JP2008275073A - Power unit for lift and control method for lift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power unit for a lift which does not require provision of a sensor in the exterior of the power unit for detecting conditions of the lift, and enables a complete control of a gentle stop operation of a load-carrying platform within the power unit. <P>SOLUTION: The lift is provided with a lifting hydraulic-cylinder for driving up the load-carrying platform supported so as to be freely openable and liftable with respect to the vehicle. The lifting hydraulic-cylinder is operated gently as follows: at the time when the load-carrying platform is lowered from an upper limit to a prescribed lower position, the amount of return of hydraulic oil from the lifting hydraulic-cylinder to an oil tank 1 is measured by a flowmeter 20, and the amount of hydraulic-oil feeding to the lifting hydraulic-cylinder is measured by a tachometer 40 of a motor. In the lift-driving operation of the load-carrying platform, the point in time when the difference between the amount of return and the amount of feed of hydraulic oil has reached a prescribed value is taken as a slow-down operation-starting point, and thereafter operation of the lifting hydraulic-cylinder is effected gently. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power unit used in a lifting device that is mounted on a vehicle and loads and unloads cargo, and a method for controlling the lifting device.

  As a lifting device for loading and unloading mounted on the rear part of a lorry vehicle, a parallel link mechanism driven by a lifting hydraulic cylinder drives the loading platform (tailgate) up and down in a horizontal state. When the loading platform is not in use 2. Description of the Related Art A structure in which an open / close hydraulic cylinder is vertically closed from a horizontal state along a rear surface of a vehicle body is widely known. The lorry is run with the load receiving stand upright and closed.

  This type of lifting device will be described with reference to FIGS. A main arm mounting bracket 61, a sub arm mounting bracket 62, and a lifting cylinder mounting bracket 63 are fixedly integrated with the lifting device frame 60 fixed to the chassis 50 of the truck. The load receiving stand (tailgate) 70 integrally has a main arm mounting bracket 71 and a sub arm mounting bracket 72 on the rear end side.

  The main arm 80 and the sub arm 90 form a parallel link for driving the load receiving table 70 up and down, and one end of the main arm 80 is pivotally attached to the main arm mounting bracket 61 with a pin 81 (rotatably mounted). The other end is pivotally attached to the main arm mounting bracket 71 with a pin 82. One end of the sub arm 90 (in which an opening / closing hydraulic cylinder 95 is incorporated as will be described later with reference to FIG. 7) is pivotally attached to the sub arm mounting bracket 62 by a pin 91, and the other end is pivotally attached to the sub arm mounting bracket 72 by a pin 92. ing. An elevating hydraulic cylinder 55 is pivotally connected by pins 56 and 57 between the elevating cylinder mounting bracket 63 and the intermediate position of the main arm 80.

  The lifting hydraulic cylinder 55 is a single-acting hydraulic cylinder. In the contracted state, the load receiving base 70 is in a landing state as shown in FIG. In this way, the load receiving platform 70 is in the ascending limit position having the same height as the vehicle body floor of the truck.

  A part of the sub-arm 90 is constituted by an opening / closing hydraulic cylinder 95 of a single-acting hydraulic cylinder, and a constant length is maintained when the normal load receiving table 70 is raised and lowered. In the case of the operation of standing up and closing vertically along the rear surface of the vehicle body as shown in the solid line (c) of FIG. Also gets longer. In other words, when the open / close hydraulic cylinder 95 is in the extended state, the load receiving base 70 is closed vertically as shown by a solid line (c) in FIG. 7, and in the contracted state, it is opened in a horizontal state as shown in a virtual line (b) in FIG. . The rotation fulcrum of the load receiving table 70 is a pin 82 that is a pivot point on the front end side of the main arm 80.

  Note that the mounting positions of the lifting hydraulic cylinder and the opening / closing hydraulic cylinder are not limited to the configurations shown in FIGS. 6 and 7, and the lifting hydraulic cylinder can rotate either the main arm or the sub arm forming a parallel link. The opening / closing hydraulic cylinder only needs to rotate the load receiving table between the vertical state and the horizontal state.

  There is also a lifting device having a structure in which the opening and closing hydraulic cylinder is omitted and the load receiving table is manually opened and closed.

  As a control device for slowly starting and stopping the load receiving platform of the lifting device, there is the following Patent Document 1.

Japanese Patent Laid-Open No. 10-100776

  Patent document 1 aims at detecting the inclination angle of a load receiving stand with an inclination angle sensor, and making a load receiving stand always horizontal. In addition, an inclination angle sensor is also used for a slow stop of the opening / closing operation of the load receiving platform.

  In a conventional lifting device, the impact at the start and stop of the lifting hydraulic cylinder and the opening and closing hydraulic cylinder is large, and it is dangerous to lift and lower the loading platform, leading to instability of the load, and the loading platform The noise at the end of the last day was loud and caused complaints.

  In order to solve these problems, it is conceivable to detect the state of the load receiving table or the state of the parallel link mechanism for raising and lowering the load receiving table with an inclination angle sensor or a position sensor, but the arrangement of these sensors is parallel to the lifting device. The arrangement differs depending on the structure of the link mechanism, and it is necessary to devise a sensor arrangement (corresponding to each type of lifting device). In addition, these sensors are arranged outside the power unit that supplies hydraulic oil to the lifting hydraulic cylinder and the opening / closing hydraulic cylinder, and it is necessary to consider cooperation with a control circuit built in the power unit.

  In view of the above points, the present invention eliminates the need to provide a sensor or the like for detecting the state of the lifting device outside the power unit, and can complete the control of the slow stop operation of the load receiving platform within the power unit and ensure the operation. It is a first object to provide a power unit for use.

  Further, it is not necessary to provide a sensor for detecting the state of the lifting device outside the power unit, and it is possible to complete the control of the slow stop operation of the load receiving platform within the power unit and to provide a method of controlling the lifting device with reliable operation. Second purpose.

  Other objects and novel features of the present invention will be clarified in embodiments described later.

In order to achieve the above object, an aspect of the present invention provides a lifting device for use in a lifting device having a lifting hydraulic cylinder that drives a load receiving base supported to be openable / closable and liftable with respect to a vehicle. A power unit,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the lifting hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring a flow rate of hydraulic oil returning from the lifting hydraulic cylinder to the oil tank through the hydraulic circuit;
Rotation measuring means for measuring the number of rotations of the electric motor;
The hydraulic oil return amount to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position is obtained and stored from the measurement result of the flow rate measuring means, and the hydraulic cylinder for raising and lowering is stored. Control means for obtaining hydraulic oil delivery amount of the hydraulic pump from the measurement result of the rotation measuring means,
In the ascending drive operation of the cargo cradle, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the rotation speed of the electric motor is hereinafter referred to as the control means. It is characterized by lowering by.

Another aspect of the present invention is a power unit for a lifting device that is used in a lifting device having a lifting hydraulic cylinder that drives a load receiving base supported to be openable / closable and liftable with respect to a vehicle in a rising direction,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the lifting hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring a flow rate of hydraulic oil returning from the lifting hydraulic cylinder to the oil tank through the hydraulic circuit;
Rotation measuring means for measuring the number of rotations of the electric motor;
The hydraulic oil return amount to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position is obtained and stored from the measurement result of the flow rate measuring means, and the hydraulic cylinder for raising and lowering is stored. Control means for obtaining hydraulic oil delivery amount of the hydraulic pump from the measurement result of the rotation measuring means;
Flow rate adjusting means for reducing the flow rate of hydraulic oil to the lifting hydraulic cylinder,
In the ascending drive operation of the cargo cradle, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the starting point of the slow-down section is set as the starting point of the slowdown section, and the hydraulic cylinder for raising / lowering is thereafter performed by the flow rate adjusting means. It is characterized by restricting the flow rate of hydraulic oil to

Another aspect of the present invention is a power unit for a lifting device that is used in a lifting device having a lifting hydraulic cylinder that drives a load receiving base supported to be openable / closable and liftable with respect to a vehicle in a rising direction,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the lifting hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring the flow rate of hydraulic fluid sent to the lifting hydraulic cylinder and measuring the flow rate of hydraulic fluid returning from the lifting hydraulic cylinder into the oil tank;
The hydraulic oil return amount to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position is obtained and stored from the measurement result of the flow rate measuring means, and the hydraulic cylinder for raising and lowering is stored. A control means for obtaining a hydraulic oil delivery amount of the hydraulic pump from a measurement result of the flow rate measurement means,
In the ascending drive operation of the cargo cradle, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the rotation speed of the electric motor is hereinafter referred to as the control means. It is characterized by lowering by.

Another aspect of the present invention is a power unit for a lifting device that is used in a lifting device having a lifting hydraulic cylinder that drives a load receiving base supported to be openable / closable and liftable with respect to a vehicle in a rising direction,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the lifting hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring the flow rate of hydraulic fluid sent to the lifting hydraulic cylinder and measuring the flow rate of hydraulic fluid returning from the lifting hydraulic cylinder into the oil tank;
The hydraulic oil return amount to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position is obtained and stored from the measurement result of the flow rate measuring means, and the hydraulic cylinder for raising and lowering is stored. Control means for obtaining hydraulic oil delivery amount of the hydraulic pump from the measurement result of the flow rate measuring means;
Flow rate adjusting means for reducing the flow rate of hydraulic oil to the lifting hydraulic cylinder,
In the ascending drive operation of the cargo cradle, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the starting point of the slow-down section is set as the starting point of the slowdown section, and the hydraulic cylinder for raising / lowering is thereafter performed by the flow rate adjusting means It is characterized by restricting the flow rate of hydraulic oil to

Another aspect of the present invention includes an opening / closing hydraulic cylinder that closes a load receiving base supported to be openable / closable and elevating with respect to a vehicle from a horizontal state to a vertical state, and elevating and lowering to drive the load receiving base in an upward direction. A lifting device power unit for use in a lifting device having a hydraulic cylinder.
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the open / close hydraulic cylinder or the lift hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring a flow rate of the hydraulic oil returning from the opening / closing hydraulic cylinder or the elevating hydraulic cylinder to the oil tank through the hydraulic circuit;
Rotation measuring means for measuring the number of rotations of the electric motor;
The amount of hydraulic fluid returned from the open / close hydraulic cylinder to the oil tank when the load receiving table changes from a vertically closed state to a horizontally open state is obtained from the measurement result of the flow rate measuring means and stored. In addition, the hydraulic oil delivery amount of the hydraulic pump to the hydraulic cylinder for opening and closing is obtained from the measurement result of the rotation measuring means, and to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined descending position. A hydraulic fluid return amount obtained from the measurement result of the flow rate measuring means, and a control means for obtaining the hydraulic oil delivery amount of the hydraulic pump to the lifting hydraulic cylinder from the measurement result of the rotation measuring means; With
In the operation of closing the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the open / close hydraulic cylinder becomes a predetermined value, the start point of the slowdown section is set.
In the ascending drive operation of the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the elevating hydraulic cylinder becomes a predetermined value, the start point of the slowdown section is set, and each start point Thereafter, the number of rotations of the electric motor is reduced by the control means.

Another aspect of the present invention includes an opening / closing hydraulic cylinder that closes a load receiving base supported to be openable / closable and elevating with respect to a vehicle from a horizontal state to a vertical state, and elevating and lowering to drive the load receiving base in an upward direction. A lifting device power unit for use in a lifting device having a hydraulic cylinder.
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the open / close hydraulic cylinder or the lift hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring a flow rate of the hydraulic oil returning from the opening / closing hydraulic cylinder or the elevating hydraulic cylinder to the oil tank through the hydraulic circuit;
Rotation measuring means for measuring the number of rotations of the electric motor;
The amount of hydraulic fluid returned from the open / close hydraulic cylinder to the oil tank when the load receiving table changes from a vertically closed state to a horizontally open state is obtained from the measurement result of the flow rate measuring means and stored. In addition, the hydraulic oil delivery amount of the hydraulic pump to the hydraulic cylinder for opening and closing is obtained from the measurement result of the rotation measuring means, and to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined descending position. A hydraulic fluid return amount obtained from the measurement result of the flow rate measuring means, and a control means for obtaining the hydraulic oil delivery amount of the hydraulic pump to the lifting hydraulic cylinder from the measurement result of the rotation measuring means; ,
First flow rate adjusting means for restricting the flow rate of hydraulic oil to the open / close hydraulic cylinder;
Second flow rate adjusting means for reducing the flow rate of hydraulic oil to the lifting hydraulic cylinder;
In the operation of closing the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the open / close hydraulic cylinder reaches a predetermined value, the first flow rate is hereinafter referred to as the start point of the slowdown section. The flow of hydraulic oil to the opening / closing hydraulic cylinder is throttled by the adjusting means,
In the ascending drive operation of the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the elevating hydraulic cylinder becomes a predetermined value, the starting point of the slow-down section is referred to as the second below. A flow rate adjusting means restricts the flow rate of the hydraulic oil to the lifting hydraulic cylinder.

Another aspect of the present invention is a method for controlling a lifting device having a lifting hydraulic cylinder that drives a load receiving base supported to be openable / closable and liftable with respect to a vehicle in a rising direction,
Measures the amount of hydraulic oil returned from the lifting hydraulic cylinder to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position, and measures the amount of hydraulic oil delivered to the lifting hydraulic cylinder do it,
In the ascending drive operation of the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the operation of the elevating hydraulic cylinder is slowed down thereafter as a starting point of the slow-down section. It is characterized by doing.

Another aspect of the present invention includes an opening / closing hydraulic cylinder that closes a load receiving base supported to be openable / closable and elevating with respect to a vehicle from a horizontal state to a vertical state, and elevating and lowering to drive the load receiving base in an upward direction. A control method of a lifting device having a hydraulic cylinder for use,
Measures the amount of hydraulic fluid returned from the open / close hydraulic cylinder to the oil tank and sends the hydraulic oil to the open / close hydraulic cylinder when the load receiving platform changes from a vertically closed state to a horizontal open state. And measuring the amount of hydraulic fluid returned from the lifting hydraulic cylinder to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position and actuating the lifting hydraulic cylinder Measure the oil delivery amount,
When the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the open / close hydraulic cylinder reaches a predetermined value in the operation of closing the cargo cradle, the opening / closing hydraulic pressure is hereinafter referred to as a start point of the slowdown section. Slow down the cylinder movement,
In the ascending drive operation of the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the lifting hydraulic cylinder becomes a predetermined value, the starting point of the slow-down section is referred to as the lifting and lowering operation thereafter. It is characterized by slowing the operation of the hydraulic cylinder.

  According to the present invention, the state of the load receiving platform of the lifting device can be known by the measuring means in the power unit such as the flow rate measuring means for measuring the flow rate of the hydraulic oil, and the measurement result of the measuring means is used by using the measurement result of the measuring means. The starting point of the slowdown section for slow stop can be determined. For this reason, it is not necessary to provide a sensor for directly detecting the state of the cargo cradle outside the power unit, and the control can be completed inside the power unit.

  In addition, the series of operations in the lifting and unloading operation of the lifting device always uses the fact that both the opening and closing operations and the lifting operation start from the opening or lowering of the cargo cradle (tailgate). By measuring the amount of oil in the cylinder from the difference from the hydraulic oil delivery amount during the raising process, the start point of the slowdown section can be set before the receiving stand stop point, and the slow stop operation can be executed reliably. The impact at the stopping point (when hitting the vehicle body) can be reduced.

  Hereinafter, as a best mode for carrying out the present invention, an embodiment of a power unit for a lifting device and a control method for the lifting device will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 shows Embodiment 1 of the present invention. The lifting device power unit shown in FIG. 1 sucks up the oil tank 1 and the hydraulic oil in the oil tank 1 and lifts the lifting device illustrated in FIGS. 6 and 7 through the lifting port or the open / close port of the hydraulic circuit. The hydraulic pump P that supplies hydraulic oil to the cylinder 55 or the open / close hydraulic cylinder 95, the electric motor M that drives the pump P, and opens when the discharge side of the pump P exceeds a certain pressure. It has a relief valve (safety valve) 2 that returns to the inside, electromagnetic switching valves 11, 12, and 13, a check valve 15, a flow rate adjusting valve 16, and a flow meter 20 as a flow rate measuring means. The return of hydraulic fluid from the lifting hydraulic cylinder 55, the opening / closing hydraulic cylinder 95, and the relief valve 2 to the oil tank 1 all passes through the flow meter 20. The flow meter 20 has a structure that outputs a flow rate as a rotation speed.

  The motor M is a direct current motor (direct current motor) and has a property that the number of motor rotations is proportional to the applied voltage. In order to control the DC motor M, the lifting device power unit is provided with a control circuit 30 with a built-in CPU as a control means and a tachometer 40 as a rotation measuring means for measuring the rotation speed of the motor. The control circuit 30 performs the slow start control of FIG. 5 (A) and the slow down control of FIG. 5 (B) regarding the operations of the lifting hydraulic cylinder 55 and the opening / closing hydraulic cylinder 95. The motor voltage at this time is changed by performing PWM (pulse width control) in the control circuit 30 (gradual increase and decrease). In order to determine the start point of the slow-down section of FIG. 5B, the flow rate of the flow meter as the flow rate measurement value of the flow meter 20 and the motor rotation rate as the measurement value of the tachometer 40 are supplied to the control circuit 30. Have been entered.

  Next, the operation of the first embodiment will be described in the case where the lifting device of FIGS. 6 and 7 is driven. Since the load receiving table 70 of the lifting device is always in the vertically closed state when the lorry is traveling, the loading / unloading work of the lifting device is always the operation to open horizontally from the state in which the load receiving table 70 is closed vertically (closed to open). ). This opening operation is performed by exciting and opening the electromagnetic switching valves 12 and 13 with an opening / closing operation switch (not shown) and returning the hydraulic oil from the opening / closing hydraulic cylinder 95 through the flow meter 20. The number of revolutions of the flow meter 20 (total number of revolutions during the period from the vertical to the horizontal opening) is the oil tank 1 from the open / close hydraulic cylinder 95 when the load receiving base 70 changes from the vertical closed state to the horizontal open state. Therefore, the control circuit 30 calculates and stores the return amount of the hydraulic oil from the measurement value of the flow meter 20.

  Then, in order to perform cargo handling work between the vehicle body floor surface and the platform such as the ground or a warehouse, the load receiving platform 70 at the same height (ascending limit position) as the vehicle body floor surface is defined by the ground or platform height. Lowered to a predetermined lowered position. This lowering operation is performed by exciting and opening the electromagnetic switching valves 11 and 13 by a lifting operation switch (not shown) and returning the hydraulic oil from the lifting hydraulic cylinder 55 through the flow meter 20. The rotational speed of the flow meter 20 (total rotational speed during the lowering operation period) is the hydraulic oil from the lifting hydraulic cylinder 55 to the oil tank 1 when the load receiving platform 70 reaches the predetermined lowering position from the ascent end position and stops. Since it is directly proportional to the return amount, the control circuit 30 calculates and stores the return amount of the hydraulic oil from the measured value of the flow meter 20.

  Whether the measured value of the flow meter 20 corresponds to the open / close hydraulic cylinder 95 or the lift hydraulic cylinder 55 is determined by a signal (electromagnetic switching valve 11) by an open / close operation switch or a lift operation switch (not shown). , 12, 13) is supplied to the control circuit 30, and can be performed on the control circuit 30 side.

  The ascending drive operation for raising the load receiving platform 70 from the predetermined descending position defined by the ground or platform height to the ascending limit position excites the electromagnetic switching valve 11 with the elevation operation switch and opens the pump P with the motor M. Is driven by pumping up hydraulic oil from the oil tank 1 and sending it to the lifting hydraulic cylinder 55. Here, the amount of hydraulic oil delivered from the pump P to the lifting hydraulic cylinder 55 is directly proportional to the rotational speed of the motor M. In other words, the rotation speed of the tachometer 40 (cumulative rotation speed during the ascending drive operation) is directly proportional to the amount of hydraulic oil delivered to the elevating hydraulic cylinder 55 during the ascending drive operation. The hydraulic oil delivery amount is calculated from time to time.

  In this ascending drive operation, as shown in FIG. 5 (A), a slow start period is set for a while from the ascending start point (time is set by a timer), and the load receiving platform 70 is gently lowered by gradually increasing the motor voltage. Raise it. After the slow start section elapses, the load receiving platform 70 rises at a normal speed, but after reaching the start point of the slow down section in FIG. 5B set before the ascent end position of the load receiving platform 70, the motor voltage is increased. Is gradually lowered to raise the load receiving table 70 to the ascending limit position.

  Here, the starting point of the slow-down section in FIG. 5B is the measured value of the tachometer 40 from the amount of hydraulic oil returned from the lifting hydraulic cylinder 55 to the oil tank 1 stored during the lowering operation. This is the time when the value obtained by subtracting the calculated hydraulic oil delivery amount becomes a predetermined small value (this indicates that the load receiving base 70 has approached the ascent end position, which is the stop point).

  In the operation of closing the load receiving stand 70 in the ascending limit position by rotating it vertically from the horizontal state for traveling of the truck, the electromagnetic switching valve 12 is excited and opened by the opening / closing operation switch, and the pump P is driven by the motor M. , And the hydraulic oil is pumped from the oil tank 1 and delivered to the open / close hydraulic cylinder 95. Here, the amount of hydraulic oil delivered from the pump P to the open / close hydraulic cylinder 95 is directly proportional to the rotational speed of the motor M. That is, the rotation speed of the tachometer 40 (cumulative rotation speed during the closing operation) is directly proportional to the amount of hydraulic oil sent to the opening / closing hydraulic cylinder 95 during the closing operation. The amount of hydraulic oil delivered is calculated from time to time.

  In this closing operation, as shown in FIG. 5A, a slow start period is set for a while from the rotation start point (time is set by a timer), and the load receiving base 70 is gently lowered by gradually increasing the motor voltage. Rotate. After the slow start section elapses, the cradle 70 rotates vertically at a normal speed, but the slow down section of FIG. 5B set in front of the vertical position that is the stop point of the cradle 70. After reaching the start point, the load receiving base 70 is gently rotated by gradually decreasing the motor voltage to reach the vertical closed position.

  Here, the starting point of the slow-down section in FIG. 5B is the value measured by the tachometer 40 from the amount of hydraulic oil returned from the open / close hydraulic cylinder 95 to the oil tank 1 stored during the opening operation. The value obtained by subtracting the calculated hydraulic oil delivery amount becomes a predetermined small value (this indicates that the load receiving base 70 has approached a stop position where the load receiving base 70 rotates vertically).

  According to the first embodiment, the following effects can be obtained.

(1) The flow meter 20 that measures the flow rate of hydraulic oil and the tachometer 40 that detects the rotation of the electric motor M that rotationally drives the hydraulic pump P are measuring means arranged in the power unit, and these are used for the lifting device. The state of the load receiving platform 70 can be known, and the start point of the slow-down section for the slow stop during the ascending drive operation and closing operation of the load receiving platform 70 using the measurement results of the flow meter 20 and the tachometer 40 can be obtained. Can be determined. For this reason, it is not necessary to provide a sensor for directly detecting the state of the cargo cradle outside the power unit, and the control can be completed inside the power unit.

(2) The series of operations in the loading / unloading operation of the lifting / lowering device always uses the fact that both the opening / closing operation and the lifting / lowering operation start from the lowering of the load receiving base 70. In the process of lowering the load receiving base, The amount of oil in the cylinder can be measured from the difference from the hydraulic oil delivery amount of the cylinder, and the start point of the slow-down section can be set before the load rest stop point, so that the slow stop operation can be executed reliably. Can reduce the impact (when hitting the car body).

Embodiment 2. FIG.
FIG. 2 shows a second embodiment of the present invention. In the lifting device power unit shown in FIG. 2, the flow meter 20 is inserted between the electromagnetic switching valve 11 and the lifting port to return the hydraulic fluid and the hydraulic fluid to the lifting hydraulic cylinder 55. A total of 20 is measured. A tachometer that measures the number of revolutions of the electric motor M that rotationally drives the hydraulic pump P is not used. Other configurations are the same as those of the first embodiment.

  The operation of the second embodiment will be described in the case where the lifting device of FIGS. 6 and 7 is driven. The electromagnetic switching valves 12 and 13 are excited and opened by an opening / closing operation switch (not shown), the hydraulic oil from the opening / closing hydraulic cylinder 95 is returned to the oil tank 1, and the load receiving platform 70 is changed from a vertically closed state to a horizontally opened state. To do.

  Then, in order to perform cargo handling work between the vehicle body floor surface and the platform such as the ground or a warehouse, the load receiving platform 70 at the same height (ascending limit position) as the vehicle body floor surface is defined by the ground or platform height. Lowered to a predetermined lowered position. This lowering operation is performed by exciting and opening the electromagnetic switching valves 11 and 13 by a lifting operation switch (not shown) and returning the hydraulic oil from the lifting hydraulic cylinder 55 through the flow meter 20. The rotational speed of the flow meter 20 (the total rotational speed during the lowering operation period) is the hydraulic oil from the lifting hydraulic cylinder 55 to the oil tank 1 when the load receiving platform 70 reaches the predetermined lowering position from the ascent end position and stops. Since it is directly proportional to the return amount, the control circuit 30 calculates and stores the return amount of the hydraulic oil from the measured value of the flow meter 20.

  The ascending drive operation for raising the load receiving platform 70 from the predetermined descending position defined by the ground or platform height to the ascending limit position excites the electromagnetic switching valve 11 with the elevation operation switch and opens the pump P with the motor M. , And the hydraulic oil is pumped up from the oil tank 1 and sent to the lifting hydraulic cylinder 55 through the flow meter 20. Here, the amount of hydraulic oil delivered from the pump P to the lifting hydraulic cylinder 55 is the rotational speed of the flow meter 20 (the total rotational speed during the upward driving operation) was sent to the lifting hydraulic cylinder 55 during the upward driving operation. Since it is directly proportional to the hydraulic fluid delivery amount, the control circuit 30 calculates the hydraulic fluid delivery amount from time to time based on the measurement value of the flow meter 20.

  In this case as well, slow start control in the slow start section and slow down control in the slow down section are performed in the same manner as in the first embodiment, but the start point of the slow down section is determined only by the measured value of the flow meter 20.

  That is, the starting point of the slow-down section in FIG. 5B is based on the measured value of the flow meter 20 from the amount of hydraulic oil returned from the lifting hydraulic cylinder 55 to the oil tank 1 stored during the lowering operation. This is a time when the value obtained by subtracting the calculated hydraulic oil delivery amount becomes a predetermined small value (this indicates that the load receiving base 70 has approached the ascent end position).

  According to the second embodiment, there is an advantage that the slow-down control of the lifting hydraulic cylinder 55 can be performed only by the measured value of the flow meter 20. Other functions and effects are the same as those of the first embodiment.

  In addition, if a flow meter is inserted between the electromagnetic switching valve 12 and the open / close port to measure the return of hydraulic oil and the delivery of hydraulic oil to the open / close hydraulic cylinder, the slow down control of the open / close hydraulic cylinder is possible as well. It is.

Embodiment 3 FIG.
FIG. 3 shows a third embodiment of the present invention. In the lifting device power unit shown in FIG. 3, the arrangement of the flow meter 20 and the tachometer 40 is the same as that of the first embodiment, and the electromagnetic switching valve 25 for slow-down control and the flow rate as the flow rate adjusting means. A throttle valve 26 is connected in parallel to the electromagnetic switching valve 11. Other configurations are the same as those of the first embodiment.

  In this case, the slow start control in the slow start section and the slow down control in the slow down section are performed by reducing the hydraulic oil flow rate of the lifting hydraulic cylinder 55. The determination of the start point of the slow-down section is the same as in the first embodiment, but instead of performing the slow-down control by the PWM control of the electric motor M, the flow restrictor 26 serving as the flow rate adjusting means is connected to the lifting hydraulic cylinder 55. This is done by inserting it into the hydraulic oil delivery path. That is, after the start point of the slow-down section, the electromagnetic switching valve 11 is closed (off), the electromagnetic switching valve 25 is opened (on), and the lift hydraulic cylinder 55 is connected to the flow restrictor 26 and the electromagnetic switching valve 25. By sending the hydraulic oil, the movement of the lifting hydraulic cylinder 55 is slowed down.

  Note that slow down control can be performed for the open / close hydraulic cylinder 95 by using the same electromagnetic switching valve and flow restrictor.

Embodiment 4 FIG.
FIG. 4 shows a fourth embodiment of the present invention. In the lifting device power unit shown in FIG. 4, the arrangement of the flow meter 20 is the same as that of the second embodiment, and further includes an electromagnetic switching valve 25 for slow-down control and a flow restrictor 26 as a flow adjusting means. Are connected to the electromagnetic switching valve 11 in parallel. Other configurations are the same as those of the second embodiment.

  In this case, the slow start control in the slow start section and the slow down control in the slow down section are performed by reducing the hydraulic oil flow rate of the lifting hydraulic cylinder 55. The determination of the start point of the slow-down section is the same as in the second embodiment, but instead of performing the slow-down control by the PWM control of the electric motor M, the flow restrictor 26 serving as the flow rate adjusting means is connected to the lifting hydraulic cylinder 55. This is done by inserting it into the hydraulic oil delivery path. That is, after the start point of the slow-down zone, the electromagnetic switching valve 11 is closed, the electromagnetic switching valve 25 is opened, and hydraulic fluid is sent to the lifting hydraulic cylinder 55 through the flow restrictor 26 and the electromagnetic switching valve 25. Therefore, the movement of the lifting hydraulic cylinder 55 is slowed down.

  Although the embodiments of the present invention have been described above, it will be obvious to those skilled in the art that the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a hydraulic circuit diagram showing a first embodiment of a lifting apparatus power unit and a lifting apparatus control method according to the present invention. FIG. 3 is a hydraulic circuit diagram showing a second embodiment. FIG. 6 is a hydraulic circuit diagram showing a third embodiment. FIG. 6 is a hydraulic circuit diagram showing a fourth embodiment. It is explanatory drawing of the slow start and slow down control in Embodiment 1,2. It is an example of the raising / lowering apparatus, Comprising: It is a side view which shows the raising / lowering operation | movement of a load receiving stand. It is an example of the raising / lowering apparatus, Comprising: It is a side view which shows the opening / closing operation | movement of a receiving stand.

Explanation of symbols

1 Oil tank 2 Relief valve 11, 12, 13, 25 Electromagnetic switching valve
DESCRIPTION OF SYMBOLS 20 Flowmeter 26 Flow throttle valve 30 Control circuit 40 Tachometer 50 Chassis 55 Lifting hydraulic cylinder 60 Lifting device frame 70 Loading stand 80 Main arm 90 Sub arm 95 Opening / closing hydraulic cylinder M Electric motor P Hydraulic pump

Claims (8)

A lifting device power unit used in a lifting device having a lifting hydraulic cylinder that drives a load receiving table supported to be openable and closable and liftable with respect to a vehicle,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the lifting hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring a flow rate of hydraulic oil returning from the lifting hydraulic cylinder to the oil tank through the hydraulic circuit;
Rotation measuring means for measuring the number of rotations of the electric motor;
The hydraulic oil return amount to the oil tank when the load receiving platform is lowered from the ascent end position to a predetermined lowering position is obtained from the measurement result of the flow rate measuring means, and is stored. Control means for obtaining hydraulic oil delivery amount of the hydraulic pump from the measurement result of the rotation measuring means,
In the ascending drive operation of the cargo cradle, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the starting point of the slowdown section is set as the starting point of the slow-down section, and thereafter the rotational speed of the electric motor is controlled by the control means. A power unit for a lifting device, wherein the power unit is lowered at a lower position. A lifting device power unit used in a lifting device having a lifting hydraulic cylinder that drives a load receiving table supported to be openable and closable and liftable with respect to a vehicle,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the lifting hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring a flow rate of hydraulic oil returning from the lifting hydraulic cylinder to the oil tank through the hydraulic circuit;
Rotation measuring means for measuring the number of rotations of the electric motor;
The hydraulic oil return amount to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position is obtained and stored from the measurement result of the flow rate measuring means, and the hydraulic cylinder for raising and lowering is stored. Control means for obtaining hydraulic oil delivery amount of the hydraulic pump from the measurement result of the rotation measuring means;
Flow rate adjusting means for reducing the flow rate of hydraulic oil to the lifting hydraulic cylinder,
In the ascending drive operation of the cargo cradle, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the starting point of the slow-down section is set as the starting point of the slowdown section, and the hydraulic cylinder for raising / lowering is thereafter performed by the flow rate adjusting means A power unit for a lifting device, characterized in that the flow rate of hydraulic oil to the head is reduced. A lifting device power unit used in a lifting device having a lifting hydraulic cylinder that drives a load receiving table supported to be openable and closable and liftable with respect to a vehicle,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the lifting hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring the flow rate of hydraulic fluid sent to the lifting hydraulic cylinder and measuring the flow rate of hydraulic fluid returning from the lifting hydraulic cylinder into the oil tank;
The hydraulic oil return amount to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position is obtained and stored from the measurement result of the flow rate measuring means, and the hydraulic cylinder for raising and lowering is stored. A control means for obtaining a hydraulic oil delivery amount of the hydraulic pump from a measurement result of the flow rate measurement means,
In the ascending drive operation of the cargo cradle, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the rotation speed of the electric motor is hereinafter referred to as the control means. A power unit for a lifting device, wherein the power unit is lowered at a lower position. A lifting device power unit used in a lifting device having a lifting hydraulic cylinder that drives a load receiving table supported to be openable and closable and liftable with respect to a vehicle,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the lifting hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring the flow rate of hydraulic fluid sent to the lifting hydraulic cylinder and measuring the flow rate of hydraulic fluid returning from the lifting hydraulic cylinder into the oil tank;
The hydraulic oil return amount to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position is obtained and stored from the measurement result of the flow rate measuring means, and the hydraulic cylinder for raising and lowering is stored. Control means for obtaining hydraulic oil delivery amount of the hydraulic pump from the measurement result of the flow rate measuring means;
Flow rate adjusting means for reducing the flow rate of hydraulic oil to the lifting hydraulic cylinder,
In the ascending drive operation of the cargo cradle, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the starting point of the slow-down section is set as the starting point of the slowdown section, and the hydraulic cylinder for raising / lowering is thereafter performed by the flow rate adjusting means A power unit for a lifting device, characterized in that the flow rate of hydraulic oil to the head is reduced. An elevating apparatus having an opening / closing hydraulic cylinder for closing a load receiving base supported to be openable / closable and elevating with respect to a vehicle from a horizontal state to a vertical state, and an elevating hydraulic cylinder for driving the load receiving base in an upward direction. A lifting unit power unit to be used,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the open / close hydraulic cylinder or the lift hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring a flow rate of the hydraulic oil returning from the opening / closing hydraulic cylinder or the elevating hydraulic cylinder to the oil tank through the hydraulic circuit;
Rotation measuring means for measuring the number of rotations of the electric motor;
The amount of hydraulic fluid returned from the open / close hydraulic cylinder to the oil tank when the load receiving table changes from a vertically closed state to a horizontally open state is obtained from the measurement result of the flow rate measuring means and stored. In addition, the hydraulic oil delivery amount of the hydraulic pump to the hydraulic cylinder for opening and closing is obtained from the measurement result of the rotation measuring means, and to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined descending position. A hydraulic fluid return amount obtained from the measurement result of the flow rate measuring means, and a control means for obtaining the hydraulic oil delivery amount of the hydraulic pump to the lifting hydraulic cylinder from the measurement result of the rotation measuring means; With
In the operation of closing the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the open / close hydraulic cylinder becomes a predetermined value, the start point of the slowdown section is set.
In the ascending drive operation of the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the elevating hydraulic cylinder becomes a predetermined value, the start point of the slowdown section is set, and each start point Thereafter, the power unit for the lifting device is characterized in that the number of rotations of the electric motor is reduced by the control means. An elevating apparatus having an opening / closing hydraulic cylinder for closing a load receiving base supported to be openable / closable and elevating with respect to a vehicle from a horizontal state to a vertical state, and an elevating hydraulic cylinder for driving the load receiving base in an upward direction. A lifting unit power unit to be used,
An oil tank,
A hydraulic pump that sucks up the hydraulic oil in the oil tank and supplies the hydraulic oil to the open / close hydraulic cylinder or the lift hydraulic cylinder through a hydraulic circuit;
An electric motor for rotationally driving the hydraulic pump;
A flow rate measuring means for measuring a flow rate of the hydraulic oil returning from the opening / closing hydraulic cylinder or the elevating hydraulic cylinder to the oil tank through the hydraulic circuit;
Rotation measuring means for measuring the number of rotations of the electric motor;
The amount of hydraulic fluid returned from the open / close hydraulic cylinder to the oil tank when the load receiving table changes from a vertically closed state to a horizontally open state is obtained from the measurement result of the flow rate measuring means and stored. In addition, the hydraulic oil delivery amount of the hydraulic pump to the hydraulic cylinder for opening and closing is obtained from the measurement result of the rotation measuring means, and to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined descending position. A hydraulic fluid return amount obtained from the measurement result of the flow rate measuring means, and a control means for obtaining the hydraulic oil delivery amount of the hydraulic pump to the lifting hydraulic cylinder from the measurement result of the rotation measuring means; ,
First flow rate adjusting means for restricting the flow rate of hydraulic oil to the open / close hydraulic cylinder;
Second flow rate adjusting means for reducing the flow rate of hydraulic oil to the lifting hydraulic cylinder;
In the operation of closing the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the open / close hydraulic cylinder reaches a predetermined value, the first flow rate is hereinafter referred to as the start point of the slowdown section. The flow of hydraulic oil to the opening / closing hydraulic cylinder is throttled by the adjusting means,
In the ascending drive operation of the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the elevating hydraulic cylinder becomes a predetermined value, the starting point of the slow-down section is referred to as the second below. A power unit for a lifting device, characterized in that the flow rate of hydraulic oil to the lifting hydraulic cylinder is reduced by a flow rate adjusting means. A control method for an elevating device having an elevating hydraulic cylinder for driving a load receiving base supported to be openable and closable with respect to a vehicle in a rising direction
Measures the amount of hydraulic oil returned from the lifting hydraulic cylinder to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position, and measures the amount of hydraulic oil delivered to the lifting hydraulic cylinder do it,
In the ascending drive operation of the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount reaches a predetermined value, the operation of the elevating hydraulic cylinder is slowed down thereafter as a starting point of the slow-down section. A control method for a lifting device. An elevating apparatus having an opening / closing hydraulic cylinder for closing a load receiving base supported to be openable / closable and elevating with respect to a vehicle from a horizontal state to a vertical state, and an elevating hydraulic cylinder for driving the load receiving base in an upward direction. A control method,
Measures the amount of hydraulic fluid returned from the open / close hydