JP2013052965A - Carrier vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrier vehicle of higher running stability which carries workpieces.SOLUTION: A load detector which detects the load added to front wheels 10 and rear wheels 6 is arranged on the front wheels 10 and the rear wheels 6 of a clamp lift 1. After the clamp lift 1 clamps the workpieces W, a control device 4 detects the load added to the front wheels 10 and the rear wheels 6 to compute the target loads N1 and N2 so that run resistance in each wheel may become equal. Next, a mast 16 is tilted back and forth and makes a clamp bracket 25 move up and down along the mast 16. Moreover, the clamp bracket 25 is moved from side to side to the mast 16. Thus, the workpieces W are moved back and forth and around, so that the load added to each wheel is adjusted to the target loads N1 and N2 in order to make the run resistance of each wheel equal to enhance running stability of the clamp lift 1.

Description

  The present invention relates to a transport vehicle that transports a workpiece.

  Conventionally, in a distribution warehouse or the like, a workpiece is transferred from a transfer source to a transfer destination by a transfer vehicle. When conveying a workpiece, it is required to convey the workpiece without dropping it from the conveyance vehicle and without damaging the workpiece, and high traveling stability of the vehicle being conveyed is required. In Patent Document 1, as an improvement in stability, there is one that suppresses the turning of the vehicle body when the cargo handling vehicle (conveying vehicle) moves in the lateral direction. Specifically, for the moment of turning the vehicle body around the center of gravity due to the driving force of the drive wheel and the running resistance applied to the road wheel, the position of the center of gravity is obtained from the wheel load and the loaded load, and the drive is calculated based on the driving force of the drive wheel. The road wheel is driven by force to prevent the cargo handling vehicle from turning.

  Moreover, in patent document 2, in order to stabilize a vehicle also on the downhill road etc., the operator is alert | reported to the stability of a vehicle. Specifically, a vehicle tilt angle detection sensor is provided on the mast of the forklift, the fork is moved up and down according to the tilt of the front and rear and the left and right from the detection value by the vehicle tilt angle detection sensor, and the loaded load is moved by tilting the mast forward and backward. Is controlled to be stable. Furthermore, it is judged using a map whether the forklift is stable, and is notified to the operator.

Japanese Patent Laid-Open No. 09-110392 JP 07-242398 A

  By the way, a conveyance vehicle may convey the workpiece | work mounted on the pallet or the shelf. At this time, a conveyance vehicle may advance a leg part extended ahead to the downward direction, such as a shelf, and may handle a workpiece. For this reason, the front wheels provided on the legs of the transport vehicle often have a smaller diameter than the rear wheels. When the work is handled by the transport vehicle, the position of the center of gravity of the entire vehicle changes depending on the load of the work, and different loads act on the front wheels and the rear wheels. When the transport vehicle travels in this state, the rolling friction force generated on each front wheel and the rear wheel may be different, and the traveling stability may be slightly reduced. Furthermore, the load of the workpiece to be handled may not be applied to the wheels evenly in the left-right direction of the vehicle body. If the loads applied to the left and right wheels are different, the running resistance of the wheels to which a large load is applied increases, and the balance of the transport vehicle is lost, and a large amount of power is required for driving.

  On the other hand, in Patent Document 1, the load wheel is driven and stabilized when the cargo handling vehicle moves in the lateral direction, but is not controlled when it moves in the front-rear direction. Further, the case where the rolling frictional force of the front and rear wheels is made equal and the case where the diameters of the front and rear wheels are different are not taken into consideration. On the other hand, in Patent Document 2, the load is moved to stabilize the vehicle, but the rolling friction force in consideration of the diameters of the front wheels and the rear wheels is not examined.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a transport vehicle with higher traveling stability.

  In order to solve the above-described problems, the present invention detects a mast provided in a vertical direction, a plurality of wheels provided in a conveyance vehicle, and a load applied to the wheels in a conveyance vehicle that loads and conveys a workpiece by a loading means. Load detecting means for adjusting the load applied to the wheels, and the load adjusting means adjusts the load applied to the plurality of wheels so as to be a load corresponding to the diameter of each wheel. Features.

  According to the present invention, since the load applied to the wheel by the load adjusting means is set to a load according to the diameter of the wheel, the running resistance of each wheel can be made equal and the running stability can be improved.

  In the transport vehicle, the load adjusting means includes load moving means for moving the cargo handling means.

  Further, the transport vehicle has front wheels and rear wheels as wheels, the load moving means includes a tilt means for tilting a mast provided with the load handling means to the rear of the transport vehicle, and a lift means for moving the load handling means up and down along the mast. It is preferable to have.

  Moreover, it is preferable that the said load moving means has a side shift means to move the support member which supports a workpiece | work to the left-right direction of a conveyance vehicle.

  The transport vehicle has three or more wheels, and the transport vehicle has a counterweight that balances the weight of the workpiece, and an XY stage that moves the counterweight in the front-rear and left-right directions in the transport vehicle. The load adjusting means preferably adjusts the load detected by the load detecting means by moving the counterweight on the XY stage.

  The load detecting means is preferably a potentiometer or a load cell.

  In the transport vehicle, the transport vehicle includes a leg portion extending forward, a front wheel provided at a tip portion of the leg portion, and a rear wheel provided in the transport vehicle. On the other hand, it is preferable to have a front wheel moving means for moving the position of the front wheel and / or the leg provided at the tip of the leg.

  Further, in the transport vehicle, the leg portion includes a first leg portion that extends forward of the transport vehicle and rotates so as to move the front end portion up and down by an electric motor provided in the transport vehicle, and a distal end portion of the leg portion. A second leg connected to the front end of the first leg via a rotating shaft, the second leg has a link mechanism that receives a rotational driving force from the electric motor, and the front wheel moving means is electrically It is preferable to rotate the second leg with respect to the first leg by the rotation of the motor in a direction opposite to the rotation direction of the first leg and with a rotation amount that causes the front wheels to contact the ground on which the transport vehicle travels.

  The present invention can provide a transport vehicle with higher traveling stability.

It is a side view of the clamp lift concerning a 1st embodiment. It is a bottom view of the clamp lift concerning a 1st embodiment. (A) It is a fragmentary sectional view showing the rear wheel and load detector concerning a 1st embodiment. (B) It is a fragmentary sectional view showing the front wheel and load detector concerning a 1st embodiment. It is a front view of the clamp lift concerning a 1st embodiment. It is a front view of the clamp lift concerning a 1st embodiment. It is a flowchart of the position adjustment of the workpiece | work which concerns on 1st Embodiment. It is a graph which shows the position adjustment of the front-back direction of the workpiece | work which concerns on 1st Embodiment. It is a graph which shows the position adjustment of the horizontal direction of the workpiece | work which concerns on 1st Embodiment. It is a side view of the clamp lift concerning a 2nd embodiment. It is a flowchart of the position adjustment of the counterweight in 2nd Embodiment. It is a side view of the clamp lift concerning a 3rd embodiment. It is an enlarged side view which shows the leg part which concerns on 3rd Embodiment. It is an enlarged plan view which shows the leg part which concerns on 3rd Embodiment. It is a side view of the clamp lift concerning a 4th embodiment. It is a front view of the clamp lift concerning a 4th embodiment. It is a side view which shows the example 1 of a change of this invention. It is a top view which shows the example 1 of a change of this invention. It is an enlarged plan view which shows the stopper which concerns on the modification 1 of this invention. It is a side view which shows the example 2 of a change of this invention. It is a side view which shows the modification 3 of this invention.

