JP7548158B2 - Industrial Vehicles - Google Patents

Description

This disclosure relates to industrial vehicles.

The vehicle disclosed in Patent Document 1 includes a hydraulic device, an operating member, a control device, and a notification device. The hydraulic device includes a hydraulic actuator and a supply/discharge member that supplies/discharges hydraulic oil to/from the hydraulic actuator. When the operating member is operated, the control device controls the supply/discharge member so that hydraulic oil corresponding to the amount of operation of the operating member is supplied to the hydraulic actuator. The control device determines whether or not the hydraulic actuator is operating in accordance with the operation of the operating member. If the hydraulic actuator is not operating in accordance with the operation of the operating member, the control device issues a notification via the notification device.

JP 2007-314316 A

When hydraulic equipment breaks down, replacement hydraulic equipment is ordered. Then, when the replacement hydraulic equipment is delivered, the broken hydraulic equipment is replaced with that hydraulic equipment. If replacement hydraulic equipment is ordered after a hydraulic equipment breaks down, work using the hydraulic equipment cannot be performed until the replacement hydraulic equipment is delivered.

The industrial vehicle that solves the above problem is an industrial vehicle equipped with hydraulic equipment, the hydraulic equipment including a hydraulic actuator that operates with hydraulic oil and a supply/discharge member that supplies/discharges hydraulic oil to the hydraulic actuator, the industrial vehicle including a sensor that detects the operating speed of the hydraulic actuator, and a control device, the control device derives a predicted value of the operating speed of the hydraulic actuator from the operating amount of the supply/discharge member, derives a speed difference between the operating speed detected by the sensor and the predicted value, and derives the notification threshold from the reference value, the grace period, and the increase in the speed difference over time, where the control device is configured to issue a notification when the speed difference is greater than the notification threshold, where a predetermined value of the speed difference that corresponds to when the hydraulic equipment breaks down is a reference value, a value smaller than the reference value is a notification threshold, and a predetermined period from the notification threshold to the reference value is a grace period.

Even if the amount of movement of the supply and discharge members is the same, the movement speed of the hydraulic actuator decreases as the hydraulic equipment deteriorates. Therefore, as the hydraulic equipment deteriorates, the speed difference increases. The larger the speed difference, the more likely the hydraulic equipment is to break down. If the hydraulic equipment is continued to be used with the speed difference exceeding the reference value, the hydraulic equipment may break down. The control device issues a notification when the speed difference is greater than the notification threshold. The notification threshold is a value smaller than the reference value. The notification threshold is derived from the reference value, the grace period, and the increase in the speed difference over time. The increase in the speed difference over time varies depending on the environment in which the industrial vehicle is used, the usage status of the industrial vehicle, etc. By deriving the notification threshold from the increase in the speed difference over time, it is possible to set a notification threshold suited to the industrial vehicle. By ordering hydraulic equipment after the notification, the manager of the industrial vehicle can order the hydraulic equipment before the speed difference reaches the reference value. Therefore, it is less likely that a situation will occur in which work using hydraulic equipment cannot be performed.

Regarding the above industrial vehicle, the industrial vehicle may be a forklift, the forklift may be equipped with a loading device, and the hydraulic actuator may be a hydraulic cylinder equipped with the loading device.

For the above industrial vehicle, the control device may be configured to derive a correlation between the amount of movement of the supply/discharge member and the operating speed detected by the sensor during a predetermined time from the start of use of the hydraulic equipment, the correlation being used to derive the predicted value and being a correlation between the amount of movement of the supply/discharge member and the operating speed.

The present invention makes it less likely that situations will arise in which work using hydraulic equipment cannot be carried out.

FIG. 1 is a block diagram illustrating an industrial vehicle. FIG. 2 is a diagram showing a configuration of a control valve unit. 10 is a flowchart showing a procedure of a notification control process performed by the control device. FIG. 13 is a diagram showing a notification threshold value set by notification control. FIG. 13 is a diagram showing a notification threshold value set by notification control. 4 is a flowchart showing a procedure of correlation derivation control performed by the control device.

