JP4953715B2 - Lifting height detection device for lifting device - Google Patents

Description

  The present invention relates to detection of lifting height of a lifting tool in a lifting device using a hydraulic system.

  Conventionally, forklifts have been used to detect the lift of the fork, and workability and safety are improved by using the detected lift. For example, in the technique of Patent Document 1, an encoder is attached to a motor that drives a pump, and the lift is detected from the rotational speed of the motor. In the technique of Patent Document 2, an encoder is connected to a reel connected to a fork by a wire. Is attached, and the lift is detected from the number of rotations of the reel. In a multi-stage mast device, for example, as shown in Patent Document 3, the height of the lift bracket relative to the inner mast is combined with a detector that detects the height of the inner mast relative to the outer mast to increase the lift height. May be detected.

JP 2003-252589 A JP 2004-75347 A JP 2005-82396 A

Now, as in the technique of Patent Document 1, if the lift is calculated from the number of rotations of the motor, it becomes possible to detect the lift with a simple configuration, and the pump is considered by considering the volumetric efficiency of the pump. Detection error due to internal leakage is suppressed. However, since the volumetric efficiency of the pump does not always become a constant value, it is desirable to reflect the volumetric efficiency of the pump at that time in the detection of lift.
Further, according to the technique of Patent Document 3, since it is not necessary to bridge the signal line from the detector from the movable mast to the fixed mast, it is possible to detect the elevation while suppressing the deterioration of the visual field. However, since the detector for detecting the height of the lift bracket with respect to the movable mast and the transmission chain for the detection are provided on the movable mast, the influence on the field of view is still left.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to enable accurate elevation detection without deteriorating the field of view.

  In order to achieve the above object, the present invention includes first and second cylinders for raising and lowering a lifting tool, supplying hydraulic oil to the first and second cylinders by a pump and extending the cylinders to A lifting device that raises the lifting tool, collects hydraulic oil from the first and second cylinders through the pump, shortens each cylinder, and lowers the lifting tool, and operates with priority on the first cylinder. In a lifting device to which hydraulic oil is supplied and hydraulic oil is preferentially collected from the second cylinder, a lifting height detecting device for detecting a lifting height of the lifting tool, the pump or the pump Rotation detection means attached to the connected motor and outputting a signal corresponding to the number of rotations thereof; and lift detection means connected to the lifting tool and outputting a signal corresponding to the lifting amount of the lifting tool; , Rotation detection First lifting height deriving means for calculating the lifting height of the lifting tool based on the output of the means; and second lifting height deriving means for calculating the lifting height of the lifting tool based on the output of the lifting detection means Selecting means for selecting one of the first and second lifting height deriving means, and the selecting means selects the first lifting height deriving means when the first cylinder expands and contracts. When the second cylinder expands and contracts, the second lifting height deriving means is selected.

  According to the present invention as described above, when the lifting tool moves up and down in the first cylinder, the lifting height of the lifting tool is calculated based on the output of the rotation detecting means, and when the lifting tool moves up and down in the second cylinder. The height of the lifting tool is calculated based on the output of the lifting detection means. Therefore, in the lifting apparatus according to the present invention, the first cylinder is extended after the second cylinder is extended, and the first cylinder is shortened after the second cylinder is shortened. As a result, the lifting height can be accurately detected in the entire range in which the lifting / lowering tool moves up and down from the state in which the first cylinder is shortened to the state in which the second cylinder is fully extended. In addition, since it is not necessary to provide another lifting detection means connected to the lifting tool so as to correspond to the lifting and lowering of the lifting tool in the first cylinder, it is possible to suppress the deterioration of the visibility.