(First embodiment)
Hereinafter, the conveyance vehicle concerning a 1st embodiment of the present invention is explained based on figures. Note that the vertical direction is the vertical direction in FIG. 1 and corresponds to the direction of gravity. The front-rear direction corresponds to the traveling direction of the clamp lift 1, and the front is the right direction in FIG. 1 and the rear is the left direction in FIG. The left-right direction is orthogonal to the traveling direction of the clamp lift 1 and corresponds to the horizontal direction.
A clamp lift 1 shown in FIG. 1 is a transport vehicle that transports a workpiece W placed on a shelf T. The clamp lift 1 includes a control device 4 inside the vehicle body 2. The control device 4 is a control device that controls the entire clamp lift 1. As shown in FIGS. 1 and 2, the clamp lift 1 includes a rear wheel 6 that is a pair of left and right traveling wheels at the bottom of the vehicle body 2. As shown in FIG. 3A, a rotating shaft 6 </ b> A is connected to the rear wheel 6. The rotating shaft 6A is provided with a U-shaped bracket 6B that supports the rotating shaft 6A. A connection pin 6C is provided on the upper surface of the bracket 6B so as to protrude vertically upward.

  The vehicle body 2 is provided with a load detector 7 as load detection means for detecting the weight applied to the rear wheel 6. The vehicle body 2 includes a tire house 2A that partially accommodates the rear wheel 6, and a load detector 7 is disposed in a recess 2B provided on the upper surface of the tire house 2A. As shown in FIG. 3, the load detector 7 includes upper and lower support plates 7A and 7B, a plurality of elastic damping members 7C, and a displacement detection member 7D. The upper support plate 7 </ b> A is fixed to the vehicle body 2. In the present embodiment, four coil springs are arranged on the lower surface of the support plate 7A as elastic damping members 7C at equal intervals in the front, rear, left and right directions. In the present embodiment, a potentiometer is disposed as a displacement detection member 7D at a central position surrounded by the elastic damping member 7C. The lower ends of the plurality of elastic damping members 7C and the displacement detection members 7D are set to have the same height in the vertical direction from the upper support plate 7A and are in contact with the upper surface of the lower support plate 7B. .

  A connection pin 6C is fixed at the center position of the lower surface of the support plate 7B. The support plates 7A and 7B are configured to change the interval between the support plates 7A and 7B according to the load when a load is applied to the rear wheel 6. Although the support plate 7A is fixed to the recess 2B, the support plate 7B can be displaced up and down by an elastic damping member 7C. The support plate 7B is held so as to keep a distance from the support plate 7A by the upper and lower elastic forces of the elastic damping member 7C. And the displacement detection member 7D is the structure which detects that the space | interval of support plate 7A, 7B changed, and transmits a detection result to the control apparatus 4 via the harness which is not shown in figure.

  In addition, the rear wheel 6 in this embodiment is a traveling wheel driven using an in-wheel motor. Further, a rotation drive mechanism (not shown) is provided on the connection pin 6C, and the rear wheel 6 can be steered.

  As shown in FIGS. 1 and 4, a pair of left and right connecting portions 8A is provided at the front portion of the vehicle body 2, and a pair of left and right leg portions extending forward from the front portion of the vehicle body 2 via the connecting portions 8A. 8 is provided. As shown in FIG. 3 (b), a load detector 9 as a load detection means is provided at the tip of the right leg 8 so as to be accommodated in a recess 8B provided on the lower surface of the leg 8. Yes. Below the load detector 9, a front wheel 10 is provided as a wheel. A rotation shaft 10 </ b> A is connected to the front wheel 10. The rotary shaft 10A is provided with a U-shaped bracket 10B that supports the rotary shaft 10A. A connection pin 10C is provided on the upper surface of the bracket 10B so as to protrude vertically upward. Note that the pair of left and right front wheels 10 are arranged so as to be positioned in front of the respective rear wheels 6. That is, three or more (four in this embodiment) wheels are arranged at the four corners of the front, rear, left and right in the plan view of the clamp lift 1.

  The load detector 9 includes upper and lower support plates 9A and 9B, a plurality of elastic damping members 9C, and a displacement detection member 9D. The upper support plate 9 </ b> A is fixed to the recessed portion 8 </ b> B of the leg portion 8. In the present embodiment, four coil springs are disposed on the lower surface of the support plate 9A as elastic damping members 9C at equal intervals in the front, rear, left, and right directions. In the present embodiment, a potentiometer is disposed as a displacement detection member 9D at a central position surrounded by the elastic damping member 9C. The lower ends of the plurality of elastic damping members 9C and the displacement detection members 9D are set to have the same height in the vertical direction from the upper support plate 9A and are in contact with the upper surface of the lower support plate 9B. .

  A connection pin 10C is fixed at the center position of the lower surface of the support plate 9B. The support plates 9A and 9B are configured to change the interval between the support plates 9A and 9B according to the load when a load is applied to the front wheel 10. Although the support plate 9A is fixed to the recess 8B, the support plate 9B can be displaced up and down by an elastic damping member 9C. The support plate 9B is held so as to keep a distance from the support plate 9A by the upper and lower elastic forces of the elastic damping member 9C. And the displacement detection member 9D is a structure which detects that the space | interval of support plate 9A, 9B changed, and transmits a detection result to the control apparatus 4 via the harness which is not shown in figure.

  In this embodiment, the front wheel 10 is a driven wheel, and the connection pin 10C is provided on the support plate 9B via a bearing. Therefore, the front wheel 10 has a configuration that can freely change the direction according to the travel of the clamp lift 1. In the present embodiment, the left leg 8 is not provided with the recess 8B and the load detector 9, and only the right leg 8 is provided with the recess 8B and the load detector 9.

  As shown in FIGS. 4 and 5, a pair of left and right masts 16 are supported in the vertical direction with respect to the vehicle body 2 via the rotation support shaft 15 at the connecting portion 8 </ b> A. It is erected. As shown in FIG. 4, the pair of left and right masts 16 form a frame body by a connecting member 16 </ b> A that connects the vicinity of the upper end thereof. A rotation screw shaft 17 is provided vertically toward the rotation support shaft 15 at the center in the left-right direction on the lower surface of the connecting member 16A. The rotating screw shaft 17 has an upper end connected to the coupling member 16 </ b> A via a bearing so as to be rotatable, and a lower end connected to the lifting motor 18. The elevating motor 18 is fixed to the upper surface of the rotation support shaft 15. Furthermore, the raising / lowering motor 18 is connected to the control apparatus 4, and the drive is controlled.

  The rotating screw shaft 17 is provided with an elevating part 17A that can be moved up and down along the rotating screw shaft 17. The elevating part 17 </ b> A has a ball structure that moves up and down in accordance with a thread groove provided on the rotary screw shaft 17. In this embodiment, the rotary screw shaft 17, the elevating part 17 </ b> A, the elevating motor 18, and the control device 4 constitute lift means.

  A side shift motor 20 for performing a side shift of the workpiece W is fixed to the front side of the elevating unit 17A. The side shift motor 20 can move up and down together with the lifting unit 17 </ b> A and is controlled by the control device 4. The output shaft of the side shift motor 20 is provided horizontally as the side shift rotation shaft 21 in the left-right direction of the vehicle body 2. An inscribed plate 22 is connected to each side end of the side shift rotating shaft 21. The inscribed plate 22 grips a protrusion 16B provided on inner surfaces facing the left and right of the mast 16 with a roller (not shown) that abuts from the front and rear. The side shift rotation shaft 21 is supported on the inscribed plate 22 via a bearing (not shown). Even if the side shift rotating shaft 21 is rotated by driving the side shift motor 20, the inscribed plate 22 does not rotate.

  The left and right inscribed plates 22 are provided with connecting rods 23 below the side shift rotating shaft 21. The connecting rods 23 maintain a distance so that the inscribed plates 22 on both sides come into contact with the inner surface of the mast 16. The side shift rotating shaft 21 and the connecting rod 23 are provided with a pair of side shift plates 24 on both sides of the side shift motor 20. The side shift rotating shaft 21 is provided with a thread groove, and the side shift plate 24 moves to the left and right as the side shift rotating shaft 21 rotates by a ball screw mechanism. All the thread grooves of the side shift rotating shaft 21 are formed in the same direction. Therefore, the pair of side shift plates 24 always move left and right with the same interval. The side shift plate 24 is provided with a hole through which the connecting rod 23 is inserted, and moves while maintaining the posture along the connecting rod 23 when moving to the left and right. In the present embodiment, the side shift motor 20, the side shift rotation shaft 21, the inscribed plate 22, the side shift plate 24, and the control device 4 constitute side shift means.