An embodiment of an industrial vehicle will be described.
As shown in FIG. 1 , the industrial vehicle 10 includes a loading device 20, a lift lever 11, a tilt lever 12, and a notification device 13. The industrial vehicle 10 is a forklift. The industrial vehicle 10 is operated by a passenger. The loading device 20 includes a mast 21, a fork 22, and a hydraulic device 30. The fork 22 is attached to the mast 21. The lift lever 11 is operated, for example, by the passenger of the industrial vehicle 10. The lift lever 11 is operated when the mast 21 is raised or lowered. The tilt lever 12 is operated, for example, by the passenger of the industrial vehicle 10. The tilt lever 12 is operated when the mast 21 is tilted. The notification device 13 notifies the passenger of the industrial vehicle 10. Examples of the notification device 13 include a display unit, a buzzer, and a lamp.

The hydraulic equipment 30 includes a lift cylinder 31 , a tilt cylinder 34 , a tank 38 , a pump 39 , a motor 40 , and a control valve unit 41 .
The lift cylinder 31 is a hydraulic cylinder. The lift cylinder 31 includes a bottom chamber 32 and a rod 33. The rod 33 moves when hydraulic oil is supplied to or discharged from the bottom chamber 32. The mast 21 moves up and down when the rod 33 of the lift cylinder 31 moves up and down. The forks 22 move up and down together with the mast 21. The lift cylinder 31 is a hydraulic actuator.

The tilt cylinder 34 is a hydraulic cylinder. The tilt cylinder 34 has a first chamber 35, a second chamber 36, and a rod 37. The rod 37 moves when hydraulic oil is supplied to and discharged from the first chamber 35 and the second chamber 36. The mast 21 tilts when the rod 37 of the tilt cylinder 34 moves. The fork 22 tilts together with the mast 21. The tilt cylinder 34 is a hydraulic actuator.

The tank 38 stores hydraulic oil.
The pump 39 pumps the hydraulic oil from the tank 38. The hydraulic oil pumped by the pump 39 is supplied to the control valve unit 41.

The motor 40 is an electric motor. The motor 40 drives the pump 39.
2 , the control valve unit 41 includes a lift valve 42 and a tilt valve 51. The hydraulic device 30 includes a first oil passage 43, a second oil passage 44, a supply/discharge passage 45, a third oil passage 52, a fourth oil passage 53, a first supply/discharge passage 54, and a second supply/discharge passage 55.

The lift valve 42 is a manual switching valve that switches the direction of hydraulic oil flow depending on the operating state of the lift lever 11. A first oil passage 43 is connected to the lift valve 42. Hydraulic oil discharged from the pump 39 flows through the first oil passage 43. The lift valve 42 is supplied with hydraulic oil discharged from the pump 39 through the first oil passage 43. A second oil passage 44 is connected to the lift valve 42. The second oil passage 44 is connected to the tank 38. Hydraulic oil discharged from the lift cylinder 31 flows through the second oil passage 44. A supply and discharge passage 45 is connected to the lift valve 42. The supply and discharge passage 45 is connected to the bottom chamber 32 of the lift cylinder 31. By supplying hydraulic oil to the bottom chamber 32 through the supply and discharge passage 45, the rod 33 moves so that the mast 21 rises. By discharging hydraulic oil from the bottom chamber 32 through the supply and discharge passage 45, the rod 33 moves so that the mast 21 descends.

The lift valve 42 can be switched to any one of a neutral position, an elevated position, and a lowered position. The neutral position is a position where hydraulic oil is not supplied from the pump 39 to the bottom chamber 32, and hydraulic oil is not discharged from the bottom chamber 32. The elevated position is a position where hydraulic oil is supplied from the pump 39 to the bottom chamber 32. The lowered position is a position where hydraulic oil is discharged from the bottom chamber 32. The lift valve 42 is switched between the neutral position, the elevated position, and the lowered position by the movement of a spool connected to the lift lever 11.

