Engine control device for industrial vehicle

Abstract

An engine control device (1) is provided with: a seat switch (18) for detecting the seated / non-seated state of a driver with respect to a driver's seat (21) of a forklift (2); a neutral switch (19) for detecting whether a direction lever (16) of the forklift (2) is at a neutral position; an engine stop control unit (22) that stops outputting of a driving force from an engine (3) when leaving of the driver from the driver's seat (21) is detected; and an engine restart control unit (23) that resumes outputting of the driving force from the engine (3) upon detection of seating of the driver on the driver's seat (21) as well as detection of the presence of the direction lever (16) at the neutral position, after the outputting of the driving force from the engine (3) has been stopped.

Description

Engine control device for industrial vehicles

[0001] The present invention relates to an engine control device for industrial vehicles.

[0002] As an engine control device for industrial vehicles, for example, the technology described in Patent Document 1 is known. The engine control device described in Patent Document 1 includes a seat switch that detects the presence or absence of a driver sitting on the driver's seat of a work vehicle, a key switch that is the main power switch of the work vehicle, and an ECU. When the ECU determines that the driver has disappeared from the driver's seat during the running of the work vehicle by the seat switch, the ECU stops the engine, and then when the key switch is turned off by the driver, the engine is set to a state where it can be started.

[0003] Japanese Patent Application Laid-Open No. 2000-318481

[0004] By the way, there is an industrial vehicle capable of performing power steering assist by operating a power steering actuator with hydraulic oil from a hydraulic pump driven by an engine. In such an industrial vehicle, when the driver once leaves the driver's seat, the engine stops until the key switch is switched from OFF to ON, so that power steering assist cannot be performed.

[0005] An object of the present invention is to provide an engine control device for an industrial vehicle that can continuously perform power steering assist even when the driver temporarily leaves the driver's seat.

[0006] One aspect of the present invention is an engine control device for an industrial vehicle in which a power steering actuator is operated by hydraulic fluid from a hydraulic pump driven by an engine, comprising: a seating / alighting detection unit for detecting whether the driver is seated or alighted from the driver's seat of the industrial vehicle; a neutral detection unit for detecting whether the direction control device of the industrial vehicle is in the neutral position; a first control unit that stops the output of driving force from the engine when the seating / alighting detection unit detects that the driver has left the driver's seat; and a second control unit that, after the first control unit has stopped the output of driving force from the engine, restarts the output of driving force from the engine when the seating / alighting detection unit detects that the driver has sat in the driver's seat and the neutral detection unit detects that the direction control device is in the neutral position.

[0007] In this type of engine control system, when the driver's departure from the driver's seat is detected, the output of driving force from the engine stops. The engine then rotates by inertia, and the engine speed gradually decreases. Subsequently, when the driver's seating is detected and the direction control is detected as being in the neutral position, the output of driving force from the engine resumes. Therefore, even if the output of driving force from the engine stops when the driver leaves the driver's seat, the output of driving force from the engine resumes when the driver sits back down in the driver's seat and moves the direction control to the neutral position before the engine rotation completely stops. As a result, the supply of hydraulic fluid from the hydraulic pump to the power steering actuator continues. This allows power steering assist to continue even when the driver temporarily leaves the driver's seat.

[0008] The engine control device further includes a fuel supply unit that supplies fuel to the engine. The first control unit controls the fuel supply unit to stop supplying fuel to the engine when the driver leaves the driver's seat, detected by the seating / alighting detection unit. The second control unit controls the fuel supply unit to restart supplying fuel to the engine when the driver is seated in the driver's seat, detected by the seating / alighting detection unit, and the direction control device is detected to be in the neutral position, detected by the neutral detection unit. In such a configuration, the output of driving force from the engine can be easily and reliably stopped or restarted by stopping or restarting the fuel supply to the engine by the fuel supply unit.

[0009] The engine control device may further include a relay positioned between the fuel supply unit and the battery. The first control unit controls the fuel supply unit via the relay to stop the fuel supply to the engine when the driver's seat departure detection unit detects that the driver has left the driver's seat. The second control unit controls the fuel supply unit via the relay to restart the fuel supply to the engine when the driver's seat departure detection unit detects that the driver is seated in the driver's seat and the direction control device is in the neutral position, and the neutral detection unit detects that the direction control device is in the neutral position. In such a configuration, if a relay that opens when current flows is used, even if the controllers constituting the first control unit and the second control unit fail, the relay will remain open and the fuel supply unit will be energized, allowing the fuel supply unit to supply fuel to the engine. In this case, engine shutdown is suppressed, allowing the industrial vehicle to be driven to a safe location.

