JP7256606B2 - forklift - Google Patents

Description

The present invention relates to a forklift having a power steering system.

For example, Patent Literature 1 describes a forklift equipped with a power steering device that steers steering wheels according to rotation of a steering wheel. The power steering device described in Patent Document 1 is a full-hydraulic power steering device in which a hydraulic oil supply unit supplies an amount of oil corresponding to the amount of rotation of a steering wheel to a steering cylinder to steer a steered wheel. It is equipped with a steering wheel angle correction system that corrects deviations in correspondence between the steering wheel angle and the tire angle of the steered wheels according to position.

JP 2008-162587 A

In the forklift described in Patent Document 1, the power steering mechanism detects the steering wheel angle, and according to the detection result, based on the stored correspondence information between the steering wheel angle and the tire angle of the steered wheels, the hydraulic pressure is adjusted. Steering is performed by controlling the device. Also, the correspondence between the actual steering wheel angle and the tire angle of the steered wheels may deviate from the stored correspondence information. I do.

This correction is performed by steering the tire angle from the maximum value (one end) to the minimum value (the other end), detecting the steering wheel angle and tire angle at both ends of the tire angle, and storing the detected results. Corrects the correspondence information that is However, if the tire angle is steered to both ends, the tire hits the end and hydraulic oil leaks and the steering wheel spins, which may prevent accurate correction information from being obtained. Therefore, the forklift described in Patent Document 1 has a problem that accurate correction cannot be performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a forklift capable of more accurately correcting the relationship between the steering wheel angle and the tire angle.

In order to solve the above-mentioned problems, a forklift according to one aspect of the present invention is a forklift having a power steering device equipped with a hydraulic device that steers steering wheels according to rotation of a steering wheel, and detects a steering wheel angle of the steering wheel. a steering wheel angle sensor, a tire angle sensor for detecting the tire angle of the steered wheels, storage means for storing the initial relationship between the steering wheel angle and the tire angle in the steering angle range of the steered wheels, the straight traveling position of the steered wheels, a first acquisition means for acquiring detection results of the steering wheel angle sensor and the tire angle sensor at the measurement position and the second measurement position; and correction means for correcting the initial relationship stored in the storage means based on the acquisition results of the acquisition means. , has The first measurement position is set between the straight-ahead position and the maximum steering angle position and does not include the maximum steering angle position, and the second measurement position is a position between the straight-ahead position and the minimum steering angle position. It is set to a position that does not include the minimum steering angle position.

Arbitrary combinations of the above constituent elements, and mutually replacing the constituent elements and expressions of the present invention in methods, systems, etc. are also effective as aspects of the present invention.

According to the present invention, it is possible to provide a forklift that can more accurately correct the relationship between the steering wheel angle and the tire angle.

1 is a side view showing a forklift according to an embodiment; FIG. 2 is a block diagram showing the configuration of the forklift in FIG. 1; FIG. FIG. 2 is a configuration diagram showing a configuration of a steering mechanism of the forklift in FIG. 1; FIG. 2 is a flow chart showing an example of a setting control operation of the forklift of FIG. 1; FIG. 5 is a screen diagram showing an example of a display screen for the setting control operation of FIG. 4; FIG. FIG. 4 is a flow chart showing an example of an acquisition operation of the steering mechanism of FIG. 3; FIG. FIG. 7 is a screen diagram showing an example of a display screen for the acquisition operation of FIG. 6; FIG. 4 is a graph showing an example of the relationship between the steering wheel angle and the tire angle of the steering mechanism of FIG. 3; FIG. 4 is a flow chart showing an example of a predetermined value setting operation of the steering mechanism of FIG. 3; FIG. 10 is a screen diagram showing an example of a display screen for the predetermined value setting operation of FIG. 9; FIG. 4 is a flow chart showing an example of relationship learning operation of the steering mechanism of FIG. 3; FIG. FIG. 12 is a screen diagram showing an example of a display screen for the relationship learning operation of FIG. 11; FIG. 4 is a flow chart showing an example of a knob misalignment correcting operation of the steering mechanism of FIG. 3; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on preferred embodiments with reference to the drawings. In the embodiment and modified examples, the same or equivalent constituent elements and members are denoted by the same reference numerals, and redundant explanations are omitted as appropriate. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in each drawing, some of the members that are not important for explaining the embodiments are omitted.
Also, terms including ordinal numbers such as first, second, etc. are used to describe various components, but these terms are used only for the purpose of distinguishing one component from other components, and the terms The constituent elements are not limited by

In the following description, "parallel" and "perpendicular" include not only perfectly parallel and perpendicular, but also deviate from parallel and perpendicular within a margin of error. Moreover, "substantially" means that they are the same within an approximate range.

[Embodiment]
First, the overall configuration of a forklift 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. FIG. 1 is a side view schematically showing a forklift 100. FIG. FIG. 2 is a block diagram showing the configuration of the forklift 100. As shown in FIG. FIG. 3 is a configuration diagram showing the configuration of the steering mechanism 10 of the forklift 100. As shown in FIG. The traveling direction of the forklift 100 may be called "front" and "rear", and the vehicle height direction may be called "upper" and "lower". Such directional notation does not limit the posture in which the forklift 100 is used, and the forklift 100 can be used in any posture depending on the application. As shown in FIG. 1, the forklift 100 is a so-called counterbalance forklift. The forklift 100 mainly includes a vehicle body 20 and a cargo handling section 60 .

