JPH0386610A - Control for ground clearance lowering indication lamp for height control system - Google Patents

Abstract

PURPOSE:To improve safety by prohibiting the turn ON of a ground clearance lowering indication lamp during traveling and operating the ground clearance lowering indication lamp when the state where the pressure in the piston upper chamber of a hydraulic cylinder is over a prescribed value continues for a prescribed time, in a height control system for a truck, etc. CONSTITUTION:Each signal of a down switch 35, up switch 36, car speed sensor 39, parking brake sensor 40, detection switches 37 and 38 for the hydraulic pressure in the piston upper chamber of a hydraulic cylinder 1, and an engine revolution speed sensor 41 is inputted into the controller 34 of a control means 3, and the ground clearance adjustment is carried out. At this time, the controller 34 does not turn ON a ground clearance lowering indication lamp 42 independently of the signals of the pressure switches 37 and 38 during traveling, and when each detection pressure of the pressure switches 37 and 38 becomes over a prescribed value and this state continues for a prescribed time, the ground clearance lowering indication lamp 42 is flashed or turned ON. With this constitution, safety can be improved.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling a lamp in a vehicle height adjustment device configured to adjust the vehicle height between a normal height and a predetermined lowered position and to turn on the lamp in a lowered vehicle height state.

[Conventional technology]

For example, in the case of a truck with a loading platform at the rear of the vehicle,
Since the height of the cargo bed is generally relatively high, it is not so easy to load and unload heavy cargo, and this is especially true for large vehicles. For this reason, there are also low deck type trucks that have smaller tires to lower the height of the loading platform. However, in the case of such an automobile, since the ground clearance is low, problems arise such as the possibility that the vehicle may come into contact with an office worker when driving on an uneven road.

[Problem to be solved by the invention]

Therefore, the above problem can be solved by providing a vehicle height adjustment device that can raise and lower the loading platform so that the height of the loading platform can be lowered when necessary, and the height of the loading platform can be returned to the normal height during driving. The specific configuration of the vehicle height adjustment device is that it is interposed between the vehicle body (loading platform) and an unsprung member at the rear of the vehicle, the lower end of the cylinder is connected to the unsprung member, and the upper end of the piston rond is connected to the vehicle body. , a hydraulic cylinder connected to each other, a hydraulic pump connected to the hydraulic cylinder and capable of feeding oil into the piston upper chamber of the cylinder or suctioning oil from the piston upper chamber, and a normal height position and a predetermined lowered position. It is conceivable to provide a control means constituted by a microcomputer or the like, which controls a hydraulic pump so that the height of the loading platform can be adjusted between the two. In this vehicle height adjustment device, the loading platform is lowered by sending oil into the piston upper chamber of the hydraulic cylinder. When oil is sent into the upper chamber of the piston,
The piston and the piston rond are pushed down by the hydraulic pressure in the piston upper chamber, and at this time, the hydraulic cylinder compresses and deforms the suspension spring and lowers the vehicle body, moving the piston rond downward, so the height of the cargo platform can be lowered. can be lowered. On the other hand, when oil is sucked from the piston upper chamber of the hydraulic cylinder, the pressure in the piston upper chamber decreases, and the piston rond and the vehicle body are moved upward while receiving the elastic restoring force of the suspension spring, and the loading platform is usually raised to a height. Back to Sa. In addition, when controlling the vehicle height adjustment device,
A vehicle height sensor is required, but a typical sensor that detects the vehicle height by measuring the amount of elastic compression of the Sitec absorber or the amount of vertical displacement of the suspension arm is a large-scale device. Therefore, as a method of easily constructing a vehicle height sensor by conveniently utilizing the mechanism of the vehicle height adjustment device, there is a method of providing a pressure sensor that detects the pressure inside the piston upper chamber. When the loading platform is at a predetermined lowered position, the pressure in the piston upper chamber is greater than or equal to a predetermined upper limit, while when the loading platform is at a normal height, the pressure in the piston upper chamber is less than or equal to a predetermined lower limit. By detecting the pressure inside the piston upper chamber, it is possible to substantially detect the vehicle height. By the way, in such a vehicle height adjustment device, in order to improve safety, it is desirable to provide a vehicle height lowering indicator lamp that lights up when the loading platform is lowered.When the loading platform is lowered, the suspension spring is compressed and becomes an almost rigid body. If you continue to drive in this state, the running stability will deteriorate significantly, and there is a risk of damage to the vehicle as the non-vibration impact will be transmitted directly to the vehicle body, so do not move the loading platform. It is necessary to avoid driving with the vehicle height lowered, so a vehicle height lowering indicator lamp is installed.