  The pair of side shift plates 24 is provided with a clamp bracket 25 as shown in FIG. The clamp bracket 25 has a U-shaped cross section in plan view. Side plates 25 </ b> A at the left and right ends of the clamp bracket 25 are provided so as to protrude forward of the vehicle body 2. A clamp rotating shaft 26 and a connecting rod 27 are provided horizontally and vertically on the side plates 25A at both left and right ends of the clamp bracket 25. The clamp rotation shaft 26 is rotatable on the side plate 25A via a bearing (not shown). A clamp motor 28 for rotating the clamp rotation shaft 26 is provided at the center in the left-right direction of the clamp rotation shaft 26. The clamp motor 28 is fixed to the clamp bracket 25. An output shaft of the clamp motor 28 is coaxially connected to the clamp rotation shaft 26. A thread groove is provided on the surface of the clamp rotating shaft 26, and the thread groove is oppositely directed on both sides of the clamp motor 28. The connecting rod 27 is fixed to the side plate 25A.

  The clamp rotating shaft 26 and the connecting rod 27 are provided with a pair of left and right clamp plates 29. The clamp plate 29 is disposed so that the clamp surfaces face each other. A clamp rotating shaft 26 and a connecting rod 27 are inserted through the clamp plate 29. The clamp plate 29 is provided with a ball screw structure corresponding to the screw groove of the clamp rotation shaft 26, and can be moved in the left-right direction of the vehicle body 2 by the rotation of the clamp rotation shaft 26. The clamp rotating shaft 26 is provided with thread grooves that are opposite to each other across the clamp motor 28. Therefore, when the clamp rotating shaft 26 rotates, the pair of left and right clamp plates 29 approach or separate from each other. Move to. The connecting rod 27 is slidably inserted into the clamp plate 29 and maintains the posture of the clamp plate 29. In the present embodiment, the clamp bracket 25, the clamp rotation shaft 26, the connecting rod 27, the clamp motor 28, and the clamp plate 29 constitute a support member that supports the workpiece.

  The lift means and the side shift means provided on the mast 16 can tilt forward and backward with respect to the vehicle body 2. The mast 16 is supported by the rotation support shaft 15. When the rotation support shaft 15 rotates, the mast 16 tilts back and forth about the rotation support shaft 15 as a rotation center. The connecting portion 8A is provided with a reduction gear (not shown) inside. An output shaft of a tilt motor 30 provided beside the connecting portion 8A is connected to the speed reducer. When the tilt motor 30 is driven, the mast 16 tilts through the output shaft and the speed reducer. The tilt motor 30 is connected to the control device 4, and its drive is controlled by the control device 4. In the present embodiment, the rotation support shaft 15, the tilt motor 30, and the control device 4 constitute a tilt unit. The load adjusting means is composed of lift means, side shift means, and tilt means. The load moving means is constituted by lift means, side shift means, and tilt means. The cargo handling means includes a clamp plate 29, a lift means, a side shift means, a tilt means, and the like.

Next, an effect | action is demonstrated about the adjustment for making the load added to the front wheel 10 and the rear wheel 6 in this embodiment according to each diameter.
In the present embodiment, the adjustment of the load applied to the front wheel 10 and the rear wheel 6 is performed after the work W is handled. Details will be described below with reference to FIG.
In step 1 of FIG. 6, the work W is first handled. When the workpiece W placed on the shelf T is transported by the clamp lift 1, the clamp lift 1 is first moved to a position facing the shelf T as shown in FIG. Then, the clamp lift 1 is advanced slightly toward the shelf T. Here, the control device 4 drives the elevating motor 18 to raise and lower it to a sufficient height so that the clamp plate 29 does not contact the workpiece W or the shelf T. Further, the side shift motor 20 and the clamp motor 28 are driven to widen the interval between the clamp plates 29 and move to a position facing the left and right side surfaces of the workpiece W. Then, the side surface of the workpiece W is clamped by the pair of left and right clamp plates 29. Then, the lift motor 18 is driven to lift the workpiece W, and the clamp lift 1 moves to a position away from the shelf T by facing the shelf T at a slow reverse speed.

  The end of cargo handling of the workpiece W in step 1 (S1) in FIG. 6 is when the workpiece W is clamped by the clamp plate 29 and the clamp lift 1 moves backward to a position facing the shelf T. At this time, the mast 16 is in a vertical state. Then, the process proceeds to step 2 (S2), and the load applied to each wheel of the front wheel 10 and the rear wheel 6 is detected. The load is detected by the load detectors 7 and 9, and the detected value is grasped by the control device 4. In the control device 4, the detected values of the load detectors 7 and 9 are recognized through the low-pass filter as values that vary depending on the elastic damping member 9 </ b> C. In the present embodiment, since the load detector 9 is provided only on the right front wheel 10 in the pair of left and right front wheels 10, the detected value in the front wheel 10 is only the value of the right front wheel 10.

  When detection of the load applied to the front wheel 10 and the rear wheel 6 is completed in step 2, the control device 4 calculates the target load N1 of the front wheel 10 and the target load N2 of the rear wheel 6 in step 3 (S3). Here, the target loads N1 and N2 will be described. When the clamp lift 1 grips the workpiece W, the load applied to the front wheel 10 and the rear wheel 6 changes due to the load of the workpiece W being applied. At this time, the workpiece W does not necessarily have a center of gravity at the center in the left-right direction of the vehicle body 2, and depending on the type of the workpiece W, a large deviation occurs. As a result, the load balance between the front, rear, left and right is lost, and the load applied to the front wheel 10 and the rear wheel 6 is not uniform. In particular, since the workpiece W is clamped in front of the vehicle body 2, the load of the workpiece W is applied to the front side of the vehicle body 2 in the front-rear direction. Therefore, the balance of the load applied to the front wheel 10 and the rear wheel 6 is lost.

  If the balance of the load applied to each of the four wheels (front wheel 10 and rear wheel 6) is lost, the traveling resistance of each wheel of the clamp lift 1 is different, so that traveling stability is lowered. Further, if the running resistance of each wheel is different, a large driving force is required in each driving unit. In this embodiment, power consumption may increase in each part of the motor. Therefore, it is ideal that the load applied to each of the four wheels is balanced, and the control device 4 calculates target loads N1 and N2 for adjusting the load applied to each wheel. In the present embodiment, the front-rear load balance is adjusted for the front wheel 10 and the rear wheel 6 on the right side of the vehicle body 2. The target loads N1 and N2 are also values for the right front wheel 10 and the rear wheel 6.

The target loads N1 and N2 are set in consideration of the running resistance of each wheel, and the target load of the front wheel 10 is N1 and the target load of the rear wheel 6 is N2. Here, the running resistance of the wheel will be described. The traveling resistance of the wheels traveling on the ground G is expressed by the following equation.
F = C · N / R (Formula 1)
Here, F is a rolling friction force that is a running resistance, and C is a rolling friction coefficient (constant). N is a load applied to the wheel, and R is a wheel radius.

In the clamp lift 1, in order to balance the running resistance of each wheel equally, the value of the above (Equation 1) should be equal for each wheel. Here, the load balance before and after the vehicle body 2 will be described in detail. A front wheel 10 and a rear wheel 6 are disposed as front and rear wheels of the vehicle body 2. The load applied to the front wheel 10 is a value detected by the load detector 9, and here, when it is Nf, the running resistance Ff in the front wheel 10 is expressed by the following (Equation 2).
Ff = Cf · Nf / Rf (Formula 2)
Here, Cf is a rolling friction coefficient (constant) between the front wheel 10 and the ground G, and Rf is a radius of the front wheel 10.

The load applied to the rear wheel 6 is a value detected by the load detector 7. Here, when Nr, the running resistance Fr in the rear wheel 6 is expressed by the following (Equation 3).
Fr = Cr · Nr / Rr (Formula 3)
Here, Cr is a rolling friction coefficient (constant) between the rear wheel 6 and the ground G. Rr is the radius of the rear wheel 6.