(Cargo handling department)
The cargo handling section 60 is provided at the front portion of the vehicle body 20 . The cargo handling section 60 includes a fork 62 , a mast 64 and an elevating cylinder 66 . The fork 62 is inserted into a fork pocket (insertion hole) of a pallet on which cargo is placed. The mast 64 supports the fork 62 so that it can move up and down. The elevating cylinder 66 is a hydraulic cylinder for vertically moving the fork 62 along the mast 64 .

(body)
The vehicle body 20 has a steering mechanism 10 , a control section 30 , steering wheels 14 , drive wheels 16 , a driver's seat 24 , a drive mechanism 28 and a hydraulic mechanism 40 . The steering mechanism 10 is a mechanism that steers the steered wheels according to the operation of the steering wheel 12 . The control unit 30 mainly controls the drive mechanism 28, the hydraulic mechanism 40, and the steering mechanism 10 based on the operations of the operator and the detection results of various sensors. The steering mechanism 10 and the control section 30 will be described later.

The steered wheels 14 (rear wheels) are a pair of wheels that are arranged apart from each other in the left and right direction behind the vehicle body 20 . The steered wheels 14 of this embodiment are configured to change their orientation with respect to the vehicle body 20 according to the rotation of the steering wheel 12 . The driving wheels 16 (front wheels) are a pair of wheels that are arranged in front of the vehicle body 20 with a left-right spacing. The drive wheels 16 of this embodiment are driven by a drive mechanism 28 .

The driver's seat 24 is a seat for operating the forklift 100 while the operator is sitting. In front of the driver's seat 24, a lever operation section 18 having a lever for controlling the operation of the cargo handling section 60 and a setting input section 32 having a display for inputting various settings are provided. A pedal operation unit 38 for controlling traveling is provided on the floor of the driver's seat 24 .

(drive mechanism)
The driving mechanism 28 rotates the driving wheels 16 by a motor 28m to cause the forklift 100 to travel. The drive mechanism 28 is arranged between the drive wheels 16 and the steering wheels 14 of the vehicle body 20 . As shown in FIG. 2, the drive mechanism 28 of this embodiment includes a motor 28m and a drive circuit 28c. The motor 28m is a prime mover that causes the forklift 100 to travel by rotationally driving the driving wheels 16 . The motor 28m is rotated by electric power supplied from the battery 28b, and drives the drive wheels 16 under the control of the control section 30. As shown in FIG. The drive circuit 28c is a circuit that drives the motor 28m under the control of the control section 30 . The drive mechanism 28 may include a gear device for decelerating or accelerating the rotation of the motor 28m and transmitting it to the drive wheels 16. As shown in FIG.

(hydraulic mechanism)
As shown in FIG. 3, the hydraulic mechanism 40 includes an oil tank 54, a hydraulic pump 50, a cargo handling motor 60m, and a control valve 46, and supplies pressurized oil to the lifting cylinder 66 of the cargo handling section 60 and the steering mechanism 10. Hydraulic oil discharged from the steering mechanism 10 and the lifting cylinder 66 is returned to the oil tank 54 through lines 42d and 66b. The hydraulic pump 50 is driven by the cargo-handling motor 60 m to pressurize the hydraulic oil from the oil tank 54 and send it to the control valve 46 . The cargo handling motor 60m is rotated by electric power supplied from the battery 28b. The cargo handling motor 60m is driven by a cargo handling drive circuit 60c under the control of the controller 30 (see also FIG. 2). The control valve 46 distributes and delivers the pressurized hydraulic fluid from the hydraulic pump 50 to the steering mechanism 10 and the lifting cylinder 66 . The control valve 46 delivers hydraulic fluid to the P port of the steering valve unit 42 through line 42c and to the lift cylinder 66 through line 66a.

(steering mechanism)
Next, referring to FIG. 3, the steering mechanism 10 will be described. The steering mechanism 10 of this embodiment is a fully hydraulic power steering mechanism. The steering mechanism 10 includes a steering wheel 12, a steering valve unit 42, a solenoid valve 44, a steering cylinder 48, link mechanisms 48e and 48f, a king pin 48j, a steering wheel angle sensor 34, a tire angle sensor 36, and a controller. 30 and mainly include.

(handle)
The steering wheel 12 functions as an annular steering wheel that is rotated by the operator for steering. The handle 12 is provided with a knob 12b for easy operation by the operator. With the knob 12b at a predetermined rotational position, the steered wheels 14 are set to face straight ahead. In this embodiment, the knob 12b is positioned at the 8 o'clock position (60 degrees clockwise from the bottom position) with the steered wheels 14 directed straight ahead. A handle shaft 12 s supporting the handle 12 is connected to the steering valve unit 42 . Hereinafter, the displacement of the knob 12b from the reference position (8 o'clock position) with the steered wheels 14 directed straight ahead is referred to as knob displacement.

(Steering valve unit)
The steering valve unit is a valve unit that delivers hydraulic fluid according to the amount of rotation of the steering wheel 12 . The steering valve unit 42 of this embodiment employs Orbitroll (registered trademark) manufactured by Eaton Corporation. The steering valve unit 42 is directly driven by the steering wheel shaft 12 s and supplies hydraulic oil to the steering cylinder 48 in proportion to the amount of rotation of the steering wheel 12 .

As shown in FIG. 3 , the P port of the steering valve unit 42 is connected to a line 42 c to which hydraulic oil is supplied from the hydraulic pump 50 and the control valve 46 . A T port of the steering valve unit 42 is connected to a line 42 d for discharging hydraulic oil to the oil tank 54 . The steering valve unit 42 and the steering cylinder 48 are connected by two hydraulic lines 42a and 42b. The steering valve unit 42 connected in this manner receives pressurized hydraulic fluid supplied to the P port, and supplies a predetermined amount of hydraulic fluid to either the R port or the L port according to the amount of rotation of the steering wheel. It drives the steering cylinder 48 . Also, hydraulic fluid is recovered from the other of the R port and the L port, and the recovered hydraulic fluid is discharged to the oil tank 54 from the T port.