This is because if this light is turned on when the cargo platform is lowered, the UA will always be aware that the vehicle height is lowered, and the user can be alerted to return the vehicle height to the normal height before starting the vehicle. Furthermore, if an abnormality occurs in the device and the loading platform starts to lower itself while the vehicle is running, there is an advantage that the user can be notified of the malfunction of the device by lighting the lamp. Further, the lighting control of this vehicle height lowering indicator lamp can be performed using the above-mentioned pressure sensor.The signal from the pressure sensor indicates that the pressure in the piston upper chamber of the hydraulic cylinder is equal to or higher than a predetermined upper limit value. In other words, the lamp may be turned on when the signal indicates that the loading platform is in a lowered state. However, in controlling the lighting of the lamp in this manner, it has been found that although the control can be performed easily, the following problems occur. Since the hydraulic cylinder is interposed between the vehicle body and the unsprung member, when the vehicle body vibrates up and down while the vehicle is running, its piston rod is moved up and down. however,
When the vehicle body vibrates intensely, such as when driving on a rough road with steep bumps, the vertical movement of the piston rod also increases, and the pressure inside the hydraulic cylinder momentarily rises above the upper limit threshold that turns on the lamp. Sometimes I do. In this case, the pressure sensor reacts and the vehicle height lowering indicator lamp lights up accordingly.However, when driving, the lamps turn on one by one even though no device is operating. This confuses the driver and has a negative impact on driving. Therefore, while driving, regardless of the signal from the pressure sensor,
The above problem can be solved by not lighting the lamp. However, in such a case, another problem arises. In other words, even if the loading platform lowers itself while the vehicle is in motion due to a malfunction in the device, the lamp will not light up.
A situation may occur where the user does not notice the abnormality at all.
If the loading platform begins to lower while driving, it is necessary to refrain from driving any further for safety reasons. The present invention was devised under the above circumstances, and is capable of adjusting the vehicle height between the normal height and a predetermined lowered position, and lights up a lamp in the vehicle height lowered state. With the vehicle height adjustment system configured as shown above, it is possible to prevent the inconvenience of the lamps being turned on incorrectly when driving on rough roads, etc., and also to prevent the vehicle height from lowering automatically when the device is malfunctioning while driving. It is an object of the present invention to provide a 1111111 method for a vehicle height lowering indicator lamp configured to detect an abnormality and notify a user of the occurrence of an abnormal situation. [! Means for Solving Ill] In order to solve the above problems, the present invention takes the following technical measures. That is, the present invention provides a hydraulic cylinder interposed between a vehicle body and an unsprung member, the lower end of which is connected to the unsprung member, and the upper end of a piston rond to the vehicle body; a hydraulic pump connected to the piston upper chamber of the cylinder to send oil into the piston upper chamber or suck oil from the piston upper chamber to move the piston rod up and down; a pressure sensor that detects the pressure in the piston upper chamber; a control means for controlling the hydraulic pump to determine a vehicle height state based on information from the pressure sensor and to adjust the vehicle height between a normal height and a predetermined lowering position; In a vehicle height adjustment device equipped with a vehicle height lowering indicator lamp that flashes or lights up,
While driving, the vehicle height lowering indicator lamp is not turned on, and when the pressure in the piston upper chamber of the hydraulic cylinder becomes higher than a predetermined value while driving, the pressure in the piston upper chamber is detected after a predetermined period of time has elapsed. The present invention is characterized in that the vehicle height reduction indicator lamp is flashed or lit if the pressure in the piston upper chamber is still higher than the predetermined value when the pressure reduction is performed again later or continuously until a predetermined time period has elapsed.

[Operation and effects of the invention]

The hydraulic cylinder interposed between the vehicle body and the unsprung member is
The lower end of the cylinder is connected to the unsprung member, and the upper end of the piston rod is connected to the vehicle body. Therefore, when oil is sent from the hydraulic pump into the piston upper chamber of the hydraulic cylinder and the piston rond is pushed down by the hydraulic pressure in the piston upper chamber, the piston rond compresses and deforms the suspension spring and moves downward while pulling down the vehicle body. As a result, the vehicle height is lowered. - direction,
Oil is sucked from the upper chamber of the piston of the hydraulic cylinder,
When the pressure in the piston upper chamber decreases, the piston rod and the vehicle body are moved upward while receiving the elastic restoring force of the suspension spring, and the vehicle height returns to the normal state. Further, in such vehicle height adjustment, the control means determines the vehicle height state based on information from a pressure sensor that detects the pressure in the piston upper chamber of the hydraulic cylinder, and adjusts the device to 111 m. When the vehicle height is lowered, the pressure inside the piston upper chamber exceeds a predetermined upper limit, and if the vehicle height is at the normal height, the pressure inside the piston upper chamber drops below the predetermined lower limit, so the pressure inside the hydraulic cylinder increases. By detecting the pressure, the vehicle height condition can be recognized. Incidentally, when the vehicle height is lowered, a lamp flashes or is turned on, thereby reminding the driver not to start driving with the vehicle height lowered. This is because when the vehicle height is lowered, the suspension springs are compressed and hardly perform their original function as suspension springs, and if the vehicle is driven in such a condition, driving stability will be extremely poor. . Then, the lamp is controlled using the pressure sensor, and when the pressure inside the