  Whether the first cylinder in the selection means is expanding or contracting is determined by, for example, the presence or absence of the output of the lift detection means during the operation (rotation) of the pump, or the presence or absence of an output change. Can be done from. That is, when the pump is operating, it is determined that the first cylinder is expanding and contracting if there is no change in the output or output of the lift detection means, and conversely if there is a change in output or output, the second It can be determined that the cylinder is expanding and contracting. Further, for example, the current lift is within the lift range of the lifting tool due to the expansion and contraction of the first cylinder, that is, from the lift in the state where the first cylinder is shortened to the lift in the state where the first cylinder is fully extended. If it is, it can be determined that the first cylinder is expanding and contracting, otherwise it can be determined that the second cylinder is expanding and contracting. In addition to these, it is possible to provide another detection means for the lifting tool and the cylinder within a range that does not obstruct the field of view, and to determine from the output.

  In the above configuration, the lifting tool includes a movable mast that is supported by the fixed mast so as to be movable up and down, and a movable base that is supported by the movable mast so as to be movable up and down, and the first cylinder is configured by the movable mast. The mast is provided so that the movable base moves up and down with respect to the movable mast by extension and contraction, and the second cylinder is arranged so that the movable mast moves up and down with respect to the fixed mast by extension and contraction. Where provided, the lifting detection means is connected to the movable mast and outputs a signal corresponding to the lifting amount of the movable mast, and the first lifting height deriving means is the rotation The lift of the movable base is calculated based on the output of the detection means, and the second lift height deriving means determines the output of the lift detection means and the movable mast in the state where the first cylinder is fully extended. It can be made to calculate the lift height of the movable table based on the height of the movable table to be.

  In this way, when the movable table moves up and down in the first cylinder, the lift of the movable table is calculated based on the output of the rotation detecting means, and when the movable mast moves up and down in the second cylinder, The lift of the movable base is calculated based on the output of the detection means and the height (known value) of the movable base with respect to the movable mast in the state where the first cylinder is fully extended. Therefore, it is possible to accurately detect the lifting height in the entire range in which the movable table moves up and down with respect to the fixed mast regardless of which cylinder is used for raising and lowering, and also for moving the movable table in the first cylinder. Since it is not necessary to provide a separate lift detection means in connection with the movable base so as to correspond, it is possible to suppress the deterioration of the field of view.

  As the second lifting height deriving means, the lifting height of the movable mast is calculated based on the output of the lifting detection means, and this is added to the height of the movable stand relative to the movable mast to calculate the lifting height of the movable stand. The amount of change in the height of the movable mast is calculated based on the output of the moving detection unit and the output of the lift detection means, and the sum of this is added to the height of the movable table relative to the movable mast to calculate the height of the movable table. You can adopt things. Further, when the output of the lift detection means is a pulse signal, the pulse signal is counted and the lift of the movable mast and the amount of change in lift can be calculated from the counted number. The height of the movable table relative to the movable mast can be added by converting the height of the movable table to the count number and starting counting the pulse signal from the count number.

  In the above configuration, the first lifting height deriving means includes the output of the rotation detecting means when the second cylinder extends and contracts, and the lifting height calculated by the second lifting height deriving means. And calculating a coefficient representing the relationship between the output of the rotation detecting means and the lift, and based on the coefficient and the output of the rotation detecting means when the first cylinder expands and contracts. The high can be calculated.

In this way, since the coefficient is obtained in a state where the hydraulic oil is actually flowing through the pump and used for calculating the lift, the accuracy of the calculated lift can be improved. That is, the relationship between the output of the rotation detecting means and the lift calculated by the first lift deriving means is determined by factors such as the performance of the rotation detecting means and the pump, the dimensions of the first cylinder, etc. The volumetric efficiency changes depending on the use conditions such as the load state, and other factors may change due to aging, etc., so a constant relationship is not always maintained. Therefore, by obtaining a coefficient representing such a relationship, the actual relationship can be reflected in the calculation of the lift.
Note that the coefficient is calculated not only during expansion and contraction of the second cylinder, but also only when the second cylinder starts to expand or contract, or intermittently at predetermined time intervals. Can do. In addition, when the coefficient is calculated a plurality of times, in addition to using the last calculated coefficient, an average value or a peak value of the calculated result can be used for calculating the lift.