The target loads N1 and N2 are when the running resistance is equal before and after the vehicle body 2. Therefore, (Expression 2) and (Expression 3) may be the same value.
Cf · N1 / Rf = Cr · N2 / Rr (Formula 4)
Here, in the clamp lift 1, it can be assumed that the rolling friction resistance Cf between the ground G and the front wheel 10 and the rolling friction resistance Cr between the ground G and the rear wheel 6 have the same value. for that reason,
N1 / Rf = N2 / Rr (Formula 5)
It becomes.

When the value of N2 is derived from (Expression 5), N1 · Rr / Rf is obtained. Here, the sum of the loads applied to the front wheel 10 and the rear wheel 6 is expressed by the following (formula 6).
N1 + N2 = N1 · (1 + Rr / Rf)
N1 + N2 = N1. (Rf + Rr) / Rf (Formula 6)
Here, the sum of the target loads N1 and N2 does not change from the sum of the detected values detected by the load detectors 7 and 9, and is the same value. That is, the sum of Nf and Nr is the same as the sum of N1 and N2. Therefore, when the target load N1 is obtained from (Expression 6), the following (Expression 7) is obtained.
Nf + Nr = N1 + N2 = N1. (Rf + Rr) / Rf
N1 = (Nf + Nr) .Rf / (Rf + Rr) (Expression 7)

Further, when the target load N2 is obtained from (Expression 6) and (Expression 7), the following (Expression 8) is obtained.
N2 = (Nf + Nr) .Rr / (Rf + Rr) (Formula 8)
In step 3, the control device 4 calculates target loads N1 and N2 from the above (formula 7) and (formula 8). In the control device 4, the radius Rf of the front wheel 10 and the radius Rr of the rear wheel 6 are registered in advance.

  When the calculation of the target loads N1 and N2 is completed in step 3, the process proceeds to step 4 (S4). In step 4, the load Nf applied to the front wheel 10 is compared with the target load N1. Then, the load Nr applied to the rear wheel 6 is compared with the target load N2. When the respective loads are equal (Nf = N1, Nr = N2), the load in the front-rear direction is balanced in the clamp lift 1, so step 5 (S5) is skipped and the process proceeds to step 6 (S6). If the loads are not equal (Nf ≠ N1, Nr = N2), the position of the workpiece W is adjusted back and forth in step 5 to adjust the load balance.

Here, the adjustment of the load balance in the front-rear direction will be described in detail.
FIG. 7 is a graph showing a case where the workpiece W is moved after the workpiece W is clamped. The horizontal axis is the position of the mast 16 and indicates whether it is inclined forward or backward by the tilting means. The vertical axis represents the position of the clamp bracket 25 and indicates whether the position is raised or lowered from the middle position in the mast 16. A rectangular area indicated by a broken line L indicates a mechanically movable area of the mast 16 and the clamp bracket 25. In the present embodiment, the mast 16 has a forward tilt angle smaller than the rear tilt angle.

  A point A in FIG. 7 indicates the time when the workpiece W is gripped in step 1. When gripping the workpiece W, the mast 16 is not tilted back and forth but is vertical. The clamp bracket 25 is raised and lowered according to the shelf T on which the workpiece W is placed, and is slightly raised at the point A. The control device 4 tilts the mast 16 back and forth so that the loads applied from the point A to the front wheels 10 and the rear wheels 6 become the target loads N1 and N2, and further raises and lowers the clamp bracket 25. For example, when the target loads N1 and N2 are reached at the point B, the control device 4 slowly moves the mast 16 and the clamp bracket 25 to move the position of the workpiece W. Then, after the front / rear position adjustment in step 5 in FIG. 6, it is determined again in step 4 whether the weight applied to the front wheels 10 and the rear wheels 6 is equal to the target loads N1 and N2. If the loads Nr and Nf detected by the load detectors 7 and 9 are equal to the target loads N1 and N2 at the point B in FIG. Proceed to step 6.

  In the present embodiment, the control device 4 controls the mast 16 not to move forward in the position adjustment of the workpiece W. Furthermore, when the position of the workpiece W is adjusted by the control device 4, there are cases where the target loads N1 and N2 cannot be adjusted within the area of the broken line L in FIG. At that time, the control device 4 performs adjustment to move the workpiece W to the mechanical maximum movable position at the point C or the point D. When the point C or the point D is reached, the control device 4 proceeds to step 6 assuming that the position adjustment of the workpiece W has been completed.

  Next, in step 6, it is determined whether or not the loads applied to the left and right rear wheels 6 are equal. Here, it is checked whether or not the balance of the load is broken in the left-right direction of the vehicle body 2 by clamping the workpiece W. In this case as well, the above (Expression 7) and (Expression 8) can be derived in consideration of the running resistance of the pair of left and right rear wheels 6. However, in this embodiment, the rear wheel 6 uses wheels having the same radius on the left and right. Therefore, it is only necessary to determine whether the loads applied to the left and right rear wheels 6 detected by the left and right load detectors 7 are equal.

  If it is determined in step 6 that the loads applied to the left and right rear wheels 6 are equal, step 7 (S7) is omitted and the flow proceeds to the end. If the loads applied to the left and right rear wheels 6 are not equal, the left and right positions of the workpiece W are adjusted in step 7. The left / right position adjustment of the workpiece W is performed based on FIG. In FIG. 8, the vertical axis represents a load difference applied to the left and right rear wheels 6, and the horizontal axis represents the position of the clamp bracket 25 in the left-right direction. In this embodiment, a difference obtained by subtracting a load applied to the right rear wheel 6 from a load applied to the left rear wheel 6 is defined as a load difference. The left and right positions of the clamp bracket 25 are positions at which the clamp bracket 25 moves together with the side shift plate 24 by the side shift rotation shaft 21. In the initial state of the clamp lift 1, the side shift plate 24 and the clamp bracket 25 are set so that the center position in the left-right direction coincides with the center position in the left-right direction of the vehicle body 2.

  In FIG. 8, the case where the workpiece W is in the state of the position of the point E when the workpiece W is clamped will be described. In the state of point E, the load on the left rear wheel 6 is larger than the load on the right rear wheel 6. The clamp bracket 25 is the center position in the left-right direction when the workpiece W is clamped. When determining that the load on the left rear wheel 6 is large, the control device 4 drives the side shift motor 20 to rotate the side shift rotation shaft 21. Then, the pair of left and right side shift plates 24 move to the right side of the vehicle body 2. When the side shift plate 24 moves to the right side, the clamp bracket 25 and the clamp plate 29 also move to the right side, and the workpiece W moves to the right side of the clamp lift 1. Then, after the left / right position adjustment of the workpiece W in step 7 in FIG. 6, it is determined again in step 6 whether the loads applied to the left and right rear wheels 6 are equal. Here, if the load applied to the left and right rear wheels 6 is the same after moving to the position of point F in FIG. 8, the driving of the side shift motor 20 is stopped and the adjustment of the position of the workpiece W in the left-right direction is completed. This completes the flow of FIG.

  In FIG. 8, when the workpiece W is in the state of point G when the workpiece W is clamped, the control device 4 determines that the load applied to the right rear wheel 6 is large and adjusts the position of the workpiece W. . The control device 4 drives the side shift motor 20 and rotates the side shift rotating shaft 21 in the reverse direction to move the side shift plate 24 to the left side. Thereby, the clamp bracket 25 and the clamp plate 29 move to the left side. Then, when the workpiece W is moved to the left and the state of the point H is reached, that is, the load difference between the left and right sides of the rear wheel 6 is eliminated, the position adjustment of the workpiece W is finished.

  As described above, when all of the flow of FIG. 6 is completed, the control device 4 of the clamp lift 1 drives the in-wheel motor of the rear wheel 6 to transport the workpiece W to the designated transport destination.

According to this embodiment, the following effects can be obtained.
(1) The load detector 9 is provided on the front wheel 10 and the load detector 7 is provided on the rear wheel 6 to detect the load balance between the front, rear, left and right, and the work W is moved by the mast 16 and the lifting ball screw to adjust the position. By doing so, the running resistance of each wheel becomes equal, and the bias of the driving force can be eliminated, so that high running stability can be achieved.