piston upper chamber of the hydraulic cylinder exceeds the predetermined upper limit value, in other words, the vehicle height reaches a predetermined lowering position. However, in the present invention, this vehicle height lowering indicator lamp is not turned on as a general rule while the vehicle is being driven. Therefore, when driving on rough roads, etc., the piston rod of the hydraulic cylinder interposed between the vehicle body and the unsprung member moves up and down violently due to vibrations of the vehicle body, and the pressure inside the hydraulic cylinder momentarily increases above Even when the vehicle height is higher than the predetermined upper limit threshold, the vehicle height lowering indicator lamp does not light up. However, when the pressure inside the hydraulic cylinder exceeds a predetermined value while driving, a fail detection is performed, and it is determined whether the pressure increase inside the hydraulic cylinder is simply temporary due to body vibration, or whether there is an abnormality. It will be determined whether this is due to the device operating on its own and the loading platform actually starting to lower. Specifically, when the pressure in the hydraulic cylinder becomes higher than the predetermined lower limit threshold indicating that the vehicle height is in the normal state, or exceeds the predetermined upper limit threshold, Detecting the pressure in the hydraulic cylinder again after a predetermined period of time or continuously until the predetermined period of time has elapsed;
If the pressure in the hydraulic cylinder is still higher than a predetermined value after a predetermined period of time has elapsed, a vehicle height reduction indicator lamp is made to blink or turn on. This is because if the pressure in the hydraulic cylinder is still higher than the predetermined value even after the predetermined time has elapsed, it can be considered that the vehicle height is being lowered. therefore,
If an abnormal situation occurs while driving, the user can be informed by the lighting of the lamp, and can promptly take measures such as stopping the car immediately. As described above, in the present invention, it is possible to prevent the vehicle height lowering indicator lamp from being erroneously lit when driving on a rough road, etc., so that the driver is not confused, and the vehicle height does not lower due to a malfunction of the device while driving. If something happens, the abnormality can be detected and a lamp will be lit to notify you of this, increasing safety.

[Explanation of Examples]

Embodiments of the present invention will be specifically described below with reference to the drawings. This example shows an example in which the present invention is applied to a vehicle height adjustment device configured as a cargo platform height adjustment device for a trunk car. The loading platform height adjustment device is provided below the loading platform at the rear of the vehicle. As shown in FIGS. 5, 6, and 9, this system includes a hydraulic cylinder 1 interposed between the vehicle body and the unsprung member, and a hydraulic pump 2 that drives this hydraulic cylinder 1. , a control means 3 for controlling the drive of the hydraulic pump 2, and a vehicle height lowering indicator lamp 42 that is turned on when the loading platform is lowered. In the case of this example, the hydraulic cylinder l is configured using the shock absorber of the rear suspension, and as described later, it functions as the original shock absorber during normal times, and when adjusting the vehicle height, it functions as the shock absorber of the rear suspension. function as an actuator to raise and lower. As shown in FIG. 7, the sink absorber in this example is of a twin tube type, and includes a cylinder 5 whose lower end is connected to an unsprung member such as an axle tube 4, and a cylinder 5 which is connected at its lower end to an unsprung member such as an axle tube 4. A piston rod 8 which has a slidably disposed piston 6 at its lower end and whose upper end protrudes from the upper part of the cylinder is connected to, for example, a vehicle body frame, and an outer shell which surrounds the cylinder 5 and forms a reservoir chamber 9. A tube 10 is provided. Piston upper chamber 11 and piston lower chamber 1 in the cylinder 5
2 are communicated with each other via a passage 13 provided at the lower end of the piston 6 or the piston rod 8, and the oil is communicated with the passage 13, the lower end of the piston rod 8, and a shaft formed in the piston 6. The piston upper chamber 11 passes through the direction hole 14 and the orifice 44 at the lower end of the piston.
and the piston lower chamber 12. Furthermore, in the case of this example, the piston 6 is provided with a check valve 15 that only allows oil to flow from the piston lower chamber 12 to the piston upper chamber 11. Furthermore, a base valve portion 16 is provided at the lower end of the cylinder 5 to partition the lower piston chamber 12 and the reservoir chamber 9. This base valve part 1
6 is provided with an orifice 17 and a check valve 18 that only allows oil to flow from the reservoir chamber 9 to the lower piston chamber 12, as shown in FIG. Therefore, in the extension stroke in which the piston rod 8 moves upward, the piston In the contraction stroke in which the rod 8 moves downward, a damping force is generated due to the flow resistance when oil flows from the piston lower chamber 12 through the orifice 17 to the reservoir chamber 9. Further, in the case of this example, both the left and right suspension absorbers are used as the hydraulic cylinder I. On the other hand, the hydraulic pump 2 uses a motor 19 that drives the pump and an oil tank 20 that are integrated, and is attached to a cross member 21 that extends in the vehicle width direction between the left and right frames. There is. The hydraulic pump 2 sends oil to the hydraulic cylinder l, which is originally a shock absorber, and transfers the oil to the vehicle body (
As shown in FIGS. 5, 6 and 9, the left and right hydraulic cylinders 1. are connected to each other. When the hydraulic pump 2 is driven in the normal direction, oil is sucked up from the oil tank 20 through the oil passage 27 into the piston upper chamber 11 of the hydraulic cylinder 1, and when the hydraulic pump 2 is driven in the reverse direction, it is sucked from the piston upper chamber 11 side. Oil is drained into oil tank 20 via passage 28. Further, the motor 19 that drives the pump is connected to an alternator or battery,
It is powered by these sources and operated. The connection between the hydraulic cylinder 1 and the hose 22 is to connect the hose 22 to an oil port 22 provided at the upper end of the piston rod 8.