[0010] The first control unit may stop the output of the engine's driving force when the seating / alighting detection unit detects that the driver has been away from the driver's seat for a specified period of time. In this configuration, if the driver is away from the driver's seat for only a very short time, the output of the engine's driving force will not be stopped, thus improving work efficiency.

[0011] The second control unit may issue a warning when the seating / unseating detection unit detects that the driver is seated in the driver's seat and the neutral detection unit detects that the direction control is in a position other than neutral. In this configuration, if the driver is seated in the driver's seat after the output of driving force from the engine has stopped, and the direction control is in a position other than neutral, a warning will be issued. Therefore, the driver can be notified that the state in which the output of driving force from the engine has stopped continues.

[0012] According to the present invention, power steering assist can be continuously provided even if the driver temporarily leaves the driver's seat.

[0013] This is a schematic diagram showing an industrial vehicle equipped with an engine control device according to the first embodiment of the present invention. This is a block diagram showing the configuration of the control system of the engine control device shown in Figure 1. This is a flowchart detailing the engine stop control processing procedure performed by the engine stop control unit shown in Figure 2. This is a flowchart detailing the engine restart control processing procedure performed by the engine restart control unit shown in Figure 2. This is a block diagram showing the configuration of the control system of the engine control device according to the second embodiment of the present invention. This is a flowchart detailing the engine restart control processing procedure performed by the engine restart control unit shown in Figure 5. This is a block diagram showing the configuration of the control system of the engine control device according to the third embodiment of the present invention.

[0014] Embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0015] Figure 1 is a schematic diagram showing an industrial vehicle equipped with an engine control device according to the first embodiment of the present invention. In Figure 1, the engine control device 1 of this embodiment is mounted on an engine-powered forklift 2, which is an industrial vehicle.

[0016] The forklift 2 comprises an engine 3, a transmission 5 connected to the output shaft of the engine 3 via a torque converter 4, and a pair of left and right drive wheels 8 connected to the transmission 5 via a reduction gear 6 and an axle shaft 7.

[0017] Engine 3 may be a gasoline engine or a diesel engine. Engine 3 generates driving force by burning fuel. The driving force generated by engine 3 is mechanically transmitted to the drive wheels 8 via the torque converter 4, transmission 5, reduction gear 6, and axle shaft 7, causing the drive wheels 8 to rotate. This causes the forklift 2 to move.

[0018] Furthermore, the forklift 2 includes a tank 9 for storing hydraulic fluid, a hydraulic pump 10 for discharging the hydraulic fluid stored in the tank 9, a power steering cylinder 11 (power steering actuator), a lift cylinder 12, and a tilt cylinder 13 that are operated by the hydraulic fluid discharged from the hydraulic pump 10, and a control valve unit 14.

[0019] The hydraulic pump 10 is rotationally driven by the driving force output from the engine 3. The power steering cylinder 11 is a hydraulic cylinder that provides steering assistance (hereinafter referred to as power steering assist) for the steering wheel (not shown). The lift cylinder 12 is a hydraulic cylinder that raises and lowers a pair of forks (not shown) attached to a mast (not shown). The tilt cylinder 13 is a hydraulic cylinder that tilts the mast. The control valve unit 14 controls the flow of hydraulic fluid supplied from the hydraulic pump 10 to the power steering cylinder 11, lift cylinder 12, and tilt cylinder 13.

[0020] Furthermore, the forklift 2 is equipped with a vehicle speed sensor 15 and a direction lever 16 (direction control device). The vehicle speed sensor 15 is a sensor that detects the vehicle speed of the forklift 2.

[0021] The direction lever 16 is an operating lever used to switch the transmission 5 to either forward, reverse, or neutral. When the direction lever 16 is in the neutral position, the driving force output from the engine 3 is not mechanically transmitted to the drive wheels 8 by the transmission 5. When the direction lever 16 is in the forward or reverse position, the driving force output from the engine 3 is mechanically transmitted to the drive wheels 8 by the transmission 5.

