used to prevent an accident due to excessive speed particularly when traveling indoors. The engine speed is suppressed to limit the vehicle speed (for the pneumatic governor itself, see JP-A-5-99001 and Japanese Utility Model Laid-Open No.
No. 87642).

[0003]

In the prior art as described above, the suction negative pressure on the intake manifold side is selectively introduced into the negative pressure chamber of the pneumatic governor device, and the opening of the governor valve is increased during cargo handling. In general, when the vehicle is running, the governor valve is switched to a small opening to adjust the engine speed, thereby limiting the vehicle speed while driving without reducing the cargo handling performance. The vehicle speed determined by the pneumatic governor device remains constant regardless of whether the vehicle is traveling indoors or indoors.

Since the vehicle speed determined by the pneumatic governor is set on the assumption that the vehicle is traveling indoors as described above, the vehicle travels at low speed even when traveling outdoors even when traveling indoors. In addition, the work efficiency is lowered and the operator is irritated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a structure in which a vehicle can travel at a higher speed when traveling outdoors than when traveling indoors. Is what you do.

[0006]

According to a first aspect of the present invention, there is provided a governor valve provided in an engine intake system for opening and closing an air-fuel mixture supply passage in response to a change in pressure of the engine intake system. A pneumatic governor device comprising: an urging means for energizing; and an actuator for switching the urging force of the urging means between two levels of strong and weak. In order to selectively introduce one of
A solenoid valve that operates to switch according to whether the vehicle is running or performing a cargo operation. In a vehicle speed control device of a forklift configured to limit the vehicle speed by reducing the number of revolutions, a detection unit provided in a part of a vehicle body to detect whether the vehicle itself is indoors or outdoors, Sometimes, when the detection means detects that the vehicle is outdoors, the urging force of the urging means is increased by switching the solenoid valve to the same position as during the cargo handling operation, so that the speed is higher than when traveling indoors. And a traveling mode switching means for enabling traveling in the vehicle.

[0007] For example, an optical sensor or an ultrasonic sensor is used as the above-mentioned detecting means, and whether the vehicle is outdoors or indoors depends on the roof or ceiling above the vehicle, or the presence or absence of pillars or luggage on the side of the vehicle. Is determined.

According to a second aspect of the present invention, the traveling mode switching means in the first aspect of the invention is set so that the high-speed traveling mode is always selected in a state other than the time of the cargo handling operation. Is set to be switched to the low-speed running mode when the detecting means detects that the vehicle is indoors.

According to a third aspect of the present invention, in the low speed traveling mode in the second aspect of the present invention, the accelerator switch is set to the O state.
As long as the N-operation is established and the accelerator switch is ON, the low-speed running mode is set to be maintained even if the vehicle is not detected as being indoors. The driving mode is set to be released.

According to a fourth aspect of the present invention, the driving mode switching means according to any one of the first to third aspects comprises:
It is characterized by being constituted by a keep relay interposed in the power supply circuit of the solenoid valve.

Therefore, according to the first aspect of the present invention,
When the detecting means recognizes that the vehicle itself is outdoors other than during the cargo handling operation, the traveling mode switching means switches to the high-speed traveling mode. As a result, the solenoid valve is switched to the same position as during the cargo handling operation, and the pneumatic governor device is switched so that the urging force of the urging means of the governor valve is increased, that is, the opening of the governor valve is increased. Therefore, the vehicle can travel at a high speed substantially at the same engine speed as during the cargo handling work, even in the traveling state.

According to the second aspect of the present invention, since the high-speed running mode is set to be always selected in a state other than the time of the cargo handling operation, the detecting means recognizes that the vehicle is indoors. Then, the mode is immediately switched to the low-speed traveling mode. This low-speed running mode is a conventional running mode in which the engine speed is suppressed more than during the cargo handling operation.

According to the third and fourth aspects of the present invention, the low-speed mode is established only when the accelerator switch is ON, and the traveling mode switching means has a self-holding function. And therefore,
As long as the accelerator switch is in the ON state, the low-speed running mode is maintained even if the vehicle comes out of the room, and the low-speed running mode is immediately released when the accelerator switch is turned off.

[0014]

According to the first aspect of the present invention, a low-speed traveling mode and a high-speed traveling mode are provided as modes when the vehicle is not in the cargo handling operation. When the vehicle is outdoors, the cargo handling operation is substantially performed. High-speed running at the same engine speed as at the time was possible, achieving the intended purpose of preventing accidents due to excessive speed when traveling indoors without lowering cargo handling performance, while indoors when traveling outdoors It is possible to travel at a higher speed than when traveling, and it is possible to improve the work efficiency and to suppress the annoyance of the operator, thereby further improving the safety.

