JP2019166869A - Fork lift - Google Patents

Abstract

To provide a fork lift capable of easily finding abnormality in detecting means for handle operation.SOLUTION: A fork lift includes: a handle 12; a steering mechanism 50 that turns a direction of wheels in accordance with operation to the handle 12; an assist mechanism 26 that generates assist force for assisting the steering mechanism 50; detecting means for detecting that no operation is given to the handle 12; and determining means 10 for determining that there is abnormality when the assist mechanism 26 generates the assist force with the handle 12 being not operated.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a forklift.

  For example, Patent Document 1 describes a forklift failure diagnosis device having a cargo handling attachment. The forklift failure diagnosis device described in Patent Literature 1 detects a failure that is fixed when the cargo handling operation detection means is in an on state.

JP-A-10-329744

The present inventor has obtained the following recognition regarding a forklift provided with a power steering mechanism that assists the driver's steering. The power steering mechanism detects the steering force of the driver's steering wheel, and generates an auxiliary force for assisting steering based on the detection result. If the detection means for detecting the handle operation is abnormal, an erroneous detection result is output from there. In this case, it is conceivable that unnecessary auxiliary force is generated even though the handle is not operated. When the abnormality of the detection means is remarkable, the steering characteristic changes greatly, so that the detection is easy. However, when the abnormality is not remarkable, the characteristic change is small and the detection becomes difficult. In this case, since the power steering mechanism continues to generate a weak assist force even when it is not operated, there is a problem in that excessive heat generation and stress are applied to the component parts and the life is shortened.
From this, the present inventor has recognized that there is room for improvement in the forklift from the viewpoint of facilitating discovery of abnormality in the detection means of the handle operation.

  An object of the present invention is to provide a forklift that can easily detect an abnormality in a detection means for a handle operation.

  In order to solve the above problems, a forklift according to an aspect of the present invention includes a handle, a steering mechanism that steers the direction of the wheel in accordance with the operation of the handle, an assist mechanism that generates an assist force that assists the steering mechanism, A forklift equipped with a detecting means for detecting that the handle is not operated, and when the assist mechanism is generating an assisting force when the handle is not operated, it is determined to be abnormal Determining means.

  According to this aspect, it can be determined that there is an abnormality when assisting force is generated in a state where the steering wheel is not operated.

  Note that any combination of the above-described constituent elements, and those obtained by replacing the constituent elements and expressions of the present invention with each other between methods and systems are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the forklift which can discover abnormality of the detection means of a handle operation easily can be provided.

It is a perspective view which shows an example of the forklift which concerns on 1st Embodiment. It is a block diagram which shows an example of a structure of the forklift truck 100 of FIG. It is a block diagram which shows an example of a structure of the steering mechanism of the forklift of FIG. It is a block diagram which shows an example of a structure of the operation amount detection part of the forklift of FIG. It is an enlarged view which expands and shows a part of operation amount detection part of FIG. It is a time chart which shows the relationship between the operation amount of the handle | steering-wheel of the forklift of FIG. 1, and auxiliary force.

The present invention will be described below based on preferred embodiments with reference to the drawings. In the embodiment and the modification, the same or equivalent components and members are denoted by the same reference numerals, and repeated description is appropriately omitted. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in the drawings, some of the members that are not important for describing the embodiment are omitted.
In addition, terms including ordinal numbers such as first and second are used to describe various components, but this term is used only for the purpose of distinguishing one component from other components. However, the constituent elements are not limited.

  In the following description, “parallel” and “vertical” include not only perfect parallel and vertical, but also include cases in which they deviate from parallel and vertical within an error range. Further, “substantially” means that they are the same in an approximate range.

[Embodiment]
First, an overall configuration of a forklift 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view schematically showing a forklift 100. FIG. 2 is a block diagram showing the configuration of the forklift 100. As shown in FIG. 1, the travel direction of the forklift 100 is “front side”, “rear side”, the vehicle width direction is “right side”, “left side”, and the vehicle height direction is “upper side”, “lower side”. There is. Such notation of direction does not limit the use posture of the forklift 100, 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 reach-type forklift that can move a mast for cargo handling back and forth. Forklift 100 mainly includes a vehicle body 20 and a cargo handling unit 60.

(Handling Department)
The cargo handling unit 60 is provided in a front portion of the vehicle body 20. The cargo handling unit 60 includes a fork 62, a mast 64, an elevating cylinder (not shown), and a reach cylinder (not shown). The fork 62 is inserted into the fork pocket (insertion hole) of the pallet on which the load is placed. The mast 64 supports the fork 62 so as to be movable up and down. The elevating cylinder is a hydraulic cylinder for moving the fork 62 up and down along the mast 64. The reach cylinder is a hydraulic cylinder for moving the fork 62 and the mast 64 in the front-rear direction.

(Body)
The vehicle body 20 includes a boarding space 24, a front wheel 16, a control unit 30, a drive mechanism 28, a steering mechanism 50, and a hydraulic mechanism 58. The boarding space 24 is a place where the driver gets on the forklift 100 and operates the forklift 100 in a standing posture. The boarding space 24 may be a driver seat having a seat on which a driver can sit. An operation unit 18 having a lever for controlling the operation of the cargo handling unit 60 is provided in front of the boarding space 24. A brake pedal (not shown) is provided on the floor of the boarding space 24. When the driver removes his / her foot from the brake pedal, the brake mechanism (not shown) operates to stop the forklift 100 from traveling. This brake mechanism is sometimes referred to as a deadman brake.

  As shown in FIG. 1, the front wheels 16 are a pair of wheels that are spaced apart from each other at the front end of the outrigger 16 b. The front wheel 16 of the present embodiment is an idler wheel whose direction with respect to the vehicle body 20 is fixed. The control unit 30 mainly controls the drive mechanism 28, the steering mechanism 50, the hydraulic mechanism 58, and the cargo handling unit 60 based on the operation of the driver. The control unit 30 will be described later.

(Drive mechanism)
The drive mechanism 28 drives the forklift 100 by rotating the steering wheel 14 by the motor 28m. The drive mechanism 28 is disposed at a position adjacent to the boarding space 24 on the rear side of the vehicle body 20. The drive mechanism 28 of the present embodiment includes a motor 28m and a first drive circuit 28c. The motor 28m is a prime mover that causes the forklift 100 to travel by driving the steering wheel 14 to rotate. The motor 28m is rotated by the electric power supplied from the battery 28b, and drives the steered wheels 14 according to the control of the control unit 30. The first drive circuit 28 c is a circuit that drives the motor 28 m based on the control of the control unit 30. The drive mechanism 28 may include a gear device for transmitting the rotation of the motor 28m to the steered wheels 14 by decelerating or increasing the speed.

  The hydraulic mechanism 58 includes a hydraulic pump (not shown), an oil tank (not shown), and the like, and mainly supplies pressurized oil to a cylinder such as a lifting cylinder or a reach cylinder of the cargo handling unit 60.

(Steering mechanism)
Next, the steering mechanism 50 will be described with reference to FIGS. FIG. 3 is a configuration diagram illustrating an example of the configuration of the steering mechanism 50. The steering mechanism 50 steers the direction of the steered wheels 14 exemplified as wheels in accordance with the operation of the handle 12. In particular, the steering mechanism 50 steers the steering wheel 14 in accordance with the operation amount of the handle 12 and turns the forklift 100. The steering mechanism 50 of the present embodiment includes the handle 12, the steering wheel 14, the steering transmission mechanism 54, the steering wheel support portion 52, and the assist mechanism 26.

(handle)
The handle 12 is configured to be able to steer the steered wheel 14 by an operation of the driver, and has a handle 12b that can be used by the driver to operate the handle. In the present embodiment, when the handle 12 is rotated a plurality of times (for example, seven times), the steering angle of the steered wheels 14 changes to the maximum range (for example, 270 °). The handle 12 of this embodiment is an annular steering wheel.

(Steering wheel)
The steering wheel 14 is rotated by the steering mechanism 50 to turn the forklift 100. The steered wheel 14 is also a drive wheel that applies a driving force for traveling the forklift 100 to the road surface. As shown in FIG. 1, the steering wheel 14 is provided on the left rear side of the vehicle body 20.

(Steering wheel support)
The steering wheel support portion 52 supports the steering wheel 14 and is supported by the vehicle body 20 in a rotatable state. The steering wheel support portion 52 is provided with a steering gear 52g surrounding the steering wheel support portion 52 in the rotation direction.

(Steering transmission mechanism)
The steering transmission mechanism 54 transmits the steering torque of the handle 12 to the steering wheel 14 to steer the steering wheel 14. The steering transmission mechanism 54 includes a rod-shaped shaft member 54 b extending from the handle 12 toward the steering wheel support portion 52. A transmission gear 54g that meshes with the steering gear 52g is provided at the lower end of the shaft member 54b. The steering torque of the handle 12 is transmitted to the steering wheel support 52 via the transmission gear 54g and the steering gear 52g, and rotates the steering wheel 14 supported by the steering wheel support 52.

(Assist mechanism)
The assist mechanism 26 generates an assist force that assists the steering mechanism 50. The assist mechanism 26 of the present embodiment includes an operation amount detection unit 40, a handle operation detection unit 34, an assist motor 26m, a second drive circuit 26c, and a control unit 30. In the present embodiment, the control unit 30, the handle operation detection unit 34, and the operation amount detection unit 40 constitute a determination unit 10 described later.

  The operation amount detection unit 40 detects the operation amount of the handle 12 and outputs the detection result as an output voltage. The operation amount detection unit 40 will be described later. The handle operation detection unit 34 is detection means for detecting that the handle 12 is not operated. The control unit 30 includes an abnormality determination unit 30j that determines that there is an abnormality when the assist mechanism 26 generates an assisting force when the handle 12 is not operated.

(Handle operation detector)
The steering wheel operation detection unit 34 of the present embodiment is a driver detection sensor 34h that detects that there is no driver in the boarding space 24. When there is no driver in the boarding space 24, it can be determined that the steering wheel 12 is not operated.

(Driver detection sensor)
The driver detection sensor 34h of the present embodiment is a load sensor that detects the presence of the driver based on the load of the boarding space 24. That is, the driver detection sensor 34h detects the load applied to the boarding space 24 when the driver is on board and when the driver is not boarding, and detects the presence of the driver from the difference. The load sensor may be provided on the floor of the boarding space 24. The driver detection sensor 34h may include a sensor that detects the presence of the driver based on a principle different from that of the load sensor, such as an infrared sensor or an image sensor.

(Assist motor)
The assist motor 26m assists the steering of the steered wheel 14 by the handle 12. The assist motor 26m is a so-called electric power steering (EPS) motor. The assist motor 26m is rotated by electric power supplied from the battery 28b. The assist motor 26m generates an assist force according to the operation amount of the handle 12 transmitted by the steering transmission mechanism 54, and assists the steering of the steered wheel support portion 52 and the steered wheel 14 by the assist force. An assist gear 26g that meshes with the steering gear 52g is provided on the output shaft of the assist motor 26m. The assisting force of the assist motor 26m is transmitted to the steering wheel support portion 52 via the assist gear 26g and the steering gear 52g, and rotates the steering wheel 14 supported by the steering wheel support portion 52. The second drive circuit 26 c is a circuit that drives the assist motor 26 m based on the control of the control unit 30.

(Control part)
Next, the control unit 30 will be described with reference to FIG. Each block of the control unit 30 shown in FIG. 2 can be realized in hardware by an element and a mechanical device such as a CPU (Central Processing Unit) of a computer, and in software by a computer program or the like. However, here, functional blocks realized by their cooperation are depicted. Therefore, it is understood by those skilled in the art who have touched this specification that these functional blocks can be realized in various forms by a combination of hardware and software.

  The control unit 30 includes an operation result acquisition unit 30a, an operation amount acquisition unit 30b, an operation detection result acquisition unit 30c, a travel control unit 30f, a steering control unit 30g, a hydraulic control unit 30h, and an abnormality determination unit 30j. ,including. The operation result acquisition unit 30 a acquires an operation result from the operation unit 18. The operation amount acquisition unit 30 b acquires the operation amount of the handle 12 from the operation amount detection unit 40. In this example, the operation amount acquisition unit 30b acquires an output voltage of a potentiometer 42 described later.

  The operation detection result acquisition unit 30c acquires the detection result of the driver detection sensor 34h of the handle operation detection unit 34. The travel control unit 30f controls the rotation of the motor 28m via the first drive circuit 28c. The steering control unit 30g controls the rotation of the assist motor 26m via the second drive circuit 26c. The hydraulic control unit 30 h controls the hydraulic mechanism 58. The abnormality determination unit 30j determines whether or not the operation amount detection unit 40 is abnormal, and controls the notification unit 32 based on the result.

(Operation amount detector)
Next, the operation amount detection unit 40 will be described with reference to FIGS. 4 and 5. FIG. 4 is a configuration diagram illustrating an example of the configuration of the operation amount detection unit 40. FIG. 5 is an enlarged view showing a part of the operation amount detection unit 40 of FIG. The operation amount detection unit 40 is not particularly limited as long as it can detect the operation amount of the handle 12. The operation amount detector 40 of the present embodiment includes a shaft member 54b, a drive gear 36b, a driven gear 38b, a rotating body 44, a rotating body support 48, an arm 46, and a potentiometer 42. .

  As described above, the shaft member 54b is a rod-shaped member extending from the handle 12 toward the steering wheel support portion 52, and rotates integrally with the handle 12 when the handle 12 is rotated. The drive gear 36b is a spur gear provided on the shaft member 54b so as to rotate integrally with the shaft member 54b. The driven gear 38b is a spur gear that meshes with the drive gear 36b and rotates based on the rotation of the shaft member 54b. The drive gear 36b and the driven gear 38b are rotatably supported by bearing means (not shown).

  The rotating body 44 is a member that is rotatably supported around a rotation axis that is common to the driven gear 38b. The rotating body 44 contacts the driven gear 38b and rotates as the driven gear 38b rotates. The rotating body 44 includes a substantially circular base portion 44b that contacts the driven gear 38b, and two leg portions 44c and 44d that extend outward in the radial direction from the outer periphery of the base portion 44b. The first leg portion 44c and the second leg portion 44d are arranged at a predetermined angle in the circumferential direction. In this example, this angle is set to approximately 90 °.

  The rotating body support portion 48 is a support mechanism that supports the rotating position of the rotating body 44 so as to maintain a predetermined reference position (hereinafter referred to as a neutral position). When the rotator 44 rotates in association with the driven gear 38b, the rotator support 48 functions to apply a biasing force in the opposite direction to the rotation, and return the rotator 44 to the neutral position. In this example, the rotator support 48 includes a first support 48a that applies a biasing force in the direction of arrow R (hereinafter referred to as “clockwise”) to the first leg 44c, and an arrow L to the second leg 44d. And a second support portion 48b for applying a biasing force in a direction (hereinafter referred to as “counterclockwise”). In this example, the support portions 48a and 48b are coil springs. One end of each of the support portions 48a and 48b is fixed, and the other end is disposed so as to apply a biasing force to the leg portions 44c and 44d. The support portions 48a and 48b extend at an angle of approximately 90 ° in the extending direction of the leg portions 44c and 44d. The neutral position of the rotating body 44 is a position where the urging forces of the support portions 48a and 48b are balanced.

  The rotating body 44 once rotates in synchronization with the rotation of the driven gear 38b. When the rotation of the driven gear 38b stops, the rotating body support portion 48 returns the rotating body 44 to the neutral position. That is, the rotating body 44 rotates to a position deviated from the neutral position while the handle 12 is operated, and the rotating body 44 returns to the neutral position when the handle 12 is not operated.

  The arm 46 is a link member that rotates the potentiometer 42 according to the rotation of the rotating body 44. That is, the arm 46 moves in accordance with the operation of the handle 12 and rotates the potentiometer 42. The arm 46 of the present embodiment is a rod-shaped member that extends outward in the radial direction from the outer periphery of the base portion 44 b and moves integrally with the rotating body 44. Although the arm 46 may be formed separately from the rotating body 44, the arm 46 in this example is a member integrated with the rotating body 44. The arm 46 is disposed at a position about 45 ° away from the leg 44c of the leg 44d in the circumferential direction.

  The potentiometer 42 includes an input shaft 42a disposed at the center of the main body, a moving body 42b extending radially outward from the input shaft 42a, a biasing member 42s for pressing the moving body 42b against the arm 46, and an output signal. A transmission cable 42c. The input shaft 42 a extends in parallel with the rotation axis of the rotating body 44. The potentiometer 42 detects a voltage according to the rotation of the input shaft 42a and transmits the detection result to the control unit 30 via the cable 42c. The moving body 42b is linked to the arm 46, moves with the arm 46, and rotates the input shaft 42a. The potentiometer 42 outputs a signal indicating the amount of movement of the moving body 42b. Specifically, the potentiometer 42 outputs an output voltage corresponding to the moving amount of the moving body 42b. The moving body 42b has a protrusion 42p in the vicinity of the extending end of the moving body 42b. The protrusion 42 p extends toward the arm 46 and is linked to the arm 46.

  The arm 46 has a housing recess 46g for housing the protrusion 42p. The housing recess 46g is provided on the surface of the arm 46 that faces the moving body 42b. The arm 46 has a first surface 46h and a second surface 46j in the housing recess 46g. The first surface 46h and the second surface 46j oppose each other with the protrusion 42p interposed therebetween. The first surface 46h and the second surface 46j are arranged at a predetermined interval from each other.

  The biasing member 42s is a member that applies a biasing force in a predetermined rotational direction to the input shaft 42a. As shown in FIG. 4, the biasing member 42s of the present embodiment applies a counterclockwise biasing force to the input shaft 42a when viewed from the protruding side of the input shaft 42a. Due to this urging force, the moving body 42b receives a counterclockwise urging force, so that the protrusion 42p contacts the first surface 46h located on the counterclockwise side of the protrusion 42p. Alternatively, the moving body 42b may be urged clockwise to bring the protrusion 42p into contact with the second surface 46j.

  When the rotating body 44 rotates clockwise, the protrusion 42p is pushed by the first surface 46h, and rotates the input shaft 42a clockwise. Even when the rotating body 44 rotates counterclockwise, the protrusion 42p maintains the state of contacting the first surface 46h by the biasing force of the biasing member 42s.

  Next, the operation of the assist mechanism 26 configured as described above will be described. FIG. 6 is a time chart showing an example of the operation amount Mv of the handle 12 and the assisting force Ap of the assist motor 26m. This figure shows the transition of the operation amount Mv and the assisting force Ap with the horizontal axis as the elapsed time.

  In FIG. 6, Mv indicates the transition of the operation amount Mv of the handle 12. Mv indicates an operation amount in which the neutral position of the handle 12 is zero, the plus side is clockwise, and the minus side is counterclockwise. Initially, the handle 12 is in the neutral position, and the handle 12 is operated clockwise in the period T1, and the handle operation is stopped at that position in the period T2. In the period T3, the handle 12 is operated counterclockwise to return to the neutral position, and in the period T4, the handle operation is stopped at that position. In the period T5, the handle 12 is operated counterclockwise, and in the period T6, the handle operation is stopped at that position. In the period T7, the handle 12 is operated clockwise to return to the neutral position, and in the period T8, the handle operation is stopped at that position.

  In FIG. 6, P1 and P2 indicate changes in the relative position of the protrusion 42p between the first surface 46h and the second surface 46j. P1 shows a case where the urging member 42s functions normally, and P2 shows an abnormal case where the urging member 42s does not function.

  First, P1 in a normal case will be described. Initially, the protrusion 42p is in contact with the first surface 46h, and during the periods T1 and T2, the protrusion 42p moves while being in contact with the first surface 46h. In the period T3, during the operation of the handle 12, the protrusion 42p moves while being in contact with the first surface 46h by the urging force of the urging member 42s. After the operation of the handle 12 is stopped, in the period T4, the protrusion 42p maintains a state in contact with the first surface 46h.

  In the period T5, during the operation of the handle 12, the protrusion 42p moves while being in contact with the first surface 46h by the urging force of the urging member 42s. After the operation of the handle 12 is stopped, in a period T6, the protrusion 42p maintains a state in contact with the first surface 46h. Even in the periods T7 and T8, the protrusion 42p moves while being in contact with the first surface 46h.

  That is, in the periods T1, T3, T5, and T7 during which the handle 12 is operated, the protrusion 42p moves while being in contact with the first surface 46h by the urging force of the urging member 42s. Further, in the periods T2, T4, T6, and T8 during which the operation of the handle 12 is stopped, the protrusion 42p maintains a state in contact with the first surface 46h.

  In FIG. 6, Ap indicates the transition of the assisting force Ap of the assist motor 26m. In this embodiment, when the operation of the handle 12 is stopped, in order to set the auxiliary force to zero, as in the periods T2, T4, T6, and T8, when the protrusion 42p is in the neutral position in contact with the first surface 46h. The output voltage of the potentiometer 42 is used as a reference voltage. Further, the assist mechanism 26 generates an auxiliary force Ap clockwise (plus side in FIG. 6) when the output voltage of the potentiometer 42 is higher than the reference voltage, and counterclockwise (minus side in FIG. 6) when the output voltage is low. ) Assisting force Ap is generated.

  In addition, in order to avoid the influence of manufacturing errors, changes with time, etc., a dead band having a predetermined width is provided above and below the reference voltage, and the range where the auxiliary force Ap is zero is expanded. That is, the assist mechanism 26 generates the assist force Ap when a voltage of a predetermined value or more is output from the potentiometer 42 from the reference voltage when the moving body 42b is in the neutral position. As a result, as shown by the solid line Ap in FIG. 6, the auxiliary force Ap is generated in the periods T1, T3, T5, and T7 in which the handle 12 is operated, and the periods T2, T4, and T6 in which the handle 12 is not operated. , No auxiliary force Ap is generated at T8.

  Based on this operation, P2 in an abnormal case will be described. In P2, it operates in the same manner as P1 in the periods T1 and T7 in which the steering wheel is operated clockwise, and in the periods T4 and T6, it moves to the same position as P1 along with the movement. Further, in P2, since the urging force of the urging member 42s does not act, in the periods T2, T3, T5, and T8, the protrusion 42p is separated from the first surface 46h and located on the second surface 46j side, and the periods T4, At T6, the protrusion 42p moves from the second surface 46j to the first surface 46h. As a result, as shown by the broken line Ap in FIG. 6, the output voltage exceeds the dead band of the reference voltage and the slight assist force Ap is generated even in the periods T2 and T8 when the handle 12 is not operated. In addition, during the periods T3 and T5 during which the handle 12 is operated, the position of the protrusion 42p is deviated from the normal time, so that a smaller assist force Ap is generated than in the normal time. Even if a slight assisting force Ap is generated when the handle 12 is not operated, there is no noticeable symptom, so it is difficult to know this state. If a small assist force Ap is generated, unintended steering may occur during traveling, and a weak current always flows, and the assist motor 26m generates heat, which may shorten the life. In addition, when the steering wheel is neutral, other work is performed and the steering wheel operation is performed again, unintended steering may occur.

  For this reason, this embodiment has the determination means 10 which determines with it being abnormal, when the assist mechanism 26 is producing | generating the auxiliary force Ap in the state in which the handle | steering wheel 12 is not operated (FIG. 2, FIG. 3). See also). The determination unit 10 of the present embodiment includes a control unit 30, an operation amount detection unit 40, and a handle operation detection unit 34 (driver detection sensor 34h). The determination result of the determination unit 10 is output from the abnormality determination unit 30j of the control unit 30.

  In FIG. 6, Sa shows the detection result of the driver detection sensor 34h. When the driver detection sensor 34h detects the driver, Sa is at the L level, and when not detected, Sa is at the H level.

  In FIG. 6, Sb is a determination result of the determination means 10, and specifically indicates an output signal of the abnormality determination unit 30j. The determination means 10 determines that the abnormality is detected when the assisting force Ap is generated (Ap is not zero) in a state where the driver detection sensor 34h does not detect the driver (Sa is H level). . Sb in FIG. 6 is at the H level when it is determined to be abnormal, and at the L level in other cases. As shown in FIG. 6, when the assisting force Ap is not zero as shown by the broken line Ap during the non-operation period of the handle 12, the determining means 10 determines that there is an abnormality and Sb becomes H level.

  When the determination means 10 determines that there is an abnormality, it is desirable to notify the driver of the determination result. For this reason, this embodiment has the alerting | reporting part 32 which alert | reports the determination result of the determination means 10. FIG. The notification unit 32 of the present embodiment outputs a notification sound by a sound output device such as a buzzer when Sb is at the H level. In this case, since the driver can recognize the abnormality by the notification sound, it is possible to take appropriate measures such as repair and inspection.

  Even when the biasing member 42s is in a normal state, the driver detection sensor 34h may not detect the driver in a short time before the protrusion 42p returns to the first surface 46h. In this case, the determination means 10 erroneously determines that there is an abnormality, and a notification sound is output. If the notification sound is frequently output, it is troublesome for the driver. Therefore, the determination unit 10 according to the present embodiment determines that the abnormality is detected when the state in which the assist mechanism 26 generates the auxiliary force Ap continues for a predetermined time Pd in a state where the handle 12 is not operated. To do. In this case, the possibility of erroneous determination can be reduced. The time Pd can be set by experiment corresponding to a desired characteristic. This operation is executed by the control unit 30.

  Further, the control unit 30 controls the assist force Ap to be zero when the assist mechanism 26 is generating the assist force Ap for a predetermined time Pd when the handle 12 is not operated. May be.

  In the above, it demonstrated based on embodiment of this invention. It is to be understood by those skilled in the art 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 are also within the scope of the claims of the present invention. It is understood. Accordingly, the description and drawings herein are to be regarded as illustrative rather than restrictive.

  Hereinafter, modified examples will be described. In the drawings and description of the modification, the same reference numerals are given to the same or equivalent components and members as those in the embodiment. The description which overlaps with embodiment is abbreviate | omitted suitably, and demonstrates a structure different from 1st Embodiment mainly.

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

  In the description of the embodiment, an example in which the steered wheels 14 also serve as drive wheels has been shown, but the present invention is not limited to this. In addition to the steered wheels 14, drive wheels for running a forklift may be provided.

  In the description of the embodiment, an example in which the handle operation detection unit 34 is the driver detection sensor 34h is shown, but the present invention is not limited to this. The handle operation detection unit 34 is only required to detect that the handle 12 is not operated. For example, the handle operation detection unit 34 may be a touch sensor provided on the handle 12, or steering applied to the handle 12. A torque sensor that detects force may be used.

  In the description of the embodiment, the example in which the steering mechanism 50 includes the potentiometer 42 that detects the operation amount of the handle 12 has been described, but the present invention is not limited to this. The steering mechanism 50 may include a rotation sensor such as a torque sensor that detects an operation torque of the handle 12 or a rotary encoder that outputs a pulse corresponding to the rotation of the handle 12 instead of the potentiometer 42.

  In the description of the embodiment, an example in which the steering mechanism 50 includes the assist motor 26m that is electrically driven is shown, but the present invention is not limited to this. The steering mechanism may include auxiliary force generation means based on another principle, such as a hydraulic motor that generates auxiliary force by hydraulic pressure, instead of the assist motor 26m.

  In the description of the embodiment, the example in which the notification unit 32 outputs the notification sound by the audio output device has been described, but the present invention is not limited to this. The alerting | reporting part 32 may show a determination result with light or an image | video, and may transmit a case result to another electronic terminal through a network.

  In the description of the embodiment, an example in which the handle 12 is an annular steering wheel is shown, but the present invention is not limited to this. The handle 12 may be anything that can be manually operated by the driver, and may be, for example, a rod-like one.

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

  Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. The new embodiment generated by the combination has the effects of the combined embodiments and modifications.

  10 .... determining means, 12 .... steering wheel, 14 .... steering wheel, 20 .... body, 24 .... boarding space, 26..assist mechanism, 26c..second drive circuit, 26m..assist motor, 28.・ Drive mechanism 30 ・ ・ Control unit 30j ・ Abnormality judgment unit 34 ・ ・ Handle operation detection unit 40 ・ ・ Operation amount detection unit 42 ・ ・ Potentiometer 42b ・ ・ Moving body 42p ・ ・ Projection 42s ..Biasing member 44..Rotating body 46..Arm 46h..First surface 46j..Second surface 48..Rotating body support 50. Steering mechanism 54. Steering transmission Mechanism, 100. Forklift.

Claims (8)

A forklift comprising a steering wheel, a steering mechanism that steers the direction of a wheel according to the operation of the steering wheel, and an assist mechanism that generates an auxiliary force that assists the steering mechanism,
Detecting means for detecting that the handle is not operated;
A determination unit that determines that the assist mechanism is abnormal when the assist mechanism is generating an assist force in a state where the handle is not operated;
Forklift characterized by having.   The forklift according to claim 1, wherein the detection means detects that there is no driver in the boarding space.   The forklift according to claim 1, wherein the assist mechanism includes a potentiometer that detects an operation amount of the handle. The assist mechanism has an arm that moves according to the operation of the handle,
The potentiometer has a moving body that moves with the arm,
The forklift according to claim 3, wherein the potentiometer outputs a signal indicating a movement amount of the moving body. The potentiometer outputs a voltage corresponding to the moving amount of the moving body,
The assist mechanism generates the assist force when a voltage of a predetermined value or more is output from a reference voltage when the moving body is in a neutral position,
5. The forklift according to claim 4, wherein the determination unit determines that there is an abnormality when a voltage equal to or higher than the predetermined value is output in a state where the handle is not operated.   The forklift according to claim 4, wherein the potentiometer includes a biasing member that presses the moving body against the arm. The arm has a first surface and a second surface;
The movable body is disposed between the first surface and the second surface;
The forklift according to claim 6, wherein the moving body is pressed against the first surface.   2. The determination unit according to claim 1, wherein the determination unit determines that there is an abnormality when a state in which the assist mechanism generates an assisting force continues for a predetermined time in a state where the handle is not operated. The forklift according to any one of 7 above.

Images