  As described above, according to the present invention, it is possible to accurately detect the lifting height in the entire range in which the lifting tool is raised and lowered in the lifting device. In addition, although it is connected to the lifting tool so as to correspond to the lifting and lowering of the lifting tool in the second cylinder, the lifting detection means is provided, but it is connected to the lifting tool so as to correspond to the lifting and lowering of the lifting tool in the first cylinder. Since there is no need to further provide a lift detection means, the field of view can be prevented from deteriorating. Furthermore, in the present invention, the calculated lift is calculated by using the coefficient obtained from the lift calculated by the second lift deriving means for calculating the lift in the first lift deriving means. Accuracy can be improved.

  Hereinafter, an embodiment in which the present invention is applied to a forklift will be described with reference to the drawings.

  As shown in FIG. 1, the forklift according to this embodiment includes a pair of left and right straddle legs 2 extending rearward at the rear part of a vehicle body 1, and a rear wheel 3 is provided at the front end part of each straddle leg 2. As shown in FIGS. 1 and 2, a front wheel 4 is provided at the front center of the vehicle body 1, various hydraulic devices are mounted on the right side, and a control device 5 is mounted on the left side. An inverter 6 is mounted integrally with the control device 5, and the motor 22 described later is controlled by controlling the inverter 6 by the control device 5. As shown in FIG. 2, a battery 7 serving as a drive source for the forklift is mounted on the rear portion of the vehicle body 1.

As shown in FIGS. 1 and 2, a mast device 8 is erected on the rear portion of the vehicle body 1. The mast device 8 includes an outer mast 9 fixedly supported by the vehicle body 1, a middle mast 10 supported by the outer mast 9 so as to be movable up and down, and an inner mast 11 supported by the middle mast 10 so as to be movable up and down. And a second cylinder 13 provided over the outer mast 9 and the middle mast 10.
A driver's cab 14 on which an operator is boarded is supported by the inner mast 11 so as to be able to move up and down. As shown in FIG. 3, a first cylinder 12 supports a chain connecting the inner mast 11 and the driver's cab 14. Thus, when the first cylinder 12 extends, the cab 14 rises with respect to the inner mast 11, and when the first cylinder 12 shortens, the cab 14 descends. The chain connecting the outer mast 9 and the inner mast 11 is supported by the middle mast 10, and when the second cylinder 13 is extended, the middle mast 10 and the inner mast 11 are raised with respect to the outer mast 9, and when shortened, the middle mast 10 and the inner mast 11 are increased. Descends. As shown in FIGS. 1 and 2, the cab 14 is disposed behind the mast device 8, and each mast, cylinder, and chain are positioned in front of the operator on the cab 14. .

  As shown in FIG. 1, the floor of the cab 14 is provided with a pair of left and right forks 15 extending rearward, and the front wall is configured to rotate the front wheel 4 as a steering wheel and change its direction. A steering handle 16 and an operation box 17 for raising and lowering the cab 14 are provided. The operation box 17 is provided with an ascending switch 17A for instructing to raise the cab 14 and a descending switch 17B for instructing to descend, and when the operator performs a switch operation, the ascending instruction or the descending instruction Is transmitted to the control device 5 as a signal. Further, an accelerator 18 for adjusting the traveling speed by rotating the front wheels 4 as drive wheels is provided on the front wall portion of the cab 14.

  As shown in FIG. 3, the outer mast 9 is provided with a wire type rotation sensor 19, and the wire is connected to the middle mast 10. The rotation sensor 19 is composed of an encoder and outputs a pulse signal according to the amount of elevation of the middle mast 10 with respect to the outer mast 9, which is transmitted to the control device 5.