The tilt valve 51 is a manual switching valve that switches the direction of hydraulic oil flow depending on the operating state of the tilt lever 12. A third oil passage 52 is connected to the tilt valve 51. Hydraulic oil discharged from the pump 39 flows through the third oil passage 52. The tilt valve 51 is supplied with hydraulic oil discharged from the pump 39 through the third oil passage 52. A fourth oil passage 53 is connected to the tilt valve 51. The fourth oil passage 53 is connected to the tank 38. Hydraulic oil discharged from the tilt cylinder 34 flows through the fourth oil passage 53. A first supply and discharge passage 54 is connected to the tilt valve 51. The first supply and discharge passage 54 is connected to the first chamber 35 of the tilt cylinder 34. A second supply and discharge passage 55 is connected to the tilt valve 51. The second supply and discharge passage 55 is connected to the second chamber 36 of the tilt cylinder 34. Supplying hydraulic oil to the first chamber 35 through the first supply and discharge passage 54 moves the rod 37 so that the mast 21 tilts forward. Supplying hydraulic oil to the second chamber 36 through the second supply and discharge passage 55 moves the rod 37 so that the mast 21 tilts backward.

The tilt valve 51 can be switched to any one of a neutral position, a forward tilt position, and a backward tilt position. The neutral position is a position where the pump 39 does not supply hydraulic oil to the first chamber 35 and the second chamber 36, and does not discharge hydraulic oil from the first chamber 35 and the second chamber 36. The forward tilt position is a position where the pump 39 supplies hydraulic oil to the first chamber 35. The backward tilt position is a position where the pump 39 supplies hydraulic oil to the second chamber 36. The tilt valve 51 is switched between the neutral position, the forward tilt position, and the backward tilt position by the movement of a spool connected to the tilt lever 12.

As described above, in the hydraulic device 30, hydraulic oil discharged from the pump 39 is supplied to the lift cylinder 31 by the lift valve 42. The lift valve 42 discharges the hydraulic oil from the lift cylinder 31. The tilt valve 51 supplies and discharges the hydraulic oil discharged from the pump 39 to the tilt cylinder 34. The pump 39, the lift valve 42, and the tilt valve 51 are supply and discharge members.

As shown in FIG. 1, the industrial vehicle 10 includes a lifting height sensor 61, a tilt angle sensor 62, a first operation amount sensor 63, a second operation amount sensor 64, a rotation speed sensor 65, a drive unit 66, and a control unit 71.

The height sensor 61 detects the height of the mast 21. The height of the mast 21 is the height from the road surface to the forks 22. The height sensor 61 is, for example, a reel sensor.
The tilt angle sensor 62 detects the tilt angle of the mast 21. The tilt angle is the tilt angle of the mast 21 when the surface on which the industrial vehicle 10 exists and the upper surfaces of the forks 22 are parallel to each other, which is set as a reference angle of 0°. As the tilt angle sensor 62, for example, a potentiometer is used.

The first operation amount sensor 63 detects the amount of operation of the lift lever 11. As the first operation amount sensor 63, for example, a potentiometer is used.
The second operation amount sensor 64 detects the amount of operation of the tilt lever 12. As the second operation amount sensor 64, for example, a potentiometer is used.

The rotation speed sensor 65 detects the rotation speed of the motor 40 .
The driving device 66 is a motor driver that drives the motor 40. The driving device 66 rotates the motor 40 in response to a command from the control device 71. The driving device 66 can acquire the detection result of the rotation speed sensor 65. The driving device 66 controls the motor 40 while grasping the rotation speed of the motor 40.

The control device 71 includes a processor 72, a storage unit 73, and an auxiliary storage device 74. The storage unit 73 includes a random access memory (RAM) and a read only memory (ROM). The storage unit 73 stores program code or instructions configured to cause the processor 72 to execute a process. The storage unit 73, i.e., a computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer. The control device 71 may be configured by a hardware circuit such as an ASIC or an FPGA. The control device 71, which is a processing circuit, may include one or more processors that operate according to a computer program, one or more hardware circuits such as an ASIC or an FPGA, or a combination thereof. Examples of the auxiliary storage device 74 include an electrically erasable programmable read only memory (EEPROM), a hard disk drive, a solid state drive, and a flash memory.