This is done by connecting to. Further, the piston rod 8 has an upper end connected to the oil bow 123,
An oil hole 24 is formed whose lower end extends in the axial direction following the axial hole 14 formed at the lower end of the piston rod. In this example, as shown in FIGS. 7 and 8, a pilot is provided at the bottom of the oil hole 24 to cut off communication between the piston upper chamber II and the piston lower chamber 12 when the hydraulic pressure supplied from the hydraulic pump 2 is generated. A valve 25 is incorporated. This pyro valve 25 has a valve body 26 that is slidably inserted into the oil hole 24 and urged upward by a compression coil spring 43. When the valve body 26 is moved downward against the spring force by the extraction pressure supplied from the hydraulic pump 2, it cuts off communication between the piston upper chamber 11 and the piston lower chamber 12, and also connects the oil hole 24 and the piston upper chamber. 11 to allow the hydraulic cylinder l to function as an actuator. That is, when oil is sent from the hydraulic pump 2 through the hose 22 into the oil hole 24 of the piston rod 8, the oil pressure causes the valve body 26 to move downward from the passage 13 as shown by the imaginary line in FIG. Being pushed down. This results in
The passage 13 is substantially closed, the piston upper chamber 11 and the piston lower chamber 12 are in a non-communicating state, and the oil sent from the hydraulic pump 2 is transferred to the oil hole 24 and the oil hole 24.
a gap between the inner periphery of the valve body 26 and the small-diameter Rondo portion 26a of the valve body 26;
and flows only into the piston upper chamber ll through the passage 13. Therefore, at this time, the piston 6 and the piston rod 8 are forcibly pushed down by the hydraulic pressure in the piston upper chamber 11, so that the loading platform can be pulled down and its height can be lowered. A hydraulic cylinder l, which is interposed between the vehicle body and the unsprung member and whose upper end portion of the piston rod 8 is connected to the vehicle body (loading platform) side, applies pressure m to the suspension spring 32 in the vertical direction.
This is because the piston rod 8 is moved downward while deforming and lowering the vehicle body (loading platform). On the other hand, the hydraulic pump 2 is driven in reverse and the piston upper chamber l
When the oil in l is returned to the oil tank 20 side, the piston rod 8 and the loading platform are moved upward while receiving the elastic restoring force of the suspension spring 32 that has been compressed and deformed. Therefore, the height of the loading platform returns to the normal height. Also,
At this time, due to the pressure drop in the oil hole 24 of the piston rod 8, the valve body 26 of the pilot valve 25 is returned to the passage unblocked position as shown by the solid line in FIGS. Since the chamber 11 and the piston lower chamber 12 communicate with each other via the passage 13, the hydraulic cylinder 1 can function as an original shock absorber. Note that the oil passage connecting the hydraulic pump 2 and the hydraulic cylinder 1 (
As shown in FIG. 9, an operating check valve 29 is provided on the hose 22), which is connected to the oil line 28 through a pilot line 30 when oil is discharged from the hydraulic pump 2 to the oil tank 20. It is being The operating check valve 29 allows oil to be sent to the hydraulic cylinder 1 side when the hydraulic pump 2 is driven in normal rotation,
It also functions as a check valve to prevent backflow of oil when the hydraulic pump 2 is driven in normal rotation and when stopped. Therefore, after sending oil into the piston upper chamber ll and moving the piston rod 8 downward to lower the loading platform, the hydraulic pump 2
Even when the piston is stopped, the hydraulic pressure capable of maintaining the height of the loading platform against the spring force of the suspension spring 32 can be maintained in the piston upper chamber ll. On the other hand, when the hydraulic pump 2 is driven in reverse and oil is discharged from the hydraulic pump 2 to the oil tank 20 via the oil passage 28, the oil pressure in the oil passage 28 is due to the influence of the throttle 31 provided on the oil passage 28. rises, and the oil pressure acts as a pilot pressure to open the operating check valve 29 via the biloft pipe 30. Therefore, when the hydraulic pump 2 is driven in reverse, oil can be sucked from inside the piston upper chamber 11 of the hydraulic cylinder 1 and discharged into the oil tank 20. In addition, since it is generally difficult to achieve a perfect seal between the piston 6 and the cylinder 5, the pressure in the piston upper chamber 11 increases when oil is fed into the piston upper chamber 11 by the hydraulic pump 2. If there is a significant increase in
In the event that oil may leak from the piston upper chamber 11 to the piston lower chamber 12,
A problem arises in that the internal pressure of the hydraulic cylinder 1, which is a shock absorber, in its natural state fluctuates. Therefore,
In this example, when oil leaks from the piston upper chamber 11 to the piston lower chamber I2, a return hose 3 is used to recover the oil from the reservoir chamber 9 to the oil tank 20.