  The hydraulic device provided in the vehicle body 1 mainly includes a tank 20 for storing hydraulic oil, a pump 21, a motor 22 connected to the pump 21 and rotating integrally, a rotation sensor 23 for detecting the number of rotations of the motor 22, And a valve 24 for controlling the flow of hydraulic oil, and hydraulic piping connecting the devices. As shown in FIG. 3, the tank 20 and the pump 21, the pump 21 and the valve 24, the valve 24, the first cylinder 12 and the second cylinder 13 are connected by hydraulic piping.

Here, the rotation sensor 23 includes an encoder, and outputs a pulse signal according to the number of rotations of the motor 22, which is transmitted to the control device 5. In addition, since the pump 21 and the motor 22 rotate integrally, the pump 21 may be provided with a rotation sensor 23 for detecting the number of rotations. In this case, the height detection can be performed in the same manner as described later. it can.
The valve 24 allows the hydraulic oil to flow from the pump 21 to both cylinders and prohibits the reverse flow. The valve 24 also allows the bidirectional flow between the pump 21 and both cylinders. It is a solenoid valve that can be switched between. When the solenoid provided in the valve 24 is energized by the control device 5, the position is switched to the lowered position, and when the excitation is stopped, the spring provided in the valve 24 returns to the raised position.

  When the pump 21 is driven forward by the motor 22, the hydraulic oil is sucked from the tank 20 and discharged toward the valve 24. The discharged hydraulic oil is supplied to both cylinders through the valve 24. Here, due to the difference in load applied to the first cylinder 12 and the second cylinder 13, first, the hydraulic oil is preferentially supplied to the first cylinder 12, and when it cannot be supplied to the first cylinder 12, the hydraulic oil is supplied to the second cylinder 13. The That is, in the state where the second cylinder 13 is shortened to the shortest, hydraulic oil is supplied to the first cylinder 12 and extends, and in the state where the first cylinder 12 is fully extended, the hydraulic oil is supplied to the second cylinder 13 and extends.

  On the other hand, when the forward drive of the pump 21 is stopped while the valve 24 is in the lowered position, the hydraulic oil from both cylinders flows into the pump 21 through the valve 24 and the pump 21 is reversed. Here, due to the difference in load applied to the first cylinder 12 and the second cylinder 13, first, the hydraulic oil is recovered with priority from the second cylinder 13, and when it cannot be recovered from the second cylinder 13, the hydraulic oil is recovered from the first cylinder 12. The That is, the hydraulic oil is recovered and shortened from the second cylinder 13 with the first cylinder 12 extended to the maximum, and the hydraulic oil is recovered and shortened from the first cylinder 12 with the second cylinder 13 shortened to the shortest.

  As shown in FIG. 4, the control device 5 controls the motor 22 through the inverter 6 and controls the valve 24 according to the operation of the up switch 17 and the down switch 17 </ b> B, and the lift of the cab 14. A lifting height calculation unit 52 for obtaining H.

  When the ascending switch 17 is operated, the elevating control unit 51 power-controls the motor 22 to rotate forward to drive the pump 21, and when the descending switch 17 </ b> B is operated, the valve 24 is excited to reverse the motor 22. Regenerative control. At the same time, when the ascending switch 17 or the descending switch 17B is operated, the elevation control unit 51 transmits a signal to that effect to the elevation calculation unit 52. Further, the lift control unit 51 is informed of the lift height H obtained by the lift calculation unit 52, and the lift control unit 51 responds to the number of revolutions of the motor 22, excitation to the valve 24, timing of excitation stop, etc. To control.

  The lift calculation unit 52 counts the pulse signal output from the rotation sensor 23 to calculate the lift height H, and counts the pulse signal output from the rotation sensor 19 to calculate the lift height H. A derivation unit 52B, a determination unit 52C that determines which one of the derivation unit 52A and the derivation unit 52B calculates the lift height H, and a storage unit 52D that stores the calculated lift height H and the like are provided. Therefore, the lift height H is required.