More specifically, when the steering wheel 12 is turned left, the hydraulic line 42a functions as a feed line for feeding hydraulic oil from the hydraulic pump 50, and the hydraulic line 42b returns hydraulic oil to the hydraulic pump 50. act as a line. Also, when the handle 12 is turned right, the hydraulic line 42b functions as a feed line, and the hydraulic line 42a functions as a return line.

(steering cylinder)
The steering cylinder 48 functions as a hydraulic device that steers the steered wheels 14 . The steering cylinder 48 includes a cylindrical hollow cylinder tube 48a fixed to the vehicle body, a piston 48b reciprocally arranged inside the cylinder tube 48a, a pair of left and right piston rods 48c extending from both ends of the cylinder tube 48a, 48d. Each hydraulic line 42a, 42b communicates with each chamber of a cylinder tube 48a which is divided into two chambers by a piston 48b.

The left and right steering wheels 14 are connected to the tip portions of the respective piston rods 48c, 48d via link mechanisms 48e, 48f. By driving the steering cylinder 48, each steered wheel 14 is steered left and right around the king pin 48j.

(solenoid valve)
The hydraulic lines 42a and 42b are connected by a bypass line 44b, and a solenoid valve 44 as a correction means is provided in the middle of the bypass line 44b. By opening the solenoid valve 44, hydraulic fluid in the hydraulic lines 42a and 42b delivered from the steering valve unit 42 can be bypassed to reduce the hydraulic pressure difference. By reducing this oil pressure difference, the ratio of the amount of displacement of the piston 48b of the steering cylinder 48 to the amount of operation of the steering wheel 12 can be reduced, and the steering wheel 12 can be idly rotated.

The solenoid valve 44 is an electromagnetic valve incorporating a normally closed type solenoid. The solenoid valve 44 cuts off the bypass line 44b when the solenoid is not energized, and opens the bypass line 44b when the solenoid is energized. The solenoid is controlled by the controller 30 . The bypass line 44b may be provided with a throttle valve that throttles the flow rate when the solenoid valve 44 fails while it is open. The solenoid valve 44 may be an electromagnetic valve incorporating a normally open type solenoid.

(steering wheel angle sensor)
A steering wheel angle sensor 34 is a sensor for detecting rotation of the steering wheel 12 . The steering wheel angle sensor 34 may use known means capable of detecting the rotation angle of the steering wheel 12 . The steering wheel angle sensor 34 of this embodiment is an optical rotary encoder that detects the rotation of the steering wheel shaft 12s. A detection result of the steering wheel angle sensor 34 is provided to the control unit 30 .

(tire angle sensor)
The tire angle sensor 36 is a sensor for detecting the tire angle (also called steering angle) of the steered wheels 14 . The tire angle sensor 36 may use known means capable of detecting the tire angle. The tire angle sensor 36 of this embodiment includes a potentiometer (not shown). The tire angle sensor 36 is mounted so as to rotate in accordance with the rotation of the king pin 48j that supports the right steering wheel 14. As shown in FIG. A detection result of the tire angle sensor 36 is provided to the control unit 30 .

(control part)
Next, the controller 30 will be described with reference to FIG. Each block of the control unit 30 shown in FIG. 2 can be realized by hardware such as a CPU (Central Processing Unit) of a computer and other elements and mechanical devices, and is realized by a computer program etc. in terms of software. However, here, the functional blocks realized by their cooperation are drawn. Therefore, those skilled in the art who have read this specification will understand that these functional blocks can be implemented in various ways by combining hardware and software.

The control unit 30 mainly controls the setting control operation, the relationship correction operation, the relationship learning operation, the predetermined value setting operation, and the oil pressure reduction operation in order to increase the correction accuracy of the knob misalignment correction operation, which will be described later. The setting control operation, relationship correction operation, relationship learning operation, predetermined value setting operation, and oil pressure reduction operation will be described later.

The control unit 30 includes a pedal operation acquisition unit 30b, a detection result acquisition unit 30c, a relationship storage unit 30d, a relationship correction unit 30e, a relationship learning unit 30f, a predetermined value setting unit 30h, and a travel control unit. 30j, a valve control unit 30k, a display control unit 30m, a setting input acquisition unit 30n, a hydraulic pressure reduction unit 30p, a lever operation acquisition unit 30r, and a cargo handling control unit 30t.

The pedal operation acquisition unit 30b acquires the operation result from the pedal operation unit 38. FIG. The travel control unit 30j controls the drive circuit 28c based on the result obtained by the pedal operation obtaining unit 30b.

The detection result acquisition unit 30 c acquires detection results of the steering wheel angle sensor 34 and the tire angle sensor 36 . The acquired steering wheel angle is denoted as acquired steering wheel angle Hg, and the acquired tire angle is denoted as acquired tire angle Tg. The acquired steering wheel angle Hg and acquired tire angle Tg represent the actual steering wheel angle and tire angle.

The relationship storage unit 30d is storage means for storing initial relationship data Dm between the steering wheel angle and the tire angle. The initial relationship data Dm is, so to speak, an initial map showing the correspondence relationship between the initially preset stored steering wheel angle Hm and stored tire angle Tm.