The control device 71 performs notification control. The notification control is control that causes the notification device 13 to issue a notification before the hydraulic equipment 30 breaks down. The notification control is executed, for example, while the hydraulic equipment 30 is in operation. The hydraulic equipment 30 is in operation when at least one of the lift lever 11 and the tilt lever 12 is being operated. The following describes, as an example, the notification control that is executed when the lift lever 11 is being operated.

3, in step S1, the control device 71 derives a predicted value of the operating speed of the lift cylinder 31. The operating speed of the lift cylinder 31 can also be said to be the lifting and lowering speed of the mast 21. A correlation that associates the operating amount of the supply and discharge member related to the operating speed of the lift cylinder 31 with the operating speed of the lift cylinder 31 is stored in the auxiliary memory device 74. The control device 71 derives a predicted value of the operating speed of the lift cylinder 31 from this correlation. The supply and discharge members related to the operating speed of the lift cylinder 31 are the pump 39 and the lift valve 42. The control device 71 sets the rotation speed of the motor 40 as the operating amount of the pump 39. The rotation speed of the motor 40 may be a command value given to the drive device 66 by the control device 71, or may be an actual value detected by the rotation speed sensor 65. The control device 71 sets the operating amount of the lift lever 11 detected by the first operating amount sensor 63 as the operating amount of the lift valve 42. The control device 71 determines the operating speed of the lift cylinder 31 corresponding to the rotation speed of the motor 40 and the amount of operation of the lift lever 11 from the correlation. The operating speed of the lift cylinder 31 determined from the correlation is then set as a predicted value of the operating speed of the lift cylinder 31. The correlation is stored in the auxiliary storage device 74 as a formula or a map.

Next, in step S2, the control device 71 detects the operating speed of the lift cylinder 31. The control device 71 acquires the detection results of the lift height sensor 61 multiple times. This allows the control device 71 to derive the amount of displacement of the lift height. The control device 71 detects the operating speed of the lift cylinder 31 by dividing the amount of displacement by the time that elapsed during which the displacement occurred. The lift height sensor 61 can be considered a sensor that detects the operating speed of the lift cylinder 31. In the following explanation, the difference between the predicted value of the operating speed of the lift cylinder 31 and the operating speed of the lift cylinder 31 obtained from the detection result of the lift height sensor 61 is called the speed difference. The speed difference can also be considered the difference between the predicted value and the actual value.

Next, in step S3, the control device 71 stores the speed difference in the auxiliary storage device 74 in association with the time.
Next, in step S4, the control device 71 derives the increase in the speed difference over time. The speed difference increases with the deterioration of the hydraulic equipment 30. The speed difference occurs, for example, due to an increase in foreign matter contained in the hydraulic oil, wear of the lift valve 42 and the tilt valve 51, and leakage occurring in the lift cylinder 31 and the tilt cylinder 34. Even if the operation amount of the supply and discharge member related to the operation speed of the lift cylinder 31 is the same, the speed difference increases as the operation speed of the lift cylinder 31 decreases. For this reason, the increase in the speed difference over time can also be said to be the decrease in the operation speed of the lift cylinder 31 over time. The increase in the speed difference over time is the increase in the speed difference per unit time. The control device 71 calculates the increase in the speed difference per unit time every time the operation speed of the lift cylinder 31 is obtained in step S2. The unit time can be arbitrarily set by the manager of the industrial vehicle 10, etc. The control device 71 derives the increase in the speed difference over time from the operation speed of the lift cylinder 31 derived in the period going back by a unit time from the time when the processing of step S4 is performed, for example.

Next, in step S5, the control device 71 derives a notification threshold. The notification threshold is the speed difference when a notification is issued by the notification device 13. The notification threshold can be derived from a predetermined reference value, the increase in the speed difference over time derived in step S4, and a grace period, which is a predetermined period.