(2) The clamp lift 1 requires a large driving force by configuring each driving unit with a motor, adjusting the position of the workpiece W to equalize the running resistance of each wheel, and eliminating the bias of the driving force. Since the resistance of the wheel can be distributed to other wheels, and furthermore, the driving force of the entire lift can be reduced, the power consumption related to travel can be improved.

(3) Since the load detector 7 is provided on the left and right rear wheels 6 and the load detector 9 is provided only on one side of the right front wheel 10, the load in the front-rear direction and the left-right direction is provided by the three load detectors 7 and 9. You can grasp the balance. Further, since only one load detector 9 is required, an increase in cost can be suppressed.

(Second Embodiment)
A second embodiment of the present invention will be described below with reference to FIGS.
In addition to the configuration of the first embodiment, a clamp lift 201 that is a transport vehicle of the present embodiment includes a counterweight 34 that balances the weight of the workpiece and the weight inside the vehicle body 2. A description will be given centering on differences from the first embodiment. In addition, about the structure which is common in 1st Embodiment, a common code | symbol is used.
A counterweight 34 is provided inside the vehicle body 2. The counterweight 34 is suspended and held by an XY stage 35 provided in a space inside the vehicle body 2.

  The XY stage 35 includes a front / rear moving unit 35A for moving the counterweight 34 in the front / rear direction of the vehicle body 2 and a left / right moving unit 35B for moving in the left / right direction. The front / rear moving unit 35A is fixed to the upper surface in the space of the vehicle body 2, and the left / right moving unit 35B is connected to the lower surface of the front / rear moving unit 35A. The counterweight 34 is connected to the left / right moving unit 35B. The counterweight 34 is held at the center position of the front, rear, left and right of the XY stage 35 as an initial state. The XY stage 35 is driven by an electric motor (not shown), and the electric motor is driven and controlled by the control device 4.

Next, the flow shown in FIG. 10 regarding the position adjustment of the counterweight 34 in the present embodiment will be described.
In the present embodiment, similarly to the first embodiment, the work W placed on the shelf T is unloaded at Step 1 (S1). The loading of the workpiece W is a state in which the clamp lift 201 is retracted and separated from the shelf T by a predetermined distance after the workpiece W is clamped and lifted by the clamp plate 29. When the loading of the workpiece W is completed, the load applied to the front wheel 10 and the rear wheel 6 is detected by the load detectors 9 and 7 in step 2 (S2). The detected load is grasped by the control device 4 through a low-pass filter. Next, target loads N1 and N2 of loads applied to the front wheel 10 and the rear wheel 6 are calculated in step 3 (S3) as in the first embodiment. In step 4 (S4), it is determined whether the loads applied to the front wheels 10 and the rear wheels 6 are equal to the target loads N1 and N2. If equal, step 5 (S5) is omitted and the process proceeds to step 6 (S6).

  In step 5, the front and rear positions of the counterweight 34 are adjusted. Specifically, the counterweight 34 is moved in the front-rear direction by the front-rear moving unit 35A of the XY stage 35. For example, when the load applied to the front wheel 10 is larger than the target load N1, the counterweight 34 is moved rearward. Conversely, when the load applied to the front wheel 10 is smaller than the target load N1, the counterweight 34 is moved to the front side. Then, the front / rear position adjustment of the counterweight 34 is finished at a position where the front wheel 10 and the rear wheel 6 become equal to the target load. Then, the process proceeds to Step 6.

  In step 6, it is determined whether the load applied to the rear wheel 6 is equal on the left and right. If the left and right are equal, step 7 (S7) is omitted and the flow ends. If the left and right loads are not equal, the counterweight 34 is adjusted to the left and right in step 7. For example, when the load applied to the left rear wheel 6 is large, the counterweight 34 is moved to the right by the left / right moving part 35 </ b> B of the XY stage 35. Conversely, when the load applied to the left rear wheel 6 is small, the counterweight 34 is moved to the left side. Then, the counterweight 34 is moved to a position where the loads applied to the left and right rear wheels 6 are equal to complete the position adjustment. When the flow of FIG. 10 ends, the clamp lift 201 transports the workpiece W to the transport destination.

According to the present embodiment, the following effects can be obtained.
(4) The load applied to each wheel can be adjusted by moving the counterweight 34 back and forth and right and left on the XY stage 35. Therefore, since it is not necessary to move the workpiece for equalizing running resistance, it is possible to prevent deterioration in safety and reduction in work efficiency.
(5) With the XY stage 35, the front / rear / left / right load balance can be adjusted, and the number of actuators can be reduced from three to two compared to the first embodiment, facilitating control. Further, cost reduction can be expected as compared with the first embodiment.

(Third embodiment)
A third embodiment of the present invention will be described below with reference to FIGS.
A clamp lift 301 which is a transport vehicle of the present embodiment has a configuration in which the leg portion 8 in the first embodiment is changed. Since the clamp lift 301 has a symmetrical configuration, the configuration on the left side of the clamp lift 301 will be described here.
As shown in FIGS. 11 and 12, a rectangular bracket leg bracket 40 is provided at the lower end of the mast 16 in the clamp lift 301. A leg bending / stretching motor 41 is provided on the lower surface of the front end of the vehicle body 2. Further, as shown in FIG. 13, a rectangular bracket pulley bracket 42 is provided next to the leg bending motor 41. A portion of the pulley bracket 42 is fixed to the lower surface of the front end of the vehicle body 2, and the remaining portion is disposed so as to protrude from the front end surface of the vehicle body 2. Further, the protruding portion of the pulley bracket 42 is arranged so that the leg bracket 40 and the plate surfaces face each other.

  The leg bracket 40 is provided with a leg rotating shaft 43 that protrudes toward the pulley bracket 42 via a bearing (not shown). A leg gear 44 is connected to the protruding end of the leg rotation shaft 43, and the leg rotation shaft 43 and the leg gear 44 are integrally rotatable. The pulley bracket 42 is provided with a pulley rotation shaft 45 that protrudes toward the leg bracket 40 via a bearing (not shown). A pulley gear 46 is connected to the protruding end of the pulley rotation shaft 45, and the pulley rotation shaft 45 and the pulley gear 46 are rotatable together. The leg rotating shaft 43 and the pulley rotating shaft 45 are arranged so as to be coaxial, and the leg gear 44 and the pulley gear 46 are also coaxial. Further, the leg gear 44 and the pulley gear 46 are arranged at intervals so as to be able to mesh with a drive gear 48 described later.

  The leg bending motor 41 is provided with an output shaft 47 that protrudes horizontally toward the front of the vehicle body 2. A driving gear 48 is provided at the front end of the output shaft 47. The leg gear 44, the pulley gear 46, and the drive gear 48 are bevel gears, and the drive gear 48 meshes with the leg gear 44 and the pulley gear 46, respectively. When the leg bending motor 41 is driven to rotate the output shaft 47, the rotational driving force of the leg bending motor 41 rotates the leg gear 44 and also the pulley gear 46. In this embodiment, the gear ratio between the drive gear 48 and the leg gear 44 is 1: 1, and the gear ratio between the drive gear 48 and the pulley gear 46 is 1: 2. That is, when the output shaft 47 rotates once, the leg gear 44 and the leg rotation shaft 43 also rotate by the same amount of rotation, and the pulley gear 46 and the pulley rotation shaft 45 have the front wheel 55 on the ground G on which the vehicle body 2 travels. It is set to rotate at a rotation amount twice that of the output shaft 47 so as to come into contact.

  Two first leg portions 51 are provided on the leg rotation shaft 43 between the leg bracket 40 and the leg gear 44. One end of the first leg 51 is fixed to the leg rotation shaft 43, and when the leg rotation shaft 43 rotates, the first leg 51 also rotates by the same amount of rotation about the leg rotation shaft 43. . The two first leg portions 51 are provided on the leg rotation shaft 43 with a slight gap, and are arranged in parallel with their plate surfaces facing each other. A connecting shaft 52 is provided at the other end of the first leg 51 so as to be parallel to the leg rotating shaft 43. The connecting shaft 52 is connected to the two first leg portions 51 via bearings (not shown). The connecting shaft 52 is provided so as to protrude through the two first leg portions 51. Two second leg portions 53 having the same shape as the first leg portion 51 are fixed to the protruding portion of the connecting shaft 52 so as to sandwich the two first leg portions 51 from both sides. The second leg portion 53 is configured to rotate by the same amount of rotation as the connecting shaft 52 with the connecting shaft 52 as an axis.