The relationship correcting unit 30e acquires and holds the corrected data Dj through the relationship correcting operation, corrects the initial relationship data Dm according to the corrected data Dj, and obtains the corrected relationship data Dc. The post-correction relationship data Dc is a so-called target map showing the correspondence relationship between the post-correction target steering wheel angle Hc and target tire angle Tc.

The valve control unit 30k obtains the target steering wheel angle Hc corresponding to the acquired tire angle Tg based on the post-correction relationship data Dc by the knob deviation correcting operation, and operates the solenoid valve so that the acquired steering wheel angle Hg approaches the target steering wheel angle Hc. 44.

The relationship learning unit 30f generates and holds learned relationship data De from the obtained steering wheel angle Hg and the obtained tire angle Tg obtained for each predetermined angle in accordance with the operator's steering wheel operation by the relationship learning operation. do. Correction accuracy can be further improved by using the learned relationship data De.

The predetermined value setting unit 30h is setting means for setting and changing the predetermined value Dp added to the correction data Dj by performing a predetermined value setting operation.

The display control unit 30m displays predetermined information on the display unit 32d, which is the display of the setting input unit 32 provided in front of the driver's seat 24. FIG. The setting input acquisition unit 30n acquires a predetermined input result from the input unit 32s including push buttons of the setting input unit 32 and the like. The setting input unit 32, the display control unit 30m, and the input unit 32s function as human-machine interfaces in the relationship correction operation, relationship learning operation, and predetermined value setting operation. The display unit 32d and the input unit 32s may be an integrated touch panel.

When the steering angle of the steered wheels reaches a predetermined angle due to the hydraulic pressure reduction operation, the hydraulic pressure reducing section 30p reduces the hydraulic pressure of the hydraulic device that steers the steered wheels. Specifically, when the acquired tire angle Tg of the steered wheels 14 approaches both ends (hereinafter referred to as ends) of the steering range, the hydraulic pressure supplied to the steering cylinder 48 is reduced.

The lever operation acquisition unit 30 r acquires the operation result from the lever operation unit 18 . The cargo handling control unit 30t controls the cargo handling motor 60m via the cargo handling drive circuit 60c of the cargo handling unit 60 based on the acquisition result of the lever operation acquisition unit 30r. The cargo handling motor 60 m drives the hydraulic pump 50 to generate hydraulic pressure and operate the cargo handling section 60 .

(Setting control operation)
Next, with reference to FIG. 4, an example of setting control operation regarding various settings will be described. FIG. 4 is a flowchart showing an example of the setting control operation of this embodiment, and shows the processing S100 related to this operation. FIG. 5 is a screen diagram showing a display screen for the setting control operation.

When the processing S100 is started, the control unit 30 displays the main menu (first screen Sd1) of the setting control operation on the display unit 32d of the setting input unit 32 (step S101). FIG. 5 is an example of the first screen Sd1. This screen displays a selection button for selecting execution of an acquisition operation, a predetermined value setting operation, or a relationship learning operation, and an end button for ending this process.

When the first screen Sd1 is displayed, the control unit 30 determines whether or not the acquisition operation selection button has been operated (step S102). If the acquisition operation selection button is operated (Y in step S102), the control unit 30 proceeds to acquisition operation processing S70. Processing S70 will be described later. In this specification, touching or pressing a button area on the screen is referred to as "operating a button".

If the acquisition operation selection button has not been operated (N in step S102), the control unit 30 determines whether or not the predetermined value setting operation selection button has been operated (step S103). When the selection button for the predetermined value setting operation is operated (Y in step S103), the control unit 30 advances to processing S80 for the predetermined value setting operation. Processing S80 will be described later.

If the selection button for the predetermined value setting operation has not been operated (N in step S103), the control unit 30 determines whether or not the selection button for the relationship learning operation has been operated (step S104). When the relationship learning operation selection button is operated (Y in step S104), the control unit 30 proceeds to the relationship learning operation process S90. Processing S90 will be described later.

If the selection button for the relationship learning operation has not been operated (N in step S104), the control unit 30 determines whether or not the end button for the setting control operation has been operated (step S105). If the end button for the setting control operation has not been operated (N in step S105), the control unit 30 returns the process to the beginning of step S101, and repeats the processes of steps S101 to S105. When the end button for the setting control operation is operated (Y in step S105), the control unit 30 ends the setting control operation.

These processes are merely examples, and other steps may be added, some steps may be changed or deleted, and the order of steps may be changed.

(Relationship correction operation)
In a forklift, the tire angle-handle angle characteristics of the actual vehicle deviate from the initial relationship data Dm due to variations in the mounting position of the tire angle sensor 36, etc., and the knob deviation correction operation does not operate normally, making vehicle operation difficult. Sometimes. Therefore, in the present embodiment, the tire angle-steering wheel angle characteristic of the actual vehicle is obtained, and based on the result, the relationship correcting operation for correcting the initial relationship data Dm is executed. By executing the relationship correction operation, it is possible to acquire the actual vehicle characteristics and correct the tire angle-steering wheel angle control characteristics in accordance with the actual vehicle characteristics. As a result, knob displacement of the handle 12 can be reduced.

The relationship correction operation includes an acquisition operation for acquiring correction data Dj, and a correction operation for correcting initial relationship data Dm according to correction data Dj to obtain post-correction relationship data Dc. The acquisition operation is to obtain the detection results Hs, H1, H2 of the steering wheel angle sensor 34 and the detection results Ts, T1, T2 of the tire angle sensor 36 at the straight-ahead position Ps of the steered wheels 14, the first measurement position P1 and the second measurement position P2. get.

In order to reduce the influence of errors, it is desirable to obtain the correction data Dj at positions near both ends of the steering range. However, if the steered wheels 14 are steered to both ends of the steering angle range, the steered wheels 14 hit the ends and the hydraulic oil leaks, causing the steering wheel 12 to spin, and accurate information may not be obtained. Therefore, in the present embodiment, the first measurement position P1 is set between the straight-ahead position Ps and the maximum steering angle position Tx and before the maximum steering angle position Tx, and the second measurement position P2 is set to , between the straight ahead position Ps and the minimum steering angle position Tn and before the minimum steering angle position Tn. As an example, the first measurement position P1 and the second measurement position P2 may be 10% to 30% of the steering angle range before the maximum steering angle position Tx and the minimum steering angle position Tn, or further before the steering angle range. may

(acquisition operation)
An example of the acquisition operation will be described with reference to FIGS. 6 and 7. FIG. FIG. 6 is a flowchart showing an example of the acquisition operation of this embodiment, and shows the processing S70 related to this operation. The acquisition operation process S70 may be performed when the forklift 100 is manufactured, may be performed when the forklift 100 is sold, or may be performed when the forklift 100 is maintained. , or any other timing as required.

Processing S70 is started by operating the selection button for the acquisition operation in the setting control operation described above. When the process S70 is started, the control unit 30 displays the second screen Sd2 of the acquisition operation menu on the display unit 32d of the setting input unit 32 (step S71). FIG. 7 is a screen diagram showing an example of the second screen Sd2. The second screen Sd2 displays a display instructing the operator to move the steering wheel to a predetermined position and operate the data acquisition button.

When the second screen Sd2 is displayed, the operator moves the steered wheels 14 to the straight ahead position Ps and operates the acquisition button (step S72). If there is a button operation from the operator, the process proceeds to step S73.

Upon receiving an instruction as the straight-ahead position Ps by an acquisition operation from the operator, the control unit 30 acquires the detection results of the steering wheel angle sensor 34 and the tire angle sensor 36 as the detection results Hs and Ts of the straight-ahead position Ps (step S73). ). After the data is acquired, the processed message may be recolored to a less conspicuous color.

After step S73 is completed, the operator moves the steering wheel 14 to the first measurement position P1 and operates the data acquisition button (step S74). If there is a button operation from the operator, the process proceeds to step S75.

In step S74, if the tire angle is too close to the end of the steering, a warning display may be made to change the first measurement position P1. Specifically, upper and lower thresholds are set for the steering wheel angle and tire angle to be acquired, and when these angles exceed the thresholds, a message to the effect that the thresholds are exceeded is displayed on the display unit 32d, and the steering wheel angle and tire angle are displayed. You may control not to acquire an angle. In this case, it is possible to prevent inaccurate data from being too close to the end.

When receiving an instruction as the first measurement position P1 by operating a button from the operator, the control unit 30 acquires the detection results of the steering wheel angle sensor 34 and the tire angle sensor 36 as the detection results T1 and H1 of the first measurement position P1. (step S75). After the data is acquired, the processed message may be recolored to a less conspicuous color.

After step S75 is completed, the operator moves the steering wheel 14 to the second measurement position P2 and operates the data acquisition button (step S76). If there is a button operation from the operator, the process proceeds to step S77.

In step S76, similarly to step S74, if the steering wheel angle or tire angle exceeds the threshold, the display unit 32d displays that the threshold is exceeded, and the steering wheel angle or tire angle is controlled not to be obtained. good.

Upon receiving an instruction as the second measurement position P2 by operating a button from the operator, the control unit 30 acquires the detection results of the steering wheel angle sensor 34 and the tire angle sensor 36 as the detection results T2 and H2 of the second measurement position P2. (step S77).

When step S77 is completed, the control unit 30 stores the acquired detection results Hs, H1, H2 and detection results Ts, T1, T2 as correction data Dj in the relationship correction unit 30e, and ends the processing S70 (step S78). These processes are merely examples, and other steps may be added, some steps may be changed or deleted, and the order of steps may be changed.

(correction operation)
Next, the correction operation will be explained. The correcting operation in the relationship correcting operation is an operation of obtaining post-correction relationship data Dc from the initial relationship data Dm according to the correction data Dj acquired by the acquisition operation. The correction operation of this embodiment is always executed while the forklift 100 is in operation. The correction operation will be described with reference to FIG. 8 is a graph showing the relationship between the steering wheel angle H and the tire angle T. FIG. In this figure, the horizontal axis is the steering wheel angle H, the positive direction indicates right steering (right rotation), and the negative direction indicates left steering (left rotation). again. The vertical axis represents the tire angle, the positive direction indicates right steering and Re indicates the right end, and the negative direction indicates left steering and Le indicates the left end. In this figure, the solid line indicates the initial relationship data Dm stored in the relationship storage unit 30d, and the black dots (H1, T1), (Hs, Ts), and (H2, T2) indicate the correction data Dj. there is In this way, the correction data Dj can be expressed as coordinates of three points.

In FIG. 8, the post-correction relationship data Dc indicated by broken lines passes through each black dot (H1, T1), (Hs, Ts), and (H2, T2), and the intermediate data between each black dot is the initial relationship It can be obtained by interpolating from the distance ratio from the straight position Ps using the characteristic data Dm. As an example, the tire angle Tm1 corresponding to the steering wheel angle H1 is obtained from the initial relationship data Dm for right steering, and the ratio between T1 and Tm1 is used as a correction ratio, and the initial relationship data Dm is multiplied to obtain the corrected relationship for right steering. Data Dc can be calculated. Similarly, the tire angle Tm2 corresponding to the steering wheel angle H2 is obtained from the initial relationship data Dm for left steering, and the ratio of T2 and Tm2 is used as a correction ratio, and the initial relationship data Dm is multiplied to obtain the corrected relationship for left steering. Data Dc can be calculated.

In the above description of the relationship correction operation, an example of acquiring the relationship between the steering wheel angle and the tire angle at three points, the first and second positions and the straight-ahead position, was shown, but the present invention is not limited to this. In order to improve the accuracy of correction, the relationship between the steering wheel angle and the tire angle may be acquired at four or more points.

(Predetermined value setting operation)
Next, the predetermined value setting operation will be described. For the post-correction relationship data Dc, if the intermediate data between the three black dots is obtained by interpolation, the accuracy of the intermediate data is low and the desired characteristics may be deviated. In order to reduce this divergence, the correction operation of this embodiment includes a process of adding a preset value Dp to intermediate data obtained by interpolation. Therefore, the post-correction relationship data Dc includes the predetermined value Dp. The predetermined value Dp is stored in the predetermined value setting section 30h, and can be arbitrarily set and changed by the predetermined value setting operation.

An example of the predetermined value setting operation will be described with reference to FIGS. 9 and 10. FIG. FIG. 9 is a flowchart showing an example of the predetermined value setting operation of this embodiment, and shows the processing S80 related to this operation. The process S80 is started by operating the selection button for the predetermined value setting operation in the setting control operation described above.

When the processing S80 is started, the control section 30 displays the third screen Sd3 prompting the input of the predetermined value on the display section 32d of the setting input section 32 (step S81). FIG. 10 is a screen diagram showing an example of the third screen Sd3 of the display section 32d of the setting input section 32 in the predetermined value setting operation. The third screen Sd3 includes a graph showing the relationship between the steering wheel angle and the tire angle, a predetermined value Dp of a plurality of points, buttons Bm and Bp for increasing or decreasing the predetermined value Dp, and an end of the predetermined value setting operation. A quit button for and is displayed. The operator can increase or decrease the predetermined value Dp by operating these buttons.

After displaying the third screen Sd3, the control unit 30 determines whether or not the buttons Bm and Bp have been operated (step S82). When the buttons Bm and Bp are operated (Y in step S82), the control unit 30 increases or decreases the predetermined value Dp in response to the operation of the buttons Bm and Bp, and displays the increased or decreased predetermined value Dp on the third screen Sd3. is displayed, and the process returns to the beginning of step S82 (step S83). By repeating steps S82 and S83, the predetermined value Dp is increased or decreased.

If the buttons Bm and Bp have not been operated (N of step S82), the control unit 30 determines whether or not the end button has been operated (step S84). If the end button has not been operated (N of step S84), the control unit 30 returns the process to the beginning of step S82.

If the end button has been operated (Y in step S84), the control unit 30 stores the predetermined value Dp in the predetermined value setting unit 30h and terminates the process S80 (step S85). These processes are merely examples, and other steps may be added, some steps may be changed or deleted, and the order of steps may be changed.

(Relationship learning behavior)
In the above description of the acquisition operation, an example of acquiring the relationship between the steering wheel angle and the tire angle at three points of the first and second positions and the straight-ahead position was shown. It may be acquired. However, for many points, there is a concern that the work of acquiring data for each point is complicated and time-consuming. Therefore, in this embodiment, the relationship learning operation can be selected and executed in place of the acquisition operation described above. The relationship learning operation of the present embodiment is an operation of acquiring detection results of the steering wheel angle sensor and the tire angle sensor for each predetermined angle according to the steering wheel operation of the operator. In this case, the forklift can autonomously learn the detection results of the steering wheel angle sensor and the tire angle sensor at multiple points.

An example of the relationship learning operation will be described with reference to FIGS. 11 and 12. FIG. FIG. 11 is a flowchart showing an example of the relationship learning operation of this embodiment, and shows the processing S90 related to this operation. The acquisition operation process S90 may be performed when the forklift 100 is manufactured, may be performed when the forklift 100 is sold or the like, or may be performed when the forklift 100 is maintained. , or any other timing as required.

The process S90 is started by operating the selection button of the relationship learning operation in the setting control operation described above. When the processing S90 is started, the control unit 30 displays the fourth screen Sd4 of the relationship learning operation menu on the display unit 32d of the setting input unit 32 (step S91). FIG. 12 is a screen diagram showing an example of the fourth screen Sd4. The fourth screen Sd4 instructs the operator to rotate the steering wheel from the neutral position (straight ahead position) to the right end, from the right end to the left end, and from the left end to the neutral position, and to operate the confirmation button at each point. Display is done.

When the fourth screen Sd4 is displayed, the operator rotates the steering wheel 12 from the neutral position (straight ahead position) to the right end (step S92). After rotating the handle 12 to the right end, the operator stops the rotation and operates the confirmation button. When the steering wheel 12 starts to rotate, the control unit 30 continuously acquires the detection results of the steering wheel angle sensor 34 and the tire angle sensor 36 at every predetermined angle (for example, 10 degrees in steering wheel angle) (step S93). When the confirmation button is operated, the control unit 30 holds acquisition results that are continuously acquired. That is, step S92 and step S93 are executed in parallel at substantially the same time.

After operating the confirmation button, the operator rotates the handle 12 from the right end to the left end (step S94). After rotating the handle 12 to the left end, the operator stops the rotation and operates the confirmation button. When the steering wheel 12 starts to rotate, the control unit 30 continuously acquires the detection results of the steering wheel angle sensor 34 and the tire angle sensor 36 at every predetermined angle (step S95). When the confirmation button is operated, the control unit 30 holds acquisition results that are continuously acquired. That is, step S94 and step S95 are executed in parallel at substantially the same time.

After operating the confirmation button, the operator rotates the handle 12 from the left end to the neutral position (step S96). After rotating the handle 12 to the neutral position, the operator stops the rotation and operates the confirmation button. When the steering wheel 12 starts to rotate, the control unit 30 continuously acquires the detection results of the steering wheel angle sensor 34 and the tire angle sensor 36 at every predetermined angle (step S97). When the confirmation button is operated, the control unit 30 holds acquisition results that are continuously acquired. That is, step S96 and step S97 are executed in parallel at substantially the same time.

By executing steps S92 to S97, the control unit 30 can acquire the detection results of the steering wheel angle sensor 34 and the tire angle sensor 36 for one reciprocation for multiple points from the right end to the left end. The data for one round trip may deviate between the outward trip and the return trip. Therefore, the control unit 30 performs a process of aligning the data of the forward route and the return route, stores the processing result in the relationship learning unit 30f as the learned relationship data De, and ends the process S90 (step S98). The process of aligning the data of the forward pass and the return pass may be a process of shifting one to the other, a process of averaging both, or the like. These processes are merely examples, and other steps may be added, some steps may be changed or deleted, and the order of steps may be changed. The predetermined angle can be set according to the desired accuracy of the acquired data. As an example, the predetermined angle may be set within a range of 5° to 20°.

The relationship data De learned by this operation can be used in place of the corrected relationship data Dc in the knob deviation correction operation. Correction accuracy can be improved by using the learned relationship data De. Therefore, the forklift 100 can select whether to use the corrected relationship data Dc or the learned relationship data De for the knob misalignment correcting operation. In the following knob deviation correcting operation, an example of using the corrected relationship data Dc will be shown. It can be applied when

(Knob misalignment correction operation)
The knob deviation correcting operation will be described. As described above, the knob deviation correcting operation obtains the target steering wheel angle Hc corresponding to the acquired tire angle Tg based on the post-correction relationship data Dc, and operates the solenoid valve 44 so that the acquired steering wheel angle Hg approaches the target steering wheel angle Hc. is the operation that controls the In the knob deviation correction operation of this embodiment, the knob deviation is corrected so that the knob 12b of the steering wheel 12 is positioned at the 8 o'clock position when the steered wheels 14 are in the straight-ahead position.

An example of the knob deviation correcting operation will be described with reference to FIG. 13 . FIG. 13 is a flow chart showing an example of the knob misalignment correcting operation of this embodiment, and shows the processing S110 related to this operation. The acquisition operation process S110 is always executed while the forklift 100 is in operation. The process may be stopped while the steering wheel is not operated and the steering wheel angle is not changed. Therefore, the process S110 is started when the forklift 100 starts operating.

In step S110, the knob displacement correcting operation is performed at predetermined time intervals Tp (for example, 10 ms).
When the process S110 is started, the control unit 30 resets the timer that manages the predetermined time Tp to start time counting (hereinafter referred to as time measurement) (step S111).

After step S111 is completed, the control unit 30 reads the obtained steering wheel angle Hg and the obtained tire angle Tg (step S112). After acquiring the acquired tire angle Tg, the control unit 30 obtains the target steering wheel angle Hc corresponding to the acquired tire angle Tg from the post-correction relationship data Dc (step S113).

After determining the target steering wheel angle Hc, the controller 30 opens the solenoid valve 44 according to the difference between the obtained steering wheel angle Hg and the target steering wheel angle Hc (step S114). By opening the solenoid valve 44, the hydraulic oil supplied to the steering cylinder 48 is reduced, causing idling in the operation of the steering wheel 12 and correcting the knob 12b to the normal position. In this step, the solenoid valve 44 may be opened according to the time corresponding to the difference in steering wheel angle or the duty ratio corresponding to the difference in steering wheel angle.

After step S114 is completed, the control unit 30 determines whether or not the timer has exceeded the predetermined time Tp (step S115). If the measured time has not exceeded the predetermined time Tp (N in step S115), the control unit 30 returns the process to the beginning of step S115, and repeats step S115. If the measured time exceeds the predetermined time Tp (Y in step S115), the control unit 30 returns the process to the beginning of step S111, and repeats the processes of steps S111 to S115. These processes are merely examples, and other steps may be added, some steps may be changed or deleted, and the order of steps may be changed.

(hydraulic pressure reduction operation)
As described above, the hydraulic pressure reduction operation is an operation of reducing the hydraulic pressure of the hydraulic device that steers the steered wheels when the tire angle of the steered wheels reaches a predetermined angle, and is controlled by the hydraulic pressure reduction section 30p. The hydraulic pressure reduction operation of the present embodiment reduces the hydraulic pressure supplied to the steering cylinder 48 when the obtained tire angle Tg of the steered wheels 14 approaches both ends. In the present embodiment, a predetermined tire angle Ta is set in advance in the hydraulic pressure reducing portion 30p. The predetermined angle Ta may be set in the range of 5° to 15° before both ends.

When the obtained tire angle Tg exceeds the predetermined angle Ta and approaches both ends, the control unit 30 gradually decreases the rotational speed of the cargo handling motor 60m to gradually decrease the delivery pressure of the hydraulic pump 50 . Furthermore, when the obtained tire angle Tg reaches near the end, the control unit 30 controls the cargo handling motor 60m to stop rotating. In this case, it is desirable not to change the hydraulic pressure of the hydraulic oil delivered to the lifting cylinder 66 so as not to affect the operation of the cargo handling section 60 . As an example, a hydraulic check valve may be provided in the middle of line 66a. By including the hydraulic pressure reduction operation, it is possible to suppress the deviation of the steering wheel angle due to the steering wheel hitting the end and the noise oil leaking.