The reference value is defined as the speed difference at which the hydraulic equipment 30 breaks down. In other words, it is the speed difference that corresponds to when the hydraulic equipment 30 breaks down. A range of speed differences that is assumed to allow the hydraulic equipment 30 to be used without breaking down is determined in advance. The upper limit of this range is the speed difference that corresponds to a breakdown. The speed difference that corresponds to a breakdown can also be said to be a speed difference that is assumed to cause a breakdown in the hydraulic equipment 30 if the hydraulic equipment 30 is continued to be used in a state exceeding this speed difference. The range of speed differences that is assumed to allow the hydraulic equipment 30 to be used without breaking down is derived, for example, by bench testing.

The grace period is the period from when the speed difference reaches the notification threshold to when it reaches the reference value. The grace period is set, for example, based on the lead time. The grace period is set to the lead time or the lead time plus a margin. The lead time is the estimated time required from when the hydraulic equipment 30 is ordered to when the hydraulic equipment 30 is delivered.

The control device 71 can predict the speed difference that will increase during the grace period from the increase in the speed difference over time. The control device 71 derives the notification threshold by subtracting the speed difference that is predicted to increase during the grace period from the reference value. The notification threshold is a value smaller than the reference value.

As shown in Figures 4 and 5, the notification threshold value varies depending on the amount of increase in the speed difference over time. The greater the increase in the speed difference over time, the greater the increase in the speed difference during the grace period T1. Therefore, as shown in Figure 4, the greater the increase in the speed difference over time, the smaller the notification threshold value. As shown in Figure 5, the more slowly the increase in the speed difference over time, the larger the notification threshold value.

As shown in FIG. 3, in step S6, the control device 71 determines whether the speed difference is greater than the notification threshold. If the determination result in step S6 is negative, the control device 71 ends the notification control. If the determination result in step S6 is positive, the control device 71 performs the process of step S7.

In step S7, the control device 71 issues a notification via the notification device 13. If the notification device 13 is a display unit, the control device 71 may issue a display encouraging replacement of the hydraulic equipment 30 or display the time until the speed difference reaches the reference value. If the notification device 13 is a buzzer, the control device 71 may issue a notification by a buzzer sound. If the notification device 13 is a lamp, the control device 71 may issue a notification by turning on or blinking the lamp. When the processing of step S7 is completed, the control device 71 ends notification control.

Note that even if the deterioration of the hydraulic equipment 30 is the same, the speed difference may differ depending on the amount of operation of the supply and discharge members related to the operating speed of the lift cylinder 31. For this reason, the control device 71 may divide the amount of operation of the supply and discharge members related to the operating speed of the lift cylinder 31 into multiple categories, and derive the speed difference and the notification threshold for each category. For example, when the lift lever 11 is operated in a direction to raise the mast 21, the maximum amount of operation may be the first category, and the range of the amount of operation less than the maximum and a predetermined value may be the second category. The predetermined value is a value smaller than the maximum. For convenience of explanation, the amount of operation of the lift lever 11 is taken as an example, but the rotation speed of the motor 40 is also related to the operating speed of the lift cylinder 31. For this reason, when dividing the amount of operation of the supply and discharge members related to the operating speed of the lift cylinder 31 into multiple categories, the category is a combination of the amount of operation of the lift lever 11 and the rotation speed of the motor 40.

The correlation derivation control will be explained. The correlation derivation control is performed to derive the correlation between the operating speed of the hydraulic actuator and the operating amount of the supply and discharge member. As an example, the case of deriving the correlation used in step S1, that is, the correlation between the operating amount of the supply and discharge member related to the operating speed of the lift cylinder 31 and the operating speed of the lift cylinder 31, will be explained.