[0022] The engine control device 1 is a device that controls the engine 3. The engine control device 1 includes an injector 17, a seat switch 18, a neutral switch 19, and a vehicle control controller 20.

[0023] The injector 17 is a fuel injection valve that injects fuel into the combustion chamber (not shown) in the engine 3. The injector 17 is mounted on the cylinder head of the engine 3. The injector 17 has a control solenoid 17a to which an electrical signal from the vehicle control controller 20 is input (see Figure 2). The injector 17 constitutes a fuel supply unit that supplies fuel to the engine 3.

[0024] The seat switch 18 is a seating / standing-away detection unit that detects whether the driver (operator) is seated or standing in the driver's seat 21 of the forklift 2. Here, "standing away" means that the driver sitting in the driver's seat 21 stands up for a short time (for example, a few seconds) and moves away from the seat 21. The neutral switch 19 is a neutral detection unit that detects whether the direction lever 16 is in the neutral position.

[0025] The vehicle control controller 20 consists of a microcontroller having a CPU, RAM, ROM, and input / output interfaces. The vehicle control controller 20 receives detection signals from the vehicle speed sensor 15, seat switch 18, and neutral switch 19, performs prescribed processing, and controls the injector 17.

[0026] Figure 2 is a block diagram showing the configuration of the control system of the engine control device 1. In Figure 2, the vehicle control controller 20 has an engine stop control unit 22 and an engine restart control unit 23.

[0027] The engine stop control unit 22, when the seat switch 18 detects that the driver has left the driver's seat 21, controls the injector control solenoid 17a to stop the injection of fuel from the injector 17, thereby constituting a first control unit that stops the output of driving force from the engine 3.

[0028] The engine restart control unit 23, after the engine stop control unit 22 has stopped the output of driving force from the engine 3, and when the seat switch 18 detects that the driver is seated in the driver's seat 21 and the neutral switch 19 detects that the direction lever 16 is in the neutral position, controls the control solenoid 17a to restart fuel injection from the injector 17, thereby resuming the output of driving force from the engine 3. This constitutes a second control unit.

[0029] Figure 3 is a flowchart showing the details of the engine stop control processing procedure executed by the engine stop control unit 22.

[0030] In Figure 3, the engine stop control unit 22 first determines whether the direction lever 16 is in a position other than neutral (forward position or reverse position) based on the detection signal from the neutral switch 19 (procedure S101).

[0031] When the engine stop control unit 22 determines that the direction lever 16 is in a position other than neutral, it determines, based on the detection signal from the seat switch 18, whether the driver has been away from the driver's seat 21 for a specified period of time (procedure S102). The specified period is, for example, about 2 seconds.

[0032] When the engine stop control unit 22 determines that the driver has been away from the driver's seat 21 for a specified period of time, it controls the control solenoid 17a to close the injector 17 (procedure S103). In other words, when the engine stop control unit 22 and the seat switch 18 detect that the driver has been away from the driver's seat 21, it controls the injector 17 to stop the supply of fuel to the engine 3. At this time, the engine stop control unit 22 outputs an OFF signal as a control signal to the control solenoid 17a.

[0033] When the engine stop control unit 22 determines in step S101 that the direction lever 16 is in the neutral position, or when it determines in step S102 that the driver has not been away from the driver's seat 21 for a specified period of time, it controls the control solenoid 17a to open the injector 17 (step S104). At this time, the engine stop control unit 22 outputs an ON signal as a control signal to the control solenoid 17a.

[0034] Figure 4 is a flowchart showing the details of the engine restart control processing procedure performed by the engine restart control unit 23.

[0035] In Figure 4, the engine restart control unit 23 first determines whether the driver is seated in the driver's seat 21 based on the detection signal from the seat switch 18 (procedure S111). If the engine restart control unit 23 determines that the driver is seated in the driver's seat 21, it determines whether the direction lever 16 is in the neutral position based on the detection signal from the neutral switch 19 (procedure S112).