3 is provided between the hydraulic cylinder 1 and the oil tank 20, so that the above problem can be prevented from occurring. Further, the hydraulic pump 2 is controlled by a control means 3,
Thereby, the vehicle height adjustment mode in which the hydraulic cylinder 1 functions as an actuator and the shock absorber mode in which the hydraulic cylinder 1 functions as a vibration damping device can be appropriately selected. In this example, the control means 3 includes a controller 34 constituted by a microcomputer or the like, and the controller 34 includes an operation switch for changing the mode,
Signals from various sensors are input as control information. The controller 34 also controls the motor 1 of the hydraulic pump 2.
It is connected to a drive circuit 9 (not shown), and controls the drive of the motor 19 or the hydraulic pump 2 based on the above control information. As shown in FIG. 9, there are two types of operation switches, a down switch 35 and an up switch 36, which are mounted, for example, on a continuous section of an instrument panel in the driver's cab. When the down switch 35 is turned on, the motor 19 and the hydraulic pump 2 are driven to rotate in the normal direction, thereby lowering the cargo platform. On the other hand, the amplifier switch 36
When the hydraulic pump 2 is turned on, the hydraulic pump 2 can be driven in reverse to return the loading platform to its normal height. Further, the above-mentioned sensor is provided with the following. One of them is a pressure sensor that detects the pressure inside the piston upper chamber 11 of the hydraulic cylinder 1 and essentially functions as a vehicle height sensor.In this example, this sensor uses a pressure switch. A high-pressure side pressure switch 31 and a low-pressure side pressure cusp inch 38 are provided. As shown in FIG. 6, these are attached to the hydraulic pump 2 and detect the oil pressure in the oil passage 22 between the hydraulic pump 2 and the hydraulic cylinder 1 or in the piston upper chamber 11 of the hydraulic cylinder 1. The signals from these pressure switches 37, 38 are used to determine whether the loading platform is in the lowered position or the normal height position. When the loading platform is at a predetermined lowered position, the pressure in the piston upper chamber 11, into which oil is fed from the hydraulic pump 2, exceeds a predetermined upper limit threshold, and when the loading platform is at the normal height position, Since the pressure in the piston upper chamber 11 is below the predetermined lower limit threshold, the vehicle height condition can be known by detecting the pressure in the piston upper chamber 11. When the pressure in the chamber 1 exceeds the upper limit threshold, in other words, when the loading platform reaches the lowered position, the old Gl+ (No. 8 is sent to the controller 34 from the high pressure side pressure switch 37). , when the pressure in the piston upper chamber 11 becomes below the lower limit threshold value, in other words, when the loading platform is returned to the normal height, the LOII signal is sent from the low-pressure side pressure chamber 38 to the controller 34. Then, the controller 34 determines the vehicle height state based on the signals from the pressure switches 37 and 38, and controls the driving of the motor 19 or the hydraulic pump 2. Vehicle speed sensor 39 and parking brake sensor 40 for detecting the situation
A signal from the engine rotation speed detection sensor 41 is also sent. This allows the cargo bed to be lowered only when the parking brake is applied, the vehicle is stopped, and the engine is running, and the cargo bed can only be lowered when the vehicle starts driving with the cargo bed in the lowered position. A system is configured that forcibly returns the loading platform to its normal height regardless of whether or not the amplifier switch 36 is operated. When operating the hydraulic pump 2 with the engine turned off, it relies solely on the battery as its power source, but in this case,
This is because there is a risk that the battery will be exhausted and the battery will run out. In addition, when the loading platform is lowered,
As mentioned above, the suspension spring 32 is compressed and becomes almost a rigid body, so if the suspension spring 32 is compressed and the vehicle is driven in that state, vibrations or shocks during driving will be directly transmitted to the vehicle body, significantly impairing driving stability. In addition, there is a risk of damage to the vehicle. Therefore, when the vehicle is traveling, the loading platform is reliably returned to its normal height to prevent the above-mentioned problem from occurring. Further, the control means 3 turns on the vehicle height lowering indicator lamp 42, which is provided at a conspicuous location such as the front surface of the instrument panel, when the cargo platform is lowered. This control is performed using the pressure switches 37 and 38, and is performed when the pressure in the piston upper chamber 11 of the hydraulic cylinder l exceeds the predetermined upper limit threshold, or when the pressure exceeds the predetermined lower limit threshold. When the height is higher than the value, that is, when the loading platform is lowered to a predetermined lowering position or while the loading platform is being lowered, the vehicle height lowering indicator lamp 42 is turned on. In addition, in the case of the present invention, the pressure switch 3 is
Regardless of the signal from 7.38, in principle, the vehicle height lowering indicator lamp 42 is not turned on. This is to prevent the vehicle height reduction indicator lamp 42 from being turned on due to a temporary pressure increase due to the vertical movement of the piston rod 8 due to vibrations of the vehicle body when driving on a rough road. However, when the pressure inside the hydraulic cylinder 1 becomes higher than a predetermined value while the vehicle is running, foil detection is performed.