According to the second aspect of the present invention, the high-speed traveling mode is set so that it is always selected except during the cargo handling operation, and when the vehicle is detected to be indoors, the mode is switched to the low-speed traveling mode. Is being replaced.
In outdoor loading and unloading work, it is possible to immediately run in the high-speed driving mode, and in indoor loading and unloading work, it is possible to immediately run in the low-speed driving mode, further improving work efficiency and safety. This has the effect of improving the performance.

According to the third aspect of the present invention, the low-speed running mode is set to be established only when the accelerator switch is ON, and the accelerator switch is turned ON.
As long as the vehicle stays indoors and outdoors, the low-speed traveling mode is maintained automatically, so that the traveling mode is not frequently switched even when the vehicle repeatedly enters and exits indoors and outdoors. There is an effect that both running performance and safety can be achieved without giving a feeling of strangeness to the vehicle.

Further, once the accelerator switch is turned off, the low-speed traveling mode is immediately released and switched to the high-speed traveling mode. Even if it becomes, if the accelerator switch is temporarily turned OFF by releasing the accelerator pedal depression force at that moment, the high-speed traveling mode can be substantially maintained,
This also has the effect of improving workability.

According to the fourth aspect of the present invention, since the traveling mode switching means is constituted by a keep relay, the traveling mode switching function can be added only by a small modification of the existing device, and the equipment cost is reduced. This has the effect of reducing

[0019]

1 to 4 show a typical embodiment of the present invention. In particular, FIG. 1 shows a specific configuration of a vehicle speed control device itself.

As shown in FIG. 1, the vehicle speed control device is roughly divided into a pneumatic governor device 1, a solenoid valve 2, a keep relay 3 functioning as running mode switching means, an optical sensor 4 serving as a detecting means, and the like. It is configured.

As is well known, the pneumatic governor device 1 is provided, for example, on the intake system of a gasoline engine, more specifically on the downstream side of a throttle valve. The governor valve 5 of the pneumatic governor device 1 has a shaft 6 And is rotatably supported via a shaft 6 in a case 8 forming a part of the intake passage 7 so as to open and close the intake passage 7.
Further, the shaft 6 protrudes into a spring accommodating portion 9 formed integrally with the case 8, and a governor cam 10 is integrally formed at a protruding end thereof. A governor spring (tensile coil spring) 12 serving as a biasing means disposed in the spring accommodating portion 9 is connected via the spring accommodating portion 9.

The other end of the governor spring 12 is connected to a diaphragm rod 14 slidably inserted into a sleeve 13, and the diaphragm rod 14 is a diaphragm chamber 17 comprising a chamber body 15 and a chamber cover 16. Is connected to the inner diaphragm 18. A diaphragm spring 20 is accommodated in a negative pressure chamber 19 defined by the diaphragm 18, and a suction negative pressure on the intake manifold side is introduced according to a switching operation of the solenoid valve 2 as described later. It has become. This allows
The diaphragm chamber 17, the diaphragm 18 and the diaphragm spring 20 form an actuator for switching the spring force of the governor spring 12 between two levels, as described later.

An adjusting handle 22 and a lock nut 23 are attached to the spring accommodating portion 9.
By rotating the adjustment handle 22, the spring force of the governor spring 12 can be finely adjusted.

The above structure is a conventionally known structure. As shown in FIG. 1, when the negative pressure is not introduced into the negative pressure chamber 19, that is, when the vehicle is running, the governor spring 12
Is weak, and the governor valve 5 is urged in the opening direction by the weak spring force. Then, the governor valve 5 opens and closes by controlling the pressure difference between the upstream and downstream of the governor valve 5, that is, the negative pressure generated downstream of the governor valve 5 in accordance with the operating state, thereby controlling the mixture supply amount. Control. More specifically, when the accelerator pedal is depressed to the maximum angle,
Since the negative pressure on the downstream side of the governor valve 5 is increased, the governor valve 5 is in a state close to a fully closed state, and further increases in the engine speed are limited.

On the other hand, when a negative pressure is introduced from the solenoid valve 2 into the negative pressure chamber 19, that is, during the cargo handling operation, the diaphragm rod 14 is moved through the diaphragm 18 in FIG.
Of the governor spring 12 is strengthened. As a result, although the governor valve 5 opens and closes in response to the negative pressure generated on the downstream side as described above,
Since the governor spring 12 biasing the governor valve 5 itself in the opening direction has a large spring force, the maximum rotational speed of the engine finally determined by the closing operation of the governor valve 5 becomes larger than that during the above-described vehicle traveling. As a result, necessary and sufficient cargo handling performance can be maintained.