[0036] When the engine restart control unit 23 determines that the direction lever 16 is in the neutral position, it controls the control solenoid 17a to open the injector 17 (procedure S113). In other words, when the engine restart control unit 23 detects that the driver is seated in the driver's seat 21 via the seat switch 18 and detects that the direction lever 16 is in the neutral position via the neutral switch 19, it controls the injector 17 to restart the fuel supply to the engine 3. At this time, the engine stop control unit 22 outputs an ON signal as a control signal to the control solenoid 17a.

[0037] When the engine restart control unit 23 determines in step S111 that the driver is not seated in the driver's seat 21, or when it determines in step S112 that the direction lever 16 is not in the neutral position, it controls the control solenoid 17a to close the injector 17 (step S114). At this time, the engine stop control unit 22 outputs an OFF signal as a control signal to the control solenoid 17a.

[0038] In the above configuration, for example, if the forklift 2 is in motion with the direction lever 16 in a position other than neutral, and the driver leaves the driver's seat 21 for a specified period of time, the injector 17 will close. Consequently, the injection of fuel from the injector 17 into the engine 3 will stop, causing the engine 3 to stop and the output of driving force from the engine 3 to cease. This prevents the forklift 2 from operating unattended.

[0039] At this time, immediately after the fuel injection from the injector 17 stops, the engine 3 rotates by inertia, and the rotational speed of the engine 3 gradually decreases. As a result, the travel speed of the forklift 2 gradually decreases.

[0040] Then, before the rotation of engine 3 comes to a complete stop, that is, before the movement of forklift 2 comes to a complete stop, the driver sits in the driver's seat 21 and switches the direction lever 16 to the neutral position, causing the injector 17 to open. As a result, fuel injection from injector 17 into engine 3 resumes, the engine 3 restarts, and the output of driving force from engine 3 resumes. This allows the forklift 2 to continue moving.

[0041] As described above, in this embodiment, when it is detected that the driver has left the driver's seat 21, the output of the driving force from the engine 3 stops. Then, the engine 3 rotates by inertia, and the rotational speed of the engine 3 gradually decreases. Subsequently, when it is detected that the driver has sat back down in the driver's seat 21 and that the direction lever 16 is in the neutral position, the output of the driving force from the engine 3 resumes. Therefore, even if the output of the driving force from the engine 3 stops when the driver leaves the driver's seat 21, the output of the driving force from the engine 3 resumes when the driver sits back down in the driver's seat 21 and sets the direction lever 16 to the neutral position before the rotation of the engine 3 completely stops. As a result, the supply of hydraulic fluid from the hydraulic pump 10 to the power steering cylinder 11 continues. This makes it possible to continue power steering assist even when the driver temporarily leaves the driver's seat 21. As a result, it is possible to improve the operability of the forklift 2.

[0042] Furthermore, in this embodiment, by stopping or restarting the fuel supply to the engine 3 by the injector 17, the output of driving force from the engine 3 can be easily and reliably stopped or restarted.

[0043] Furthermore, in this embodiment, if it is detected that the driver has been away from the driver's seat 21 for a specified period of time, the output of the driving force from the engine 3 is stopped. Therefore, if the driver leaves the driver's seat 21 for a very short time, such as to readjust their position in the driver's seat 21 or to look at the cargo loaded on the forklift (described above), the output of the driving force from the engine 3 is not stopped, thus improving work efficiency.

[0044] Also, in the present embodiment, when the direction lever 16 is in the neutral position and the driving force from the engine 3 is not mechanically transmitted to the drive wheels 8, even if the departure of the driver from the driver's seat 21 is detected, the output of the driving force from the engine 3 does not stop unnecessarily.

[0045] FIG. 5 is a block diagram showing the configuration of the control system of the engine control device according to the second embodiment of the present invention. FIG. 5 is a diagram corresponding to FIG. 2. In FIG. 5, the engine control device 1 of the present embodiment includes a warning device 30 in addition to the configuration of the first embodiment described above. The warning device 30 may emit a warning sound such as a buzzer or may perform a warning display using a lamp or the like.

[0046] Further, the vehicle controller 20 of the engine control device 1 has an engine restart control unit 23A instead of the engine restart control unit 23 in the first embodiment described above.

[0047] After the engine restart control unit 23A stops the output of the driving force from the engine 3 by the engine stop control unit 22, when the seat switch 18 detects the driver's seating on the driver's seat 21 and the neutral switch 19 detects that the direction lever 16 is in the neutral position, the control solenoid 17a is controlled to resume the fuel injection from the injector 17.