  As shown in FIG. 5, when the forklift is activated, the derivation unit 52A reads the lift height H and the coefficient K1 stored in the storage unit 52D, divides the lift height H by the coefficient K1, and at that time The total number of counts C1 is calculated. The derivation unit 52B reads the lift height H stored in the storage unit 52D, divides the lift height H by a preset coefficient K2, and calculates the total count C2 at that time (S1). Subsequently, the determination unit 52C determines whether or not the ascending switch 17A or the descending switch 17B is operated based on a signal from the ascending / descending control unit 51 (S2). It is determined whether or not 12 is operating (S3). That is, if the lift height H at that time is within the lift range due to the expansion and contraction of the first cylinder 12, it is determined that the first cylinder 12 is in operation, and the determination unit 52C selects the derivation unit 52A to the derivation unit 52A. The lift height H is calculated. That is, the derivation unit 52A counts the pulse signal from the rotation sensor 23, and updates the total count C1 by adding the amount of change ΔC1 (a positive value when rising and a negative value when falling) to the total count C1. (S4). Further, the derivation unit 52A calculates the lift height H by multiplying the total count C1 by the coefficient K1 (S5). The lift height H calculated in this way is stored in the storage unit 52 </ b> D and transmitted to the elevation control unit 51, and is used for controlling the motor 22 and the valve 24 in the elevation control unit 51.

  In S3, if the lift H at that time is not within the lift range due to the expansion and contraction of the first cylinder 12, it is determined that the first cylinder 12 is not operating and the second cylinder 13 is operating, and the determination unit 52C derives it. The part 52B is selected, and the deriving part 52B calculates the lift H. That is, as shown in FIG. 5, the derivation unit 52B counts the pulse signal from the rotation sensor 19, and adds the change amount ΔC2 (a positive value when rising and a negative value when falling) to the total count C2. The total count C2 is updated (S6). Further, the derivation unit 52B calculates the lift height H by multiplying the total count C2 by the coefficient K2 (S7). The lift height H calculated in this way is stored in the storage unit 52 </ b> D and transmitted to the elevation control unit 51, and is used for controlling the motor 22 and the valve 24 in the elevation control unit 51. Further, the lift height H is transmitted to the deriving unit 52A, and the deriving unit 52A calculates the coefficient K1 by dividing the change amount ΔH of the lift height H by the change amount ΔC1 of the total count C1 during that time (S8). The coefficient K1 is stored in the storage unit 52D, and is used for calculating the lift height H in the derivation unit 52A when the first cylinder 12 is operated next time.

  As is apparent from the above description, the coefficient K1 represents the relationship between the total number C1 of pulse signals counted from the rotation sensor 23 counted by the derivation unit 52A and the lift height H, and the coefficient K2 is the derivation unit. This represents the relationship between the total count C2 of pulse signals from the rotation sensor 19 counted at 52B and the lift height H.

According to such an embodiment, when the cab 14 moves up and down with respect to the inner mast 11 by the first cylinder 12, the lift height H of the cab 14 is calculated based on the output of the rotation sensor 23, and the second cylinder 13 9, when the middle mast 10 and the inner mast 11 move up and down, the lift height H of the cab 14 is calculated based on the output of the rotation sensor 19. Accordingly, the lift height H can be detected in the entire range in which the cab 14 moves up and down regardless of which cylinder is used to move up and down.
Further, since it is not necessary to provide a rotation sensor or the like on the inner mast 11 by connecting with the cab 14 so as to correspond to the raising and lowering of the cab 14 in the first cylinder 12, the deterioration of the visibility is suppressed. Therefore, the operator can easily confirm the front even when facing the steering handle 16 or the accelerator 18, and this embodiment does not increase the burden on driving.
Further, since the coefficient K1 is obtained from the lift H calculated during the raising / lowering of the second cylinder 13 and used for the calculation of the lifting height H during the raising / lowering of the first cylinder 12, the actual output of the rotation sensor 23 and The relationship of the lift height H can be reflected in the calculation of the lift height H, and the accuracy of the calculated lift height H can be improved.