The solenoid valve 2 provided on the upstream side of the diaphragm chamber 17 has an output port 24
Are connected to the negative pressure chamber 19, one input port 25 is connected to an air cleaner (not shown), and the other input port 26 is connected to an intake manifold (not shown) via a check valve 21. In a normal state where the solenoid 27 is not energized, the spool 28 is at the right offset position shown in the figure, the atmospheric pressure on the air cleaner side is introduced into the negative pressure chamber 19, and the spool 28 is moved to the left. When the position is switched to the offset position, the suction negative pressure on the intake manifold side is introduced into the negative pressure chamber 19.

The solenoid 27 of the solenoid valve 2
An ignition key switch 31 and a cargo handling lever switch 32 are provided in series in a power supply circuit 30 connecting the battery and the battery 29. In addition, the above-mentioned cargo handling lever switch 3
2 is provided independently for each operation lever such as a lift operation lever and a tilt operation lever.

The power supply circuit 30 is provided with a keep relay 3 as a running mode switching means and an optical sensor 4 as a detecting means in parallel with the cargo handling lever switch 32.
The keep relay 3 includes a contact 3a that is closed when the coil 33 is not energized, and a contact 3b that is closed instead of the contact 3a when the coil 33 is energized. Even if the ignition key switch 31 is turned on, the solenoid 27 of the solenoid valve 2 is energized via the contact 3a.

An accelerator switch 3 attached to the accelerator pedal of the vehicle in series with the contact 3b of the keep relay 3.
4 is connected, and as will be described later, when the contact 3b is once turned on by energizing the coil 33, the contact 3b is turned on under the condition that the accelerator switch 34 is turned on, that is, the accelerator pedal is depressed. Is kept ON by itself.

As shown in FIGS. 2 and 3, the optical sensor 4 is provided on a pillar 36 of a head guard for detecting whether the vehicle 35 is outdoors or indoors. For example, as shown in FIG. 2, when it is determined whether the work area is outdoors or indoors based on the presence or absence of a ceiling 37, a beam, a roof 38, or the like of the building in the work area, the work area is mounted in an upward posture as shown in FIG. In addition, as shown in FIG. 3, when discriminating between outdoor and indoor based on the presence or absence of the pillar 39 and the luggage 40 on the floor, it is mounted horizontally. In the example of FIG. 1, when the optical sensor 4 detects an obstacle such as a ceiling or a pillar and the optical sensor 4 is turned on, the terminal C shown in FIG. It is configured as follows.

According to the present embodiment configured as described above, if the ignition key switch 31 is in the ON state, when any of the cargo handling levers is operated, the cargo handling lever switch 32 is turned on. When the solenoid 27 of the valve 2 is energized, the spool 28
Is switched to the left offset position. Thus, the suction negative pressure on the intake manifold side is introduced into the negative pressure chamber 19 of the diaphragm chamber 17 as in the conventional case, and the spring force of the governor spring 12 is increased. As a result, the governor spring 12 is determined by the opening degree of the governor valve 5. The maximum engine speed is increased.

On the other hand, when the vehicle is running other than during cargo handling,
The optical sensor 4 detects whether the vehicle 35 is outdoors or indoors, and accordingly, the keep relay 3 functions as traveling mode switching means, so that traveling at an outdoor traveling speed higher than at indoor traveling time is possible. To

More specifically, unless the optical sensor 4 detects a ceiling, a pillar, or the like, the optical sensor 4 is in an OFF state, and this OFF state means that the vehicle is outdoors. When traveling outdoors, the coil 33 of the keep relay 3
Is not energized, but the contact 3 of the keep relay 3 is bypassed by the cargo handling lever switch 32 of the power supply circuit 30.
The solenoid 27 of the solenoid valve 2 is energized through a. Accordingly, a negative pressure is introduced from the solenoid valve 2 into the negative pressure chamber 19 of the diaphragm chamber 17, whereby the spring force of the governor spring 12 is increased. This state means the same state as during the cargo handling work described above,
As a result, a high-speed traveling mode is realized when traveling outdoors.

On the other hand, when the optical sensor 4 detects a ceiling, a pillar, or the like, the optical sensor 4 is turned on, and it is determined that the vehicle is indoors. When the optical sensor 4 is turned on, the terminal C in FIG. 1 is short-circuited to the terminal B as described above, so that the coil 33 of the keep relay 3 is energized.
When the coil 33 is energized, one contact 3a is turned off and the other contact 3b is turned on, so that energization of the solenoid valve 3 is blocked. As a result, FIG.
As shown in the figure, the negative pressure chamber 19 of the diaphragm chamber 17
, No negative pressure acts on it, so that the spring force of the governor spring 12 is weak. As a result, a low-speed traveling mode is realized during indoor traveling, and the engine is determined by the opening of the governor valve 5 during the indoor traveling. The maximum number of revolutions is more restricted than when traveling outdoors.