  A front wheel shaft 54 that connects the two second leg portions 53 is provided at the end of the second leg portion 53 opposite to the side on which the connection shaft 52 is provided. The front wheel shaft 54 is fixed to the two second leg portions 53 at the same interval as the interval at which the two second leg portions 53 are fixed to the connecting shaft 52. For this reason, the two second leg portions 53 are held in parallel with their plate surfaces facing each other. A front wheel 55 is rotatably provided on the front wheel shaft 54 between two second leg portions 53 via a bearing (not shown). In the present embodiment, the leg rotating shaft 43 and the pulley rotating shaft 45 are coaxial and are provided in a horizontal state having the same height, and the front wheel shaft 54 has a leg rotating shaft as shown in FIG. 43 and the pulley rotation shaft 45 are provided at the same height. That is, the radius of the front wheel 55 is set according to the height of the front wheel shaft 54.

  The pulley rotation shaft 45 is provided with a first pulley 57 between the pulley bracket 42 and the pulley gear 46. The first pulley 57 is fixed to the pulley rotation shaft 45 and rotates together with the pulley rotation shaft 45. On the other hand, a second pulley 58 is provided at the protruding end of the connecting shaft 52 on the pulley bracket 42 side, as shown in FIG. The second pulley 58 is fixed to the connecting shaft 52 and rotates together with the connecting shaft 52. The 1st pulley 57 and the 2nd pulley 58 are arrange | positioned so that it may become the same position of the left-right direction. That is, in the plan view shown in FIG. 13, the second pulley 58 is disposed in front of the first pulley 57. A pulley belt 59 that connects the first pulley 57 and the second pulley 58 is provided. The rotation of the first pulley 57 can be transmitted to the second pulley 58 by the pulley belt 59. In the present embodiment, the first pulley 57 and the second pulley 58 have the same diameter, and the rotation amount of the first pulley 57 and the rotation amount of the second pulley 58 are set to be always the same. In the present embodiment, the rotational force of the leg bending motor 41 is supplied to the second leg 53 by the pulley rotating shaft 45, the pulley gear 46, the connecting shaft 52, the first pulley 57, the second pulley 58, and the pulley belt 59. A link mechanism for transmitting to is configured.

  As shown in FIGS. 12 and 13, a leg restricting member 60 that connects the left and right leg brackets 40 is provided at the lower end of the front end of the leg bracket 40. The leg restricting member 60 is a rod-like member having a right-angled triangular section, and is provided such that a right-angle portion in the cross-section is located at the lower front end of the leg bracket 40. The leg restricting member 60 is provided as a stopper, and restricts the first leg 51 from rotating below the horizontal when the leg rotating shaft 43 rotates around the leg rotating shaft 43. The leg restricting member 60 connects the pair of left and right leg brackets 40 to increase the rigidity. In the present embodiment, the first leg 51, the second leg 53 and the like constitute a front wheel moving means.

Next, load adjustment in the present embodiment will be described.
As shown in FIG. 11, the clamp lift 301 is in a state where the workpiece W is not clamped and the first leg portion 51 is inclined slightly upward. The second leg portion 53 is inclined from the connecting shaft 52 toward the front and obliquely downward. The control device 4 of the clamp lift 301 maintains the first leg 51 and the second leg 53 in the state shown in FIG. 11 by driving the leg bending motor 41. And the workpiece | work W mounted on the shelf T is clamped similarly to 1st Embodiment and 2nd Embodiment. Then, after lifting the workpiece W, the workpiece W moves backward to a position away from the shelf T by a predetermined distance.

  The clamp lift 301 detects the load applied to the front wheel 55 and the rear wheel 6 after handling the workpiece W. The load applied to the rear wheel 6 is detected by the load detector 7 and the detected value is grasped by the control device 4 via the low-pass filter. The load applied to the front wheel 55 is grasped from the output of the leg bending / stretching motor 41. Specifically, in order to maintain the posture positions of the first leg portion 51 and the second leg portion 53 by the control device 4, the output of the leg bending / stretching motor 41 is always controlled. And the map of the output of the leg bending motor 41 and the load applied to the front wheel 55 is registered in advance, and the load is grasped. When the weight of the front wheel 55 increases, the leg bending motor 41 also increases the vertical drag and requires a large motor torque. That is, it is possible to detect a load applied to the front wheel 55 as a vertical drag from the motor torque.

  Next, when the loads applied to the front wheel 55 and the rear wheel 6 are detected, the target loads N1 and N2 are calculated from (Expression 7) and (Expression 8) as in the first embodiment. And the difference with target load N1, N2 is calculated, and the load balance in the front-back direction is adjusted. Specifically, a command is issued from the control device 4 to the leg bending motor 41 to move the front wheel 55 back and forth with respect to the vehicle body 2. First, it is determined whether the front wheel 55 is moved forward or backward from the difference between the target loads N1 and N2. For example, when moving forward, the leg bending motor 41 is driven from the control device 4 to rotate the output shaft 47. Then, the drive gear 48 provided on the output shaft 47 rotates to rotate the leg gear 44 and the pulley gear 46. When the leg gear 44 rotates, the leg rotating shaft 43 and the two first leg parts 51 also rotate together. At this time, the first leg 51 rotates the connecting shaft 52 in a direction approaching the ground G.

  On the other hand, when the pulley gear 46 rotates, the pulley rotation shaft 45 and the first pulley 57 rotate. At this time, the pulley rotation shaft 45 and the first pulley 57 rotate in the direction opposite to the rotation direction of the leg rotation shaft 43 and the first leg 51. The rotation amount of the pulley rotation shaft 45 and the first pulley 57 is twice the rotation amount of the leg rotation shaft 43 and the first leg 51. When the first pulley 57 rotates, the pulley belt 59 rotates as much as the first pulley 57, and the amount of rotation is transmitted to the second pulley 58. The second pulley 58 is fixed to the connecting shaft 52 and is also configured to interlock with the second leg 53 fixed to the connecting shaft 52. Therefore, the rotation of the first pulley 57 is transmitted to the second leg portion 53 via the pulley belt 59 and the second pulley 58.

  When the first leg 51 rotates with the leg rotation shaft 43 as an axis to bring the connecting shaft 52 closer to the ground G, the height of the connecting shaft 52 from the ground G decreases. On the other hand, the second leg portion 53 receives rotation from the first pulley 57 and rotates in the opposite direction to the first leg portion 51 by a double rotation amount. That is, the front wheel shaft 54 is always maintained at the same height, and the front wheel 55 is maintained at a position in contact with the ground G. Then, as the first leg portion 51 and the second leg portion 53 approach horizontally, the position of the front wheel 55 moves away toward the front of the vehicle body 2. The control device 4 monitors the output of the leg bending / extending motor 41 as a reaction force of the load applied to the front wheel 55, and determines the load applied to the front wheel 55 from a previously registered map. Then, when the load applied to the front wheel 55 becomes equal to the target load N1, the leg bending motor 41 is stopped. At this time, the control device 4 also detects the load applied to the rear wheel 6 by the load detector 7 and determines whether it is equal to the target load N2. Then, when the load balance in the front-rear direction is achieved, the position adjustment of the front wheel 55 is finished.

  When the control device 4 finishes the position adjustment of the front wheel 55 in the front-rear direction, the control device 4 adjusts the left and right load balance by the load detector 7 provided on the pair of left and right rear wheels 6. The left and right load balance is adjusted by moving the side shift plate 24 to the left and right by the side shift motor 20 and the side shift rotating shaft 21 as in the first embodiment. Then, when the adjustment of the load balance in the front-rear direction and the left-right direction is finished, the control device 4 drives the in-wheel motor of the rear wheel 6 to transport the workpiece W to the transport destination.