As shown in FIG. 6, in step S11, the control device 71 determines whether a predetermined time has elapsed since the hydraulic equipment 30 was started to be used. The start of use of the hydraulic equipment 30 is, for example, when the industrial vehicle 10 is manufactured. Also, if the hydraulic equipment 30 is replaced with a new hydraulic equipment 30 due to a failure of the hydraulic equipment 30 after the industrial vehicle 10 is manufactured, the predetermined time is when the hydraulic equipment 30 is replaced. The predetermined time is the time during which the speed difference of the lift cylinder 31 is within the allowable range. In other words, it is the time during which the deterioration of the lift cylinder 31 can be considered not to be progressing. The predetermined time is determined in advance. The elapsed time from the start of use of the hydraulic equipment 30 may be counted when the industrial vehicle 10 is in an activated state. The activated state is a state in which the loading device 20 can be driven. The elapsed time from the start of use of the hydraulic equipment 30 may be counted while the hydraulic equipment 30 is in operation.

In step S12, the control device 71 acquires the amount of operation of the supply and discharge members related to the operating speed of the lift cylinder 31. The amount of operation of the supply and discharge members related to the operating speed of the lift cylinder 31 can be acquired in the same manner as in step S1. That is, the control device 71 acquires the rotation speed of the motor 40 and the amount of operation of the lift lever 11.

Next, in step S13, the control device 71 detects the operating speed of the lift cylinder 31. The operating speed of the lift cylinder 31 can be detected by the same method as in step S2. That is, the control device 71 obtains the detection results of the lift height sensor 61 multiple times and detects the operating speed of the lift cylinder 31 from these detection results.

Next, in step S14, the control device 71 associates the amount of movement of the supply/discharge member related to the operating speed of the lift cylinder 31 obtained in step S12 with the operating speed of the lift cylinder 31 detected in step S13.

In this way, by associating the amount of movement of the supply and discharge members related to the operating speed of the lift cylinder 31 with the operating speed of the lift cylinder 31 multiple times during a predetermined time period from the start of use of the hydraulic equipment 30, it is possible to derive a correlation. The correlation is stored in the auxiliary storage device 74. It can be said that the correlation specifies the correspondence between the amount of movement of the supply and discharge members related to the operating speed of the lift cylinder 31 and the operating speed of the lift cylinder 31 when deterioration of the hydraulic equipment 30 is not progressing.

The operation of this embodiment will be described.
As the hydraulic equipment 30 deteriorates, the speed difference increases. The larger the speed difference, the more likely the hydraulic equipment 30 is to break down. If the hydraulic equipment 30 is continued to be used with the speed difference exceeding the reference value, there is a risk that the hydraulic equipment 30 will break down. The control device 71 issues a notification when the speed difference is larger than the notification threshold. The notification threshold is a value smaller than the reference value. Therefore, a notification can be issued before the hydraulic equipment 30 breaks down.

The effects of this embodiment will be described.
(1) The manager of the industrial vehicle 10 can place an order for the hydraulic equipment 30 after receiving the notification, and can place an order for the hydraulic equipment 30 before the speed difference reaches the reference value. An order for a replacement hydraulic equipment 30 can be placed before the hydraulic equipment 30 breaks down. Therefore, it is unlikely that a situation will arise in which work using the hydraulic equipment 30 cannot be performed until the replacement hydraulic equipment 30 is delivered, and a deterioration in work efficiency can be suppressed.

(2) The notification threshold is derived from the reference value, the grace period, and the increase in the speed difference over time. The increase in the speed difference over time may differ for each user depending on the environment in which the industrial vehicle 10 is used, the usage conditions of the industrial vehicle 10, and the like. For this reason, if the notification threshold is set uniformly, the notification will be given too early for a user who uses the industrial vehicle 10 so that the speed difference increases gradually. As in this embodiment, if the notification threshold is derived from the grace period and the increase in the speed difference over time, the notification is given the grace period earlier than the speed difference reaches the reference value. In other words, regardless of the increase in the speed difference over time, the notification is given the grace period earlier than the speed difference reaches the reference value. The notification threshold can be set for each individual industrial vehicle 10. Notification can be given according to the environment and usage conditions of the industrial vehicle 10.

(3) The control device 71 can provide a notification before the hydraulic equipment 30 fails. By replacing the hydraulic equipment 30 with a new hydraulic equipment 30 before the hydraulic equipment 30 fails, it is possible to prevent the hydraulic equipment 30 from failing. This makes it possible to prevent the leakage of hydraulic oil due to the failure of the hydraulic equipment 30.

(4) The control device 71 derives the correlation for a predetermined time from the start of use of the hydraulic equipment 30. The types of motor 40, lift valve 42, and tilt valve 51 may differ depending on the hydraulic equipment 30. It is difficult to derive the correlation in advance for all combinations according to the types of motor 40, lift valve 42, and tilt valve 51. The control device 71 derives the correlation from the track record of the operation amount and operation speed of the supply and discharge member, so that the correlation according to the type of motor 40, lift valve 42, and tilt valve 51 is derived without having to derive the correlation in advance.

The embodiment can be modified as follows: The embodiment and the following modified examples can be combined with each other to the extent that there is no technical contradiction.
The correlation between the movement amount of the supply/discharge member related to the movement speed of the lift cylinder 31 and the movement speed of the lift cylinder 31 may be determined in advance during the manufacturing stage of the industrial vehicle 10. If the motor 40, the lift valve 42, and the tilt valve 51 of the hydraulic device 30 are known, the correlation can be derived in advance. Therefore, the correlation may be determined in advance.

○ Notification control may be performed using the tilt cylinder 34. In this case, the control device 71 performs notification control based on the speed difference between the predicted value of the operating speed of the tilt cylinder 34 and the operating speed of the tilt cylinder 34 detected by the tilt angle sensor 62. The predicted value of the operating speed of the tilt cylinder 34 may be derived from a correlation that associates the operating amount of the supply and discharge member related to the operating speed of the tilt cylinder 34 with the operating speed of the tilt cylinder 34. The correlation can be derived by correlation derivation control. In this case, the control device 71 derives the correlation by associating the operating amount of the supply and discharge member related to the operating speed of the tilt cylinder 34 with the operating speed of the tilt cylinder 34. The supply and discharge members related to the operating speed of the tilt cylinder 34 are the pump 39 and the tilt valve 51. The control device 71 sets the rotation speed of the motor 40 as the operating amount of the pump 39. The control device 71 regards the amount of operation of the tilt lever 12 detected by the second operation amount sensor 64 as the amount of operation of the tilt valve 51. The control device 71 acquires the detection results of the tilt angle sensor 62 multiple times. This allows the control device 71 to derive the amount of displacement of the tilt angle of the mast 21. The control device 71 detects the operating speed of the tilt cylinder 34 by dividing the amount of displacement by the time that elapsed while the displacement occurred. The tilt angle sensor 62 is a sensor that detects the operating speed of the tilt cylinder 34.

The control device 71 may perform notification control using the tilt cylinder 34 instead of notification control using the lift cylinder 31. The control device 71 may perform notification control using the tilt cylinder 34 in addition to notification control using the lift cylinder 31.

The industrial vehicle 10 may be a construction machine. In this case, the construction machine is equipped with at least one of a hydraulic cylinder and a hydraulic motor. The hydraulic cylinder and the hydraulic motor are hydraulic actuators.

The industrial vehicle 10 may be automatically driven by the control device 71. In this case, the notification device 13 may be a communication device capable of transmitting information to a higher-level control device that issues commands to the industrial vehicle 10. When the speed difference exceeds the notification threshold, the control device 71 transmits information indicating that the speed difference has exceeded the notification threshold to the higher-level control device. The higher-level control device notifies the manager of the industrial vehicle 10. The notification at this time may be performed using a display unit, a buzzer, or a lamp.

The industrial vehicle 10 may be remotely operated. In this case, an operator operates the industrial vehicle 10 at a remote location away from the industrial vehicle 10. The operator operates the industrial vehicle 10 by operating an operation terminal provided at the remote location. In this case, the notification device 13 may be a communication device capable of transmitting information to the operation terminal. When the speed difference exceeds the notification threshold, the control device 71 transmits information indicating that the speed difference has exceeded the notification threshold to the operation terminal. The operation terminal notifies the manager of the industrial vehicle 10. The notification at this time may be performed using a display unit, a buzzer, or a lamp.

The lift valve 42 may operate the spool using a solenoid or hydraulic pressure in response to the amount of operation of the lift lever 11. Similarly, the tilt valve 51 may operate the spool using a solenoid or hydraulic pressure in response to the amount of operation of the tilt lever 12.

The control device 71 may detect the operating speed of the lift cylinder 31 from the detection result of a stroke sensor built into the lift cylinder 31. The control device 71 can derive the displacement amount of the lift cylinder 31 from the detection result of the stroke sensor. The control device 71 detects the operating speed of the lift cylinder 31 by dividing the displacement amount by the time that elapsed during which the displacement amount occurs.

The control device 71 may detect the operating speed of the tilt cylinder 34 from the detection result of a stroke sensor built into the tilt cylinder 34. The control device 71 can derive the amount of displacement of the tilt cylinder 34 from the detection result of the stroke sensor. The control device 71 detects the operating speed of the tilt cylinder 34 by dividing the amount of displacement by the time that elapsed during which the amount of displacement occurs.

The industrial vehicle may be an engine-powered forklift.
The reference value may be a speed difference corresponding to a failure of a part of the hydraulic device 30. For example, the reference value set corresponding to the speed difference of the lift cylinder 31 may be a speed difference corresponding to a failure of the lift cylinder 31.

The increase in the speed difference over time can also be considered as the decrease in the operating speed of the lift cylinder 31 over time when the operating amount of the supply and discharge members related to the operating speed of the lift cylinder 31 is kept constant. Therefore, the control device 71 may perform notification control based on the decrease in the operating speed of the lift cylinder 31 over time when the operating amount of the supply and discharge members related to the operating speed of the lift cylinder 31 is kept constant.

10... industrial vehicle, 20... loading and unloading device, 30... hydraulic equipment, 31... hydraulic actuator and lift cylinder which is a hydraulic cylinder, 34... hydraulic actuator and tilt cylinder which is a hydraulic cylinder, 39... pump which is a supply and discharge member, 42... lift valve which is a supply and discharge member, 51... tilt valve which is a supply and discharge member, 61... lift sensor which is a sensor, 62... tilt angle sensor which is a sensor, 71... control device.

Claims (3)

An industrial vehicle equipped with hydraulic equipment,
The hydraulic equipment includes:
A hydraulic actuator operated by hydraulic fluid;
A supply and discharge member that supplies and discharges hydraulic oil to and from the hydraulic actuator,
The industrial vehicle is
A sensor for detecting an operating speed of the hydraulic actuator;
A control device,
The control device includes:
Deriving a predicted value of an operating speed of the hydraulic actuator from the operating amount of the supply/discharge member;
Deriving a speed difference between the motion speed detected by the sensor and the predicted value;
A predetermined value of the speed difference corresponding to when the hydraulic device breaks down is defined as a reference value, a value smaller than the reference value is defined as a notification threshold value, and a predetermined period during which the speed difference changes from the notification threshold value to the reference value is defined as a grace period. The notification threshold value is derived from the reference value, the grace period, and an increase in the speed difference over time.
The industrial vehicle configured to provide a notification if the speed difference is greater than the notification threshold. The industrial vehicle is a forklift,
The forklift is equipped with a loading device,
The industrial vehicle according to claim 1 , wherein the hydraulic actuator is a hydraulic cylinder provided in the loading device. The control device includes:
3. The industrial vehicle according to claim 1, further comprising: a sensor for detecting a correlation between the amount of movement of the supply/discharge member and the operating speed of the supply/discharge member detected by the sensor during a predetermined time period from the start of use of the hydraulic equipment, the correlation being for deriving the predicted value.

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