When the vehicle is traveling indoors, the coil 3
When the contact 3b is turned on by energization of the contact 3, the contact 3b itself is energized on condition that the accelerator switch 34 is on, so that the optical sensor 4 is turned off after the optical sensor 4 is once turned on. Even when the accelerator switch 34 is ON, the ON state of the contact 3b is maintained by itself, as long as the accelerator switch 34 is ON. 34, the contact 3b is immediately
The state becomes FF and the contact 3a is turned ON, so that the mode is instantaneously switched to the high-speed running mode.

FIG. 4 shows the relationship between the operating states of the above-mentioned cargo handling lever switch 32, optical sensor 4, keep relay 3, solenoid valve 2 and the like, and the operating state of the vehicle 35. When traveling indoors, the mode is switched to the low-speed traveling mode with the engine speed limited as before, but when traveling outdoors, the high-speed traveling mode with the same maximum engine speed as during cargo handling is used. Can be switched.

As is apparent from FIG.
As shown in FIG. 1, when traveling outdoors (light sensor 4 is OFF)
When the optical sensor 4 is temporarily turned on during the high-speed running mode, the coil 33 of the keep relay 3 is energized to switch to the low-speed running mode. By releasing the accelerator pedal switch 34 and turning off the accelerator pedal switch 34, the conventional high-speed traveling mode can be maintained while maintaining the ON state of the contact 3a.

Conversely, as described above, when the user goes outdoors while keeping the low-speed traveling mode while traveling indoors, the low-speed traveling mode is held as long as the accelerator pedal is kept depressed. Therefore, as shown by reference numeral P2 in FIG. 4, when the vehicle goes from indoor to outdoor, the accelerator switch 34 is momentarily turned off to switch to the high-speed running mode.

As described above, according to the present embodiment, the mode is switched to the low-speed traveling mode when traveling indoors.
When traveling outdoors, the maximum engine speed is switched to the high-speed traveling mode that is the same as during cargo handling, so that the work efficiency of the vehicle itself can be significantly improved while ensuring safety especially when traveling indoors. Become.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a typical embodiment of a vehicle speed control device of the present invention.

FIG. 2 is an explanatory side view of the forklift showing an attached state of the optical sensor.

FIG. 3 is an explanatory plan view of the forklift showing an attached state of the optical sensor.

FIG. 4 is a timing chart showing a relationship between an operation state of each component of the vehicle speed control device and a vehicle running state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pneumatic governor device 2 ... Solenoid valve 3 ... Keep relay (running mode switching means) 4 ... Optical sensor (detection means) 5 ... Governor valve 7 ... Intake passage 12 ... Governor spring (biasing means) 17 ... Diaphragm chamber (actuator) 19) Negative pressure chamber 32 ... Cargo handling lever switch 33 ... Coil 34 ... Accelerator switch

Claims (4)

[Claims] 1. A governor valve provided in an engine intake system for opening and closing an air-fuel mixture supply passage in response to a change in pressure of the engine intake system, an urging means for urging the governor valve in an opening direction, and an urging force of the urging means. A pneumatic governor device having an actuator for switching between two levels of pressure, and a vehicle for selectively introducing either atmospheric pressure or suction negative pressure as a working fluid into a negative pressure chamber of the actuator. It has a solenoid valve that switches according to whether it is running or cargo handling work.When the vehicle is running, the urging force of the biasing means is weakened compared to during loading and unloading, and the engine rotates at maximum speed. In a vehicle speed control device of a forklift that reduces the vehicle speed by reducing the number of vehicles, whether the vehicle itself is located indoors and provided in a part of the vehicle body Detection means for detecting whether the vehicle is outside; and when the detection means detects that the vehicle is outdoors when the vehicle is traveling, the solenoid valve is switched to the same position as during loading and unloading by operating the solenoid valve. A vehicle speed control device for a forklift, comprising: a driving mode switching means for increasing the urging force to enable traveling at a higher speed than when traveling indoors. 2. The traveling mode switching means is set so that the high-speed traveling mode is always selected in a state other than the time of cargo handling work, while the traveling mode switching means is set to a low speed when the detecting means detects that the vehicle is indoors. 2. The vehicle speed control device for a forklift according to claim 1, wherein the vehicle speed control device is set to switch to a traveling mode. 3. The low-speed running mode is established by an ON operation of an accelerator switch, and the accelerator switch is
As long as the vehicle is not detected as being indoors as long as the vehicle is in the N state, the low-speed running mode is set to be self-maintained, while the low-speed running mode is set to be released by turning off the accelerator switch. The vehicle speed control device for a forklift according to claim 2, wherein: 4. The forklift vehicle speed control device according to claim 1, wherein said traveling mode switching means is constituted by a keep relay interposed in a power supply circuit of a solenoid valve. .