[0048] Further, when the seat switch 18 detects the driver's seating on the driver's seat 21 and the neutral switch 19 detects that the direction lever 16 is in a position other than the neutral position, the engine restart control unit 23A issues a warning.

[0049] FIG. 6 is a flowchart showing the details of the engine restart control processing procedure executed by the engine restart control unit 23A. FIG. 6 is a diagram corresponding to FIG. 4.

[0050] In Figure 6, the engine restart control unit 23A executes procedures S111 to S113 sequentially, similar to the engine restart control unit 23 in the first embodiment described above. If the engine restart control unit 23A determines in procedure S112 that the direction lever 16 is not in the neutral position, it controls the warning device 30 to issue a warning (procedure S120).

[0051] When the engine restart control unit 23A determines in step S111 that the driver is not seated in the driver's seat 21, or after performing step S120, it controls the control solenoid 17a to close the injector 17 (step S114).

[0052] In this embodiment, if the direction lever 16 is in a position other than neutral when the driver sits in the driver's seat 21 after the output of driving force from the engine 3 has stopped, a warning will be issued. Therefore, the driver can be notified that the state in which the output of driving force from the engine 3 has stopped continues. In this case, the driver can restart the output of driving force from the engine 3 by switching the direction lever 16 to the neutral position.

[0053] Figure 7 is a block diagram showing the configuration of the control system of an engine control device according to a third embodiment of the present invention. Figure 7 corresponds to Figure 2. In Figure 7, the engine control device 1 of this embodiment includes a relay 41 positioned between the control solenoid 17a for the injector 17 and the battery 40 mounted on the forklift 2.

[0054] A normally closed (b) contact relay is used as relay 41, where the secondary side opens when current flows to the primary side. The open / closed state of relay 41 is switched according to a control signal from the vehicle control controller 20. Specifically, when an OFF signal is output from the vehicle control controller 20 to relay 41, relay 41 closes, and the battery 40 and the control solenoid 17a become conductive. When an ON signal is output from the vehicle control controller 20 to relay 41, relay 41 opens, and the conductivity between the battery 40 and the control solenoid 17a is interrupted.

[0055] The vehicle control controller 20 of the engine control device 1 has an engine stop control unit 22 and an engine restart control unit 23, similar to the first embodiment described above.

[0056] The engine stop control unit 22 determines that the direction lever 16 is in a position other than neutral, and that the driver has been away from the driver's seat 21 for a specified period of time, and controls the relay 41 to close the injector 17 (see steps S101 to S103 in Figure 3). In other words, when the seat switch 18 detects that the driver has left the driver's seat 21, the engine stop control unit 22 controls the injector 17 via the relay 41 to stop the supply of fuel to the engine 3.

[0057] At this time, the engine stop control unit 22 outputs an ON signal as a control signal to the relay 41. Consequently, the relay 41 opens, and the control solenoid 17a for the injector 17 goes OFF (de-energized). As a result, the injector 17 closes, and the injection of fuel from the injector 17 stops.

[0058] When the engine restart control unit 23 determines that the driver is seated in the driver's seat 21 and that the direction lever 16 is in the neutral position, it controls the relay 41 to open the injector 17 (see steps S111 to S113 in Figure 4). In other words, when the seat switch 18 detects that the driver is seated in the driver's seat 21 and the neutral switch 19 detects that the direction lever 16 is in the neutral position, the engine restart control unit 23 controls the injector 17 via the relay 41 to restart the fuel supply to the engine 3.

[0059] At this time, the engine restart control unit 23 outputs an OFF signal as a control signal to the relay 41. Consequently, the relay 41 is closed (state shown in Figure 7), and the solenoid 17a for controlling the injector 17 is turned ON (energized). As a result, the injector 17 opens, and fuel injection from the injector 17 resumes.

[0060] Thus, in this embodiment, even if the vehicle control controller 20 malfunctions, the relay 41 remains open, and the control solenoid 17a for the injector 17 becomes energized, making it possible to supply fuel to the engine 3 by the injector 17. In this case, the engine 3 is prevented from stopping, allowing the forklift 2 to move to a safe location.

[0061] It should be noted that the present invention is not limited to the above embodiments. For example, in the above embodiment, when the driver leaves the driver's seat 21 while the forklift 2 is in motion, the output of the driving force from the engine 3 is stopped. However, even when the forklift 2 is stopped, if the driver leaves the driver's seat 21, the output of the driving force from the engine 3 is stopped.

[0062] Furthermore, in the above embodiment, the injector 17 is controlled to close when it is detected that the driver has been away from the driver's seat 21 for a specified period of time. However, the system is not limited to this configuration, and the injector 17 may be controlled to close at the moment it is detected that the driver has been away from the driver's seat 21.

[0063] Furthermore, in the above embodiment, the injector 17 is controlled to close when it is detected that the driver has been away from the driver's seat 21 for a specified period of time while the direction lever 16 is in a position other than neutral. However, the system is not limited to this configuration, and the injector 17 may be controlled to close even when the direction lever 16 is in the neutral position if it is detected that the driver has been away from the driver's seat 21.

[0064] Furthermore, in the above embodiment, the output of the driving force from the engine 3 is stopped or restarted by controlling the injector 17, but the embodiment is not particularly limited to this. For example, the output of the driving force from the engine 3 may be stopped or restarted by controlling the spark plug that ignites the fuel-air mixture in the engine 3, or by controlling the throttle valve that adjusts the amount of intake air to the engine 3.

[0065] Furthermore, although the engine control device 1 in the above embodiment is mounted on a forklift 2, the present invention can also be applied to industrial vehicles such as towing tractors, as long as they are equipped with a power steering actuator.

[0066] 1 Engine control unit 2 Forklift (industrial vehicle) 3 Engine 10 Hydraulic pump 11 Power steering cylinder (power steering actuator) 16 Direction lever (direction control device) 17 Injector (fuel supply unit) 18 Seat switch (seat / remove detection unit) 19 Neutral switch (neutral detection unit) 21 Driver's seat 22 Engine stop control unit (first control unit) 23, 23A Engine restart control unit (second control unit) 30 Warning device 40 Battery 41 Relay

Claims

1. An engine control device for an industrial vehicle in which a power steering actuator is operated by hydraulic oil from a hydraulic pump driven by the engine, comprising: a seat-absence detection unit that detects whether a driver is seated in or out of the driver's seat of the industrial vehicle; a neutral detection unit that detects whether a direction operating device of the industrial vehicle is in the neutral position; a first control unit that stops the output of driving force from the engine when the seat-absence detection unit detects that the driver has left the driver's seat; and a second control unit that resumes the output of driving force from the engine after the first control unit has stopped the output of driving force from the engine when the seat-absence detection unit detects that the driver is seated in the driver's seat and the neutral detection unit detects that the direction operating device is in the neutral position.

2. An engine control device for an industrial vehicle as described in claim 1, further comprising a fuel supply unit that supplies fuel to the engine, wherein the first control unit controls the fuel supply unit to stop the supply of fuel to the engine when the seating / leaving detection unit detects that the driver has left the driver's seat, and the second control unit controls the fuel supply unit to resume the supply of fuel to the engine when the seating / leaving detection unit detects that the driver is seated in the driver's seat and the neutral detection unit detects that the direction operating device is in the neutral position.

3. An engine control device for an industrial vehicle as described in claim 2, further comprising a relay arranged between the fuel supply unit and a battery, wherein the first control unit controls the fuel supply unit via the relay to stop the supply of fuel to the engine when the seating / leaving detection unit detects that the driver has left the driver's seat, and the second control unit controls the fuel supply unit via the relay to resume the supply of fuel to the engine when the seating / leaving detection unit detects that the driver is seated in the driver's seat and the neutral detection unit detects that the direction operating device is in the neutral position.

4. An engine control device for an industrial vehicle as described in any one of claims 1 to 3, wherein the first control unit stops the output of driving force from the engine when the seating / leaving detection unit detects that the driver has been away from the driver's seat for a specified period of time.

5. An engine control device for an industrial vehicle as described in any one of claims 1 to 4, wherein the second control unit issues a warning when the seating / leaving detection unit detects that the driver is seated in the driver's seat and the neutral detection unit detects that the direction operating device is in a position other than neutral.