According to this embodiment, in addition to the effects of the first embodiment, the following effects can be obtained.
(8) Since the front wheel 55 can be moved back and forth with respect to the vehicle body 2, the front wheel 55 can be moved back and forth to adjust the load balance in the front and back direction, thereby improving running stability.
(9) The load applied to the front wheel 55 can be grasped by detecting the motor torque of the leg bending motor 41, and there is no need to use a potentiometer or the like.

(10) Since the front wheel 55 is moved back and forth by driving the leg bending motor 41, the leg bending motor 41 can be finely controlled and the position of the front wheel 55 can be adjusted with high accuracy.
(11) Since the front wheel 55 is configured to rotate the second leg portion 53 by the first pulley 57, the second pulley 58, and the pulley belt 59 so as to always contact the ground G, the clamp lift 301 is securely attached. Can be supported.

(Fourth embodiment)
A fourth embodiment of the present invention will be described below with reference to FIGS.
In this embodiment, the structure which concerns on the leg part 8 of 1st Embodiment is changed. The changes will be described below.
The clamp lift 401 is provided with a leg support portion 65 projecting forward from a connecting portion 8A provided at the lower portion of the pair of left and right masts 16. A leg rotation pin 66 is passed through the front end of the leg support 65 in the vertical direction via a bearing (not shown). At the upper end of the leg rotation pin 66, a rotary motor 67 is disposed with its output shaft integrated with the leg rotation pin 66. The main body of the rotary motor 67 is fixed to the connecting portion 8A.

  A leg portion 68 having a bifurcated portion so as to sandwich the upper and lower sides of the leg portion support portion 65 is connected to the leg portion rotation pin 66. A load detector 9 and a front wheel 10 are provided at the tip of the leg portion 68. When the rotary motor 67 is driven, both the leg rotation pin 66 and the leg 68 rotate in the horizontal direction. In addition, the leg part support part 65, the leg part rotation pin 66, the rotation motor 67, the leg part 68, the load detector 9, and the front wheel 10 are provided symmetrically. The rotary motor 67 is controlled by the control device 4. The pair of legs 68 can be moved close to and away from each other by opening and closing the left and right leg rotation pins 66 by driving the rotary motor 67. The control device 4 can independently control the left and right rotary motors 67. However, priority control is performed so as to make the legs 68 symmetrical with synchronization as much as possible.

The adjustment of the load balance in this embodiment will be described.
In the present embodiment, similarly to the first embodiment, the workpiece W is clamped by the clamp plate 29 and the workpiece W is loaded. Thereafter, the load applied to each of the front wheel 10 and the rear wheel 6 is detected by the load detectors 9 and 7. And the control apparatus 4 determines a load balance from the load added to four wheels, a pair of left and right front wheels 10 and rear wheels 6. The control device 4 rotates the left and right leg portions 68 in the horizontal direction, and calculates to which position the front wheel 10 is moved to equalize the load applied to the four wheels. When the target position is determined, the left and right rotating motors 67 are driven by a predetermined amount to rotate the left and right leg portions 68 in the horizontal direction. And if the front wheel 10 reaches | attains a target position, the load added to four wheels will be confirmed and adjustment of load balance will be complete | finished. And the control apparatus 4 drives the in-wheel motor of the rear wheel 6, and conveys the workpiece | work W to the designated conveyance destination.

In this embodiment, the following effects are produced.
(12) Since the leg portion 68 is provided so as to be rotatable in the horizontal direction by driving the rotary motor 67 around the leg rotation pin 66, the front wheel 10 can be moved obliquely with respect to the vehicle body 2, and the load balance can be reduced. Adjustment is easy.
(13) The pair of left and right leg portions 68 are rotated by the left and right independent rotary motors 67, and the pair of left and right front wheels 10 can move so that their positions can be adjusted. Therefore, the load balance can be adjusted without moving the side shift plate 24 that clamps the workpiece W.

The present invention is not limited to the above embodiment, and modifications of the present invention will be described below.
In the third embodiment, the front wheel 55 is configured to move back and forth due to the bending and stretching of the first leg portion 51 and the second leg portion 53, but the front wheel 55 may be moved back and forth with a configuration that does not bend and stretch.
For example, the modification 1 may be configured using a cylinder 70 as shown in FIGS. 16 and 17. In the clamp lift 501 of FIGS. 16 and 17, a cylinder rod 70 </ b> A is provided at a position slightly above the front surface of the mast 16 so that the cylinder rod 70 </ b> A can extend and contract downward. Here, a hydraulic device 71 is provided in the vehicle body 2 as a drive source of the cylinder 70. The lower end of the cylinder rod 70A is provided with a lower end portion 70B having a hole penetrating left and right as shown in FIG. 18, and a connecting pin 72 extending left and right is rotatably inserted into the lower end portion 70B via a bearing 70C. Yes. Below the cylinder 70, a rod bracket 73 is provided on the front surface of the mast 16 at a position sandwiching the cylinder rod 70A from the left and right.

  The rod bracket 73 is provided with a vertically long hole 73A through which the connecting pin 72 is inserted. At both ends of the connecting pin 72, an enlarged diameter portion 75 having a diameter larger than that of the connecting pin 72 is provided, and the connecting pin 72 is configured not to be detached from the long hole 73A. The connecting pin 72 is connected to a rectangular plate-like leg portion 76 that is opposed to the left and right rod brackets 73 in parallel. One end of the leg portion 76 is connected to the connecting pin 72, and the other end is connected to the front wheel shaft 79. The front wheel shaft 79 connects the leg portions 76 which are two opposing plates in the same manner as the connecting pin 72. The front wheel shaft 79 is provided with a front wheel 80 between the plates of the leg portions 76. The front wheel 80 is supported on the front wheel shaft 79 via a bearing (not shown).

  A cylinder bracket 81 protruding forward is fixed to the lower end portion 70B of the cylinder rod 70A as shown in FIG. The cylinder bracket 81 is provided with a hole penetrating left and right, and a stopper cylinder 82 is inserted through the hole. The stopper cylinder 82 has two oil chambers on both sides in the left-right direction, and is provided with stopper rods 82 </ b> A that can expand and contract from the two oil chambers to the left and right. A rectangular stopper 84 is provided at the tip of the stopper rod 82A. The stopper 84 is disposed close to the leg portion 76, and when the hydraulic fluid is supplied to the stopper cylinder 82 from the hydraulic device 71, the stopper 84 abuts on the leg portion 76 and supports the leg portion 76 to fix the position. It is.

  In this modified example, it is possible to estimate the vertical drag that is the gravity applied to the front wheel 80 from the hydraulic pressure of the cylinder 70, and it is possible to determine the load balance as in the third embodiment. Then, the control device 4 drives the hydraulic device 71 in accordance with the load balance, moves the stopper rod 82A slightly in the stopper cylinder 82 in the stopper cylinder 82, and separates the stopper 84 from the leg portion 76. . Then, the hydraulic oil is supplied to or discharged from the cylinder 70, and the cylinder rod 70 </ b> A is expanded and contracted to move the lower end portion 70 </ b> B of the cylinder rod 70 </ b> A along the elongated hole 73 </ b> A of the rod bracket 73. As the lower end portion 70B moves up and down along the long hole 73A, the leg portion 76 changes its inclination with respect to the ground G, and the front wheel 80 moves back and forth. The control device 4 moves the front wheel 80 to a position where the target load balance is achieved, then supplies hydraulic oil to the stopper cylinder 82 from the hydraulic device 71, and abuts the stopper 84 against the leg portion 76 to fix the position. . Thus, the front wheel 80 may be moved back and forth by the cylinder 70.