It is determined whether the above-mentioned rise in pressure is simply due to vehicle body vibration or is due to an abnormality in the device causing the loading platform to start lowering. When an abnormal situation occurs, the vehicle height lowering indicator lamp 42 is blinked or turned on to notify the user of the abnormality. In addition, the fail detection is performed by detecting the pressure inside the hydraulic cylinder 1 again after a predetermined period of time has elapsed, or continuously until the predetermined period of time has elapsed. Alternatively, if it is higher than the lower limit threshold, the vehicle height lowering indicator lamp 42 is turned on. This is because if the pressure inside the hydraulic cylinder 1 is still higher than the predetermined value even after a predetermined time has elapsed, it is considered that the loading platform is lowered. Next, the operation of this loading platform height adjustment device with the above configuration is as follows.
This will be explained with reference to the flowcharts shown in FIGS. 1 to 4. Note that these flowcharts are subroutine flowcharts included in the main flowchart. First, the loading platform lowering operation system will be explained based on the flowchart of FIG. The loading platform is lowered by turning on the down switch 35. In this case, the above pressure switch 37.38
Based on the signal from
And if the height is not being adjusted (3201, 5202
and No in 3203), and further, based on the signals from the parking brake sensor 40, engine speed detection sensor 41, and vehicle speed sensor 39, it is determined whether the loading platform lowering condition is satisfied. Here, if the vehicle is stopped with the parking brake applied and the engine is running (S 204.5
205 and 3206), that is, if the motor 19 and hydraulic pump 2 are operated without worrying about increasing the battery life, and if there is no risk of the car starting to move unexpectedly while adjusting the vehicle height, then the above-mentioned down switch 35
By this operation, the motor 19 and the hydraulic pump 2 are driven, thereby operating the hydraulic cylinder 1, and the loading platform can be lowered to a predetermined position (S211). However, in the case of this example, the switch-on of the down switch 35 is configured to be recognized when the controller 34 detects a change from an off signal to an on signal of the switch. This is because the controller receives a LOW signal when the switch is on, and a LOW signal when the switch is off.
+ signals are respectively sent, and generally the controller is configured to determine whether to turn the switch on or off depending on the type of the input signal. However, with this configuration, if the harness that connects the switch and the controller is short-circuited for some reason while the vehicle is running, the following problem will occur. That is, the down switch 35 described above
If a short-circuit failure occurs, the L (IW) signal continues to be input to the controller, regardless of whether the down switch 35 is on or off. Since the structure is such that the loading platform can only be lowered when certain conditions are met, even if the down switch 35 is short-circuited, the loading platform will not start lowering while driving, but it will not start lowering when waiting at a traffic light. When the parking brake is pulled, the loading platform lowering condition is met and the loading platform will start lowering automatically. Therefore, if a configuration is made so that the loading platform will not be lowered unless a change in the input signal is detected. , the above-mentioned inconveniences can be prevented. Even if the shortening failure of the switch occurs while the vehicle is running and the load platform lowering condition is corrected when the vehicle is stopped, the input signal from the down switch 35 remains the LO signal, and the input signal is This is because if there is no change in the signal, the controller 34 will not recognize that the switch has been turned on.In this example, the above control is performed by detecting the rise of the down switch 35 as follows. This will be explained based on the flowchart of Fig. 2 and its subroutine flowchart (see Fig. 3).As shown in Fig. 3, when the down switch 35 is not turned on, (YES in 5301), the off flag of the down switch 35 is set (3302)
. When the down switch 35 is turned on from such a state (S 301: YES), it is determined whether the off flag of the down switch 35 is set, and if the off flag is set (S 303). DeY
ES), a rising flag of the down switch 35 is set, indicating that there has been a change in the input signal (S304
). Then, as shown in FIG. 2, the down switch 35
When the rising flag is set (YES at 3208), the off flag and rising flag of the down switch 35 are cleared (S2
09), if the up switch 36 is not turned on (3210: YES), the hydraulic pump 2 is driven,
The hydraulic cylinder 1 is operated to lower the loading platform to a predetermined lowering position (S211). On the other hand, when a short circuit occurs in the down switch 35, an LO- signal is sent to the controller 34 to recognize that the down switch 35 is turned on. However, as shown in FIG. 3, when the down switch 35 is short-circuited, (330
1 (No), the off flag of the down switch 35 is not set, and as a result, the down switch 3
5 rising flag cannot be set (N at S302)
O), and as long as the rising flag of the down switch 35 is not set (No in 3208 in Figure 2), the hydraulic cylinder l will not operate to lower the loading platform.Therefore, the short circuit of the down switch 35 will not occur. In this state, even if the parking brake is pulled during a temporary stop such as waiting at a traffic light and the conditions for lowering the platform are met, the platform will not start lowering automatically. Next, the operation for returning the loading platform to its normal height will be described with reference to the flowchart in FIG. In addition,
This loading platform height return operation routine follows the loading platform lowering condition routine. The vehicle height is basically restored by operating the amplifier switch 36. Specifically, the low pressure side pressure switch 38
The signal from the vehicle indicates that the loading platform is at the normal height position, there is no OW signal (No in S401), the vehicle is not returning to the vehicle height (No in S402), and the vehicle is not in a running state (S401). 403 (NO), up switch 3
6 is applied (S404: YES), if the parking brake is pulled at this time (S4
05: YES), drives hydraulic pump 2 and hydraulic cylinder 1.
can be activated to return the loading platform to its normal height (S
406). The vehicle height is restored when the vehicle is securely stopped. Furthermore, even if the up switch 36 is not turned on, if the vehicle is not stopped or the parking brake is released and the vehicle is ready to start driving (S4
03), the loading platform is forcibly returned to the normal position (S406). This is to prevent the vehicle from starting to move with the cargo platform lowered. When the loading platform is returned to its normal height, the hydraulic pressure for operating the biloft valve 25 that closes the passage 13 of the piston 6 of the hydraulic cylinder 1 is released, and the piston upper chamber 11 of the hydraulic cylinder 1 is closed. and the piston lower chamber 12 are communicated via a passage 13. Therefore, in this state, the hydraulic cylinder 1 functions as a shock absorber. Also, when adjusting the vehicle height, please use the pressure switch 37.
38 detects the pressure in the piston upper chamber 11 of the hydraulic cylinder 1 to detect the height of the loading platform and control the device. Therefore, if an abnormality occurs in these pressure switches 37 and 38 and the height position of the loading platform cannot be detected properly, the device will not be able to operate normally. For example, if the low-pressure side pressure switch 38 has a short-circuit failure in the LO-signal manual state that recognizes that the cargo bed has returned to its normal height, the cargo bed can be automatically returned to its normal height when starting. Even if a system is in place, a situation may occur where the vehicle is driven with the cargo platform in the lowered position. This is because the controller 34 mistakenly recognizes that the loading platform is located at the normal height. In this case, as described above, problems such as a significant deterioration in running stability occur. Therefore, in this example, in order to prevent such a situation and further enhance the safety of the system, a fail-safe system is provided in the event of a pressure switch abnormality. Specifically, input signals from the high-pressure side pressure switch 37 and the low-pressure side pressure switch 38 are compared, and if the combination is inappropriate, the loading platform is forcibly returned to the normal height. In particular, the system is configured to be incorporated into the platform lowering routine. That is, as shown in FIG. 2, the high pressure side pressure switch 3
When it is determined that the loading platform is in the lowered position by the pressure detection by 7 (YES in 5201), the low pressure side pressure switch 3
8 fail detection is performed (3212). Here, if the signal from the low pressure side pressure switch 38 is the LO- signal (YES in S212), the loading platform is forcibly returned to the normal position (3213) , even though the pressure in the piston upper chamber 11 of the hydraulic cylinder 1 is detected by the high-pressure side pressure switch 37 to be equal to or higher than the upper limit threshold.
The signal from the low pressure side pressure switch 38 is transmitted to the hydraulic cylinder 1.
The pressure in the piston upper chamber 11 is below the lower limit threshold and the LO- signal indicating that the loading platform is located at the normal height will not occur unless the low-pressure side pressure switch 38 is short-circuited. This is because it cannot happen. Note that this example is an example of a fail-safe system when only the low-pressure side pressure switch 38 has a short-circuit failure. In addition, if the low pressure side pressure switch 3 is not short-circuited, the signal from the low pressure side pressure switch 38 is LOW.
There is no signal (FIG. 2, NO at 5212), and needless to say, the forced return system does not operate in this case. By the way, when adjusting the height of the loading platform,
In the present invention, as mentioned above, when the loading platform is lowered,
The vehicle height lowering indicator lamp 42 is turned on, but its control is as follows.
This is done as follows. This will be explained with reference to the flowchart in FIG. The signal from the high pressure side pressure switch 37 is applied to the hydraulic cylinder l.