In the above embodiment, the lift height H is calculated on the condition that either the ascending switch 17A or the descending switch 17B is operated, but instead of this, or in addition to this, The lift height H may be calculated on condition that the motor 22 is rotating.
In the above embodiment, it is determined whether the first cylinder 12 is operating or the second cylinder 13 is operating depending on whether or not the height H at that time is within the range of the height of expansion and contraction of the first cylinder 12. ing. However, the present invention is not limited to this, and any of the derivation units 52A and 52B may be selected based on other configurations.

1 is a rear perspective view of a forklift according to an embodiment of the present invention. 1 is a front perspective view of a forklift according to an embodiment of the present invention. It is the schematic of the lifting apparatus for cargo handling concerning the Example of this invention. It is a functional block diagram of the Example of this invention. It is a control flowchart of the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body 5 Control apparatus 51 Elevation control part 52 Lifting height calculation part 52A Derivation part 52B Derivation part 52C Determination part 52D Storage part 6 Inverter 8 Mast apparatus 9 Outer mast 10 Middle mast 11 Inner mast 12 First cylinder 13 Second cylinder 14 Driver's cab 17 Operation box 17A Up switch 17B Down switch 19 Rotation sensor 21 Pump 22 Motor 23 Rotation sensor

Claims (2)

First and second cylinders for raising and lowering the lifting tool are provided, hydraulic oil is supplied to the first and second cylinders by a pump, and the cylinders are extended to raise the lifting tool. A lifting device that collects hydraulic oil from the cylinder through the pump and shortens each cylinder to lower the lifting tool. The hydraulic oil is preferentially supplied to the first cylinder, and is prioritized from the second cylinder. A lifting device for detecting the lifting height of the lifting tool, wherein the lifting device is configured to collect hydraulic fluid, and is attached to the pump or a motor connected to the pump, and the number of rotations is increased. A rotation detection means for outputting a corresponding signal, a lifting detection means for outputting a signal corresponding to the lifting amount of the lifting tool, connected to the lifting tool, and the lifting and lowering based on the output of the rotation detection means. Fried ingredients First lifting height deriving means for calculating the lifting height, second lifting height deriving means for calculating the lifting height of the lifting tool based on the output of the lifting detection means, and the first and second lifting height deriving means Selecting means for selecting any one of the above, the selecting means selects the first lifting height deriving means when the first cylinder expands and contracts, and selects the above when the second cylinder expands and contracts. The second lifting height deriving means is selected, the lifting detection means is a wire type rotation sensor, and the lifting tool is supported by a fixed mast so as to be movable up and down, and the movable mast The movable cylinder is supported by the mast so as to be movable up and down, and the first cylinder is provided on the movable mast so that the movable platform is moved up and down relative to the movable mast by expansion and contraction. The cylinder of the fixed mast More and the fixed mast to be provided so that the movable mast is raised and lowered, the lifting detection means, the wire is connected to the movable mast with rotation sensor is provided on the fixed mast, the lifting amount of the movable mast The first lifting height deriving means calculates the lifting height of the movable base based on the output of the rotation detecting means, and the second lifting height deriving means Elevation of the movable base is calculated based on the output of the lift detection means and the height of the movable base relative to the movable mast with the first cylinder fully extended. Device height detection device.   The first lift height deriving means detects the rotation based on the output of the rotation detection means when the second cylinder expands and contracts and the lift calculated by the second lift height deriving means. A coefficient representing the relationship between the output of the means and the lift is calculated, and the lift is calculated based on the coefficient and the output of the rotation detection means when the first cylinder expands and contracts. The lifting height detecting device for an elevating device according to claim 1.

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