  Further, as a second modification, for example, the front wheel 10 of the clamp lift 601 may be moved back and forth as shown in FIG. In FIG. 19, a space 2 </ b> C is provided below the vehicle body 2. And the leg part 91 which can be moved forwards or backwards from the space 2C is provided in the lower part of the mast 16. A rack 91A is formed on the upper surface of the leg portion 91. A drive motor 92 is provided above the leg portion 91 on the front surface of the mast 16. The drive motor 92 is provided with a pinion 93 on the output shaft, and the pinion 93 is disposed at a position where the rack 91A is engaged. In the clamp lift 601 in FIG. 19, the control device 4 drives the drive motor 92 to move the leg 91 forward and backward from the space 2 </ b> C to move the position of the front wheel 10. In this way, the front wheel 10 may be moved back and forth by the rack and pinion structure.

As a third modification, the clamp lift 701 may move the clamp plate 29 back and forth with a cylinder 95 as shown in FIG. 20 as a structure for moving the clamp plate 29 for clamping the workpiece W back and forth. A pair of cylinders 95 may be provided on the clamp bracket 25 so as to protrude forward, and the clamp plate 29 may be fixed to the tip of the cylinder rod 95A of the cylinder 95. The cylinder 95 is not limited to a hydraulic cylinder but may be an electric cylinder.
In the clamp lift 601 shown in FIG. 19, the clamp plate 29 may be moved back and forth by the cylinder 90, and the leg 8 may be bent as in the third embodiment to move the front wheel 10 back and forth. Further, as in the fourth embodiment, the leg portion 8 may be displaced so as to be rotatable left and right. The load balance can be easily changed by making the positions of the workpiece W and wheels freely changeable by a plurality of movable parts.

In the embodiments, the position of the workpiece W or the counterweight 34 may be adjusted while the clamp lift is running. For the position adjustment during traveling, it is preferable that the adjustment speed of each driving motor is set to be slow and adjusted slowly.
The load detectors 7 and 9 may continue to detect the load applied to each wheel at all times. Then, the position of the workpiece W or the counterweight 34 may always be adjusted based on the detection value detected at all times.
The target loads N1 and N2 may be calculated in consideration of the rolling friction resistance C between the wheels and the ground G for each wheel. The target loads N1 and N2 can be accurately calculated even when the state of the ground G changes only for some of the wheels depending on the travel position of the clamp lift of each embodiment. The rolling friction resistance C is preferably registered in the control device 4 in advance.

The load detectors 7 and 9 are not limited to potentiometers, and load cells may be used.
In the clamp lift of each embodiment, the wheels do not have to be a pair of left and right. Wheels with different diameters may be used on the left and right. In that case, if the position is adjusted by calculating the target load in the left-right direction using (Equation 7) and (Equation 8) described in the first embodiment. good. If it does so, running resistance can be made equal, considering the diameter of a wheel on either side, and running stability can be improved.

In the first embodiment, load detectors 9 may be provided on both sides of the pair of left and right front wheels 10. By detecting the load applied to each of the two front wheels 10 and the two rear wheels 6, the load balance can be grasped more accurately.
In each embodiment, the position adjustment for correcting the load balance is not limited to the case where the position adjustment in the left-right direction is performed after the position adjustment in the front-rear direction. After the position adjustment in the left-right direction, the position adjustment in the front-rear direction may be performed.

In the third embodiment, the gear ratio between the leg gear 44 and the pulley gear 46 is not limited to 1: 2. The amount of rotation of the first leg 51 and the second leg 53 may be one to two, and the ratio of the amounts of rotation may be set by making the diameters of the first pulley 57 and the second pulley 58 different.
In the third embodiment, the ratio of the rotation amounts of the first leg 51 and the second leg 53 is not limited to 1: 2. What is necessary is just to rotate until the front wheel 55 contacts the ground G.
In the third embodiment, the first pulley 57, the second pulley 58, and the pulley belt 59 are not limited to the pulley structure. A chain sprocket mechanism may be adopted. Moreover, it is good also as a structure which transmits rotation using a gear and a shaft.
○ The tilt means, lift means, and side shift means are not limited to the ball screw mechanism. A hydraulic or electric cylinder may be used.

In the adjustment of the load balance in the first embodiment, the control device 4 may end the adjustment when the load applied to each wheel becomes a value close to the target load. At this time, plus or minus 5% of the target load may be set as an allowable value.
As a load position adjusting means, a forklift may be used to reach the front wheels to adjust the position in the front-rear direction.
The present invention can be applied to other than the clamp lift. You may apply to the vehicle of attachments, such as a fork and a bucket.

DESCRIPTION OF SYMBOLS 1 Clamp lift 2 Car body 2A Tire house 4 Control apparatus 6 Rear wheel 6A Rotating shaft 6B Bracket 6C Connection pin 7, 9 Load detector 7A, 7B, 9A, 9B Support plate 7C, 9C Elastic damping member 7D, 9D Displacement detection member 8 Leg portion 8A Connecting portion 8B Recessed portion 10 Front wheel 10A Rotating shaft 10B Bracket 10C Connection pin 15 Rotating support shaft 16 Mast 16A Connecting member 16B Projection 17 Rotating screw shaft 17A Lifting portion 18 Lifting motor 20 Side shift motor 21 Side shift rotating shaft 22 Inscribed plate 23 Connecting rod 24 Side shift plate 25 Clamp bracket 25A Side plate 26 Clamp rotating shaft 27 Connecting rod 28 Clamp motor 29 Clamp plate 30 Tilt motor 34 Counterweight 35 XY stage 35A Back and forth moving section 35B Left and right moving section 40 Leg bracket 41 Leg flexion Motor 42 Pulley bracket 43 Leg rotation shaft 44 Leg gear 45 Pulley rotation shaft 46 Pulley gear 47 Output shaft 48 Drive gear 51 First leg 52 Connection shaft 53 Second leg 54 Front wheel shaft 55 Front wheel 57 First pulley 58 First Two pulleys 59 Pulley belt 60 Leg regulating member G Ground N1 Target load (front wheel 10)
N2 target load (rear wheel 6)
T shelf W work

Claims (8)

In a transport vehicle that unloads and transports workpieces with the handling means,
A mast provided in a vertical direction;
A plurality of wheels provided on the transport vehicle;
Load detecting means for detecting a load applied to the wheel;
Load adjusting means for adjusting the load applied to the wheel,
The said load adjustment means adjusts the load added to these wheels so that it may become a load according to the diameter of each said wheel. The load adjusting means is
The conveyance vehicle according to claim 1, further comprising load moving means for moving the cargo handling means. The transport vehicle has front wheels and rear wheels as the wheels,
3. The load moving means comprises tilt means for tilting a mast provided with the cargo handling means to the rear of the transport vehicle, and lift means for raising and lowering the cargo handling means along the mast. The transport vehicle described.   The transport vehicle according to claim 2, wherein the load moving means includes side shift means for moving a support member that supports a workpiece in a left-right direction of the transport vehicle. The transport vehicle has three or more wheels.
The transport vehicle has a counterweight that balances the weight of the workpiece, and an XY stage that moves the counterweight in the front-rear and left-right directions in the transport vehicle,
The transport vehicle according to claim 1, wherein the load adjusting unit adjusts the load detected by the load detecting unit by moving the counterweight on the XY stage.   The transport vehicle according to any one of claims 1 to 5, wherein the load detection means is a potentiometer or a load cell. The transport vehicle includes a leg portion extending forward, the front wheel provided at a tip portion of the leg portion, and the rear wheel provided in the transport vehicle.
2. The transport according to claim 1, wherein the load adjusting unit includes a front wheel moving unit configured to move a position of the front wheel and / or the leg portion provided at a tip portion of the leg portion with respect to the transport vehicle. vehicle. The leg portion includes a first leg portion that extends forward of the conveyance vehicle and rotates so as to raise and lower a front end portion by an electric motor provided in the conveyance vehicle, and a tip portion of the leg portion. A second leg connected to the front end of the leg via a rotating shaft,
The second leg has a link mechanism that receives a rotational driving force from the electric motor,
The front wheel moving means is configured to rotate the electric motor so that the second leg portion is opposite to the first leg portion in a direction opposite to the rotation direction of the first leg portion, and the front wheel is on the ground on which the transport vehicle travels. The conveyance vehicle according to claim 7, wherein the conveyance vehicle is rotated by a rotation amount to be contacted.

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