This is the old Gl+ signal indicating that the pressure in the upper piston chamber 11 of the piston is at a predetermined upper limit threshold value, in other words, that the loading platform is located at a predetermined lowered position (YES at S l 01), and when traveling. If it is not among them (S 1
03 (NO), the vehicle height lowering indicator lamp 42 is turned on. Also, the signal from the high pressure side pressure switch 37 is
Even if the signal is not 1 signal (No in S 101), if the signal from the low-pressure side pressure cusp inch 38 is not a LOW signal indicating that the pressure in the piston upper chamber ll of the hydraulic cylinder l is below a predetermined lower limit threshold. (No in SIO2),
That is, if the cargo platform is being lowered and the vehicle is not running (No in S103), the vehicle height lowering indicator lamp 42 is turned on (310) in the same manner as above.
5). In this case, the vehicle height lowering indicator lamp 42 may be made to blink so as to be clearly distinguishable from the state in which the cargo platform has already been lowered to a predetermined position. On the other hand, from the high pressure side pressure switch 37 above) 11GI+@
Even if the signal is input, or the low pressure side pressure switch 38
Even if the human power signal from the vehicle is not the above-mentioned L〇- signal, as a general rule, the vehicle height lowering indicator lamp 42 will not be lit while the vehicle is traveling, due to the temporary pressure increase in the hydraulic cylinder 1 due to vibrations during traveling. This is to eliminate the confusion caused by the lamps turning on one after another. However, when the old GH signal is input manually from the high-pressure side pressure switch 37 while driving, or when the 111GH signal is input from the low-pressure side pressure switch 38, which indicates that the pressure value has become higher than the predetermined lower limit threshold. If a signal is input (YES in S101, N02S in 3102)
103: YES), the pressure inside the hydraulic cylinder 1 is detected until a predetermined time has elapsed (S104: No), and if the same state continues even after the predetermined time has elapsed (S10).
4: YES), and turn on the vehicle height lowering indicator lamp 42 (
S105). This is because it is thought that an abnormality has occurred in the device and the loading platform has begun to lower. On the other hand, if the pressure value in the hydraulic cylinder 1 returns to the predetermined value or less within the predetermined time (YES in S101 and N023102), the vehicle height reduction indicator lamp 42 will not be lit (3106), and the temporary This is because it can be considered as an increase in pressure. That is, in the present invention, the vehicle height lowering indicator lamp 42 is prevented from being erroneously turned on while the vehicle is running, and therefore, there is no need to confuse the driver due to the lighting of the lamp while the vehicle is running. In addition, if a malfunction occurs in the device and the cargo platform begins to lower while driving, this abnormality is detected and the vehicle height lowering indicator lamp 42 is turned on to notify the driver of the occurrence of the abnormal situation. Safety is improved because the driver can immediately take measures such as stopping the vehicle. It should be noted that the scope of the present invention is not limited to the above-described embodiments; for example, the vehicle height lowering indicator lamp may of course be made to blink when an abnormal situation occurs while the vehicle is running. Further, in the embodiment, a vehicle height lowering indicator lamp is specially provided, but for example, the down switch itself may be turned on, and the vehicle height lowering indicator lamp may be configured by the switch. Furthermore, it goes without saying that the specific structure of the vehicle height adjustment device is not particularly important.

[Brief explanation of drawings]

1 to 4 are flowcharts for explaining the operation of the vehicle height adjustment device according to the embodiment of the present invention, FIG. 5 is a diagram of the device according to the embodiment viewed from the side of the vehicle, and FIG. A diagram schematically showing the overall configuration of the device according to the embodiment, FIG. 7 is a longitudinal sectional view of the hydraulic cylinder according to the embodiment, and FIG. 8 is an enlarged view of the piston rod and piston of the hydraulic cylinder in FIG. 7. FIG. 9 is a system circuit diagram of the device according to the embodiment. 1... Hydraulic cylinder, 2... Hydraulic pump, 3...
Control means, 5... Cylinder, 8... Piston rond, 11... Piston upper chamber, 37.38... Pressure sensor (pressure switch), 42... Vehicle height lowering indicator lamp.

Claims (1)

[Claims] (1) A hydraulic cylinder is interposed between the vehicle body and the unsprung member, and the lower end of the cylinder is connected to the unsprung member, and the upper end of the piston rod is connected to the vehicle body. , a hydraulic pump that moves oil up and down the piston rod by sending oil into the piston upper chamber of the cylinder or suctioning oil from the piston upper chamber, and a pressure sensor that detects the pressure inside the piston upper chamber;
a control means for controlling the hydraulic pump so as to determine a vehicle height state based on information from the pressure sensor and to adjust the vehicle height between a normal height and a predetermined lowering position; , a vehicle height adjustment device equipped with a vehicle height lowering indicator lamp that flashes or lights up, while the vehicle height lowering indicator lamp is not illuminated while driving, the pressure in the upper chamber of the piston of the hydraulic cylinder is reduced while driving. becomes higher than a predetermined value, the pressure in the piston upper chamber is detected again after a predetermined time has elapsed, or continuously until the predetermined time has elapsed, and if the pressure in the piston upper chamber is still higher than the predetermined value, A method for controlling a vehicle height lowering indicator lamp in a vehicle height adjusting device, characterized in that the vehicle height lowering indicator lamp is made to blink or turn on.