The above has been described based on the embodiments of the present invention. Those skilled in the art will appreciate that these embodiments are illustrative, and that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes also fall within the scope of the claims of the present invention. It is understood. Accordingly, the description and drawings herein are to be regarded in an illustrative rather than a restrictive sense.

Modifications will be described below. In the drawings and description of the modified example, the same reference numerals are given to the same or equivalent components and members as the embodiment. Descriptions that overlap with the embodiment will be omitted as appropriate, and the configuration that is different from the first embodiment will be mainly described.

[Modification]
Although the forklift 100 is a so-called counterbalance forklift in the description of the embodiment, the present invention is not limited to this. The forklift 100 may be another type of forklift, such as a reach-type forklift.

In the description of the embodiment, an example of a so-called weight reduction method in which the steering wheel 12 is idly rotated for correction has been shown, but the present invention is not limited to this. For example, it may be a so-called increase method that corrects by increasing the flow rate of the hydraulic oil to the steering cylinder by a bypass circuit, or a correction method that uses both the decrease method and the increase method and has both functions. may

In the description of the embodiment, the correction operation for obtaining the post-correction relationship data Dc from the initial relationship data Dm in accordance with the correction data Dj has been shown as an example in which the forklift 100 is always in operation. is not limited to When the post-correction relationship data Dc is acquired, the initial relationship data Dm may be rewritten and updated by the post-correction relationship data Dc.

In the description of the embodiment, an example in which the hydraulic pump 50 is driven by the cargo handling motor 60m was shown, but the present invention is not limited to this. The hydraulic pump 50 may be driven by a prime mover based on principles other than an electric motor. For example, the hydraulic pump 50 may be driven by an engine, in which case this engine may be the engine for driving the forklift 100 .

In the description of the embodiment, the steering wheel angle sensor 34 is an optical rotary encoder and the tire angle sensor 36 is a potentiometer, but the present invention is not limited to this. For example, the steering wheel angle sensor 34 may be a rotation sensor based on the principle of electromagnetic induction, such as a resolver.

In the description of the embodiment, an example in which the control unit 30 has the relationship learning unit 30f, the predetermined value setting unit 30h, and the hydraulic pressure reducing unit 30p is shown, but the present invention is not limited to this. Providing these is not essential, and the control unit 30 may not have some or all of them.

Although the steering wheel 12 is an annular steering wheel in the description of the embodiment, the present invention is not limited to this. The handle 12 may be of any type as long as it can be manually operated by the operator, and may be, for example, a bar-shaped one.

Each of the modifications described above has the same actions and effects as the embodiment.

Any combination of the above-described embodiments and modifications is also useful as embodiments of the present invention. A new embodiment resulting from the combination has the effects of each of the combined embodiments and modifications.

Reference Signs List 10 Steering mechanism 12 Steering wheel 12b Knob 14 Steering wheel 28 Drive mechanism 30 Control unit 32 Setting input unit 34 Steering wheel angle sensor 36 Tire angle sensor 40 Hydraulic mechanism 42 Steering valve unit 44 Solenoid valve 48 Steering cylinder 100 Forklift.

Claims (5)

A forklift having a power steering device equipped with a hydraulic device for steering wheels according to rotation of a steering wheel,
a steering wheel angle sensor that provides a first detection result according to the steering wheel angle of the steering wheel;
a tire angle sensor that provides a second detection result according to the tire angle of the steered wheels;
storage means for storing an initial relationship between the steering wheel angle and the tire angle in the steering angle range of the steered wheels;
Acquisition means for acquiring the first detection result and the second detection result at the straight position, the first measurement position and the second measurement position of the steering wheel;
correction means for correcting the initial relationship stored in the storage means based on the acquisition result of the acquisition means and obtaining post-correction relationship data;
a control unit that controls the hydraulic device based on the corrected relationship data;
The first measurement position is set to a position between the straight-ahead position and the maximum steering angle position and not including the maximum steering angle position,
The second measurement position is set to a position between the straight-ahead position and the minimum steering angle position and not including the minimum steering angle position,
The first measurement position and the second measurement position are set 10% to 30% of the steering angle range before the maximum steering angle position and the minimum steering angle position,
The acquisition means acquires the first detection result and the second detection result at the straight-ahead position when receiving an instruction from the operator as the straight-ahead position, and acquires the first detection result and the second detection result at the straight-ahead position when receiving an instruction from the operator as the first measurement position. The first detection result and the second detection result at the first measurement position are acquired, and the first detection result and the second detection result at the second measurement position are received when an instruction is received from the operator as the second measurement position . A forklift characterized by acquiring a detection result. 2. The forklift truck according to claim 1, further comprising a display unit for displaying that the tire angle of the steered wheels exceeds a threshold when the tire angle exceeds the threshold. 3. The forklift truck according to claim 1, wherein when the tire angle of the steering wheel exceeds a threshold value, the first detection result and the second detection result are not acquired. 4. The forklift according to claim 1, wherein the hydraulic pressure of the hydraulic device is lowered when the steering angle of the steered wheels reaches a predetermined angle. The present forklift stores the first detection result and the second detection result as learned relationship data for each predetermined angle according to the steering wheel operation of the operator,
When setting is made to select the learned relationship data from the corrected relationship data and the learned relationship data, the control unit selects the learned relationship data instead of the corrected relationship data. 5. A forklift according to any one of claims 1 to 4, wherein the hydraulic system is controlled using a hydraulic system.

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