JPH048278Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical Field of the Invention] This invention relates to an engine control device used in a tractor equipped with a vehicle height adjustment function, such as an electronically controlled air suspension. [Technical background of the invention] Generally, a semi-tractor as shown in FIG. 2 is used as a power vehicle for pulling a trailer for transporting cargo. Recently, semi-tractors have been equipped with a vehicle height adjustment function called electronically controlled air suspension. This electronically controlled air suspension includes, for example, an axle 11 and a chassis frame 1.
A telescopic air tank 13 interposed between the
In this case, the vehicle height of the tractor is raised by supplying compressed air to the air tank 13, and the compressed air in the air tank 13 is increased or decreased. The vehicle height is controlled to be lowered by discharging the fuel. This electronically controlled air suspension is normally used to keep the vehicle height of the tractor constant at all times, but on the other hand, the dashed lines a and b
As shown in the figure, the vehicle height at the rear of the tractor can be controlled to be raised or lowered as appropriate by means of a main switch for adjusting vehicle height in the driver's seat (not shown).
That is, as shown in FIG. 3A, for example, when moving the installation position of the trailer 14 in a port yard, compressed air is supplied to the air tank 13 of the air suspension to raise the vehicle height at the rear of the tractor. The trailer 14 can be moved without operating the landing gear 15. Furthermore, as shown in FIG. 3B, when connecting or disconnecting the trailer 14, the compressed air in the air tank 13 is discharged to lower the vehicle height at the rear of the tractor.
Its workability has been improved. [Problems with the Background Art] However, in a tractor equipped with an air suspension as described above, if the rear vehicle height is controlled to be significantly raised or lowered, for example, the vehicle will not be able to travel, especially at speeds above the medium speed range. Since the speed becomes unstable, it is necessary to limit the running speed. Furthermore, as shown in FIG. 3A above,
When controlling the rear vehicle height of the tractor to increase when the trailer 14 is connected, please note that the safety standards of the Road Traffic Act prohibit high-speed driving of vehicles with a vehicle height limit h exceeding 3.8 m. There must be. [Purpose of the invention] This invention was created in view of the above-mentioned problems. For example, when adjusting the vehicle height when connecting, moving, or disconnecting a trailer, the engine cannot reach a speed higher than a certain speed. The purpose is to provide a control device. [Summary of the invention] That is, the engine control device according to this invention includes a main switch for vehicle height adjustment that is turned on when the rear vehicle height of the tractor is moved up and down by the vehicle height adjustment function, and a set gear position of the transmission. and a compressed air flow control valve that is turned on when the vehicle height adjustment main switch is turned on and the gear position detection means detects a gear position other than a low gear position or a reverse gear position. , and an air cylinder that limits the engine governor within a predetermined operating range by compressed air supplied through the control valve when the control valve is turned on, and when the gear position is not in either a low gear or a reverse gear. The engine speed is limited to a low rotation speed. [Embodiment of the invention] An embodiment of the invention will be described below with reference to the drawings. FIG. 1 shows its configuration, and this engine control device is installed in a semi-tractor equipped with a vehicle height adjustment mechanism 21 such as an electronically controlled air suspension. This vehicle height adjustment mechanism 21 has a vehicle height adjustment main switch 22 that is turned on when, for example, the rear vehicle height of the tractor is varied up or down, and this main switch 22 displays an indication that the vehicle height adjustment is in progress. Pilot lamps 23 are connected in series. In addition, the main switch 22 for adjusting the vehicle height
For example, a gear stage detection sensor 25 provided on the gear shift unit 24 is connected in series. This gear position detection sensor 25 is provided in parallel with a reverse switch REV that closes the circuit when the reverse gear is set and a first speed switch 1ST that closes the circuit when the first forward gear is set.
5 is further connected in series with an electromagnetic relay coil 26.
Connect L. Movable contact 2 of this electromagnetic relay 26
The main switch 22 for adjusting the vehicle height is connected to 6S, and the solenoid valve 27 for compressed air circulation is connected to the fixed contact a. This solenoid valve 27 allows the compressed air supplied from the air tank 28 to flow from x to y when it is on, and discharges the compressed air sent to the y side when it is off, to the outside. An air pipe on the y side from the solenoid valve 27 is connected to an air cylinder 30 provided within the engine system 29. When the air cylinder 30 is at its maximum extension, the operating range of the engine governor 31 that controls engine rotation is limited to a predetermined stroke.
The operating range is, for example, the range until the engine speed reaches a maximum of 600 revolutions. Here, the air cylinder 30 expands and contracts in response to the supply and discharge of compressed air. That is, in the engine control device configured in this way, for example, as shown in FIG.
When connecting, moving, and disconnecting the trailer 14 in the port yard, when the main switch 22 for height adjustment is turned on to vertically change the rear vehicle height of the tractor using the vehicle height adjustment mechanism 21, the pilot lamp 23 turns on. Light. Here, if either the reverse switch REV or the first speed switch 1ST of the gear position detection sensor 25 is closed, the electromagnetic relay coil 26L is energized and its movable contact 26S is switched to the fixed contact B side. . In this case, the solenoid valve 27 is not energized, so the compressed air in the air cylinder 30 remains discharged.
The operating range of engine governor 31 is not limited.
As a result, even when the vehicle height adjustment mechanism 21 is in operation, if the gear position is set to reverse or first gear, it is possible to drive without being restricted by the engine speed. Here, since the maximum speed during the reverse or first speed setting is extremely low, even if the vehicle height of the tractor is set at a high position, the running state of the tractor will not become unstable. On the other hand, when the vehicle height adjustment main switch 22 is turned on, if both the reverse switch REV and the first speed switch 1ST of the gear position detection sensor 25 are open, that is, the tractor gear is set to reverse or forward. When the gear position is set to a medium speed or high speed other than first speed, the electromagnetic relay coil 26L is not energized, so the movable contact 26S is switched to the fixed contact a side. In this case, the electromagnetic valve 27 is energized, compressed air from the air tank 28 is supplied to the air cylinder 30 in the engine system 29, and the piston position becomes the most extended state. As a result, the engine governor 31 is restricted to a predetermined operating range, and the engine speed can be suppressed to, for example, 600 rotations or less.
That is, while the vehicle height adjustment mechanism 21 is in operation,
If the tractor gear is set to medium or high speed, it is virtually impossible to drive at that medium or high speed, and if the vehicle height is set to a high or low position, Unstable running can be prevented. Here, the relationship between the set gear position and the engine speed when the vehicle height adjustment main switch 22 is turned on and off is shown below.

[Table] The engine control device described above is configured so that the solenoid valve 27 is turned off during normal driving so that compressed air is not required, so it is highly reliable and durable. . [Effects of the invention] As described above, according to this invention, when the main switch for adjusting vehicle height is turned on and the gear position detection sensor detects first gear or any other gear position other than reverse, the engine speed is Since the ascent limit is suppressed to a low rotational speed, for example, when adjusting the vehicle height when moving the trailer installation position, only low speed travel can be performed, and high safety can be ensured. In addition, when the gear position detection sensor detects first gear or reverse gear, the above-mentioned engine rotational speed increase restriction is lifted, so in this case, sufficient starting performance of the vehicle is ensured. Become.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an engine control device according to an embodiment of this invention, Fig. 2 is a diagram showing a vehicle height adjustment function of a semi-tractor, and Figs. 3 A and B respectively show the state of movement of a trailer by a tractor and FIG. 3 is a diagram showing a disconnected state. 21... Vehicle height adjustment mechanism, 22... Main switch for vehicle height adjustment, 25... Gear stage detection sensor, 26
... Solenoid relay, 27 ... Solenoid valve for compressed air distribution, 30 ... Air cylinder, 31 ... Engine governor.

Claims (1)

[Scope of Claim for Utility Model Registration] An engine control device for a tractor equipped with a vehicle height adjustment function, which is installed in the driver's cab and uses the vehicle height adjustment function to adjust the rear vehicle height of the tractor from its normal position when towing a trailer. A main switch for adjusting the vehicle height that is turned on when moving the vehicle up and down, a movable contact of an electromagnetic relay connected in series to the main switch, and a movable contact of an electromagnetic relay connected in series to the movable contact to supply compressed air from the air tank to the air cylinder. A compressed air distribution control valve controls the supply, and when the main switch is turned on, the compressed air distribution control valve is operated via a movable contact of the electromagnetic relay, and the engine rotation is caused by the expansion operation of the air cylinder. an engine governor that limits the number of gears within a predetermined range, a gear position detection sensor that detects whether the transmission is in first gear or reverse gear, and a gear position detection sensor that detects whether the transmission is in first gear or reverse gear; and an electromagnetic relay coil that switches a movable contact of an electromagnetic relay to a cut-off side, and when the transmission is in first gear or reverse gear, the electromagnetic relay coil switches the movable contact to a cut-off side so that the engine An engine control device characterized in that the engine control device is configured to cancel the engine rotation speed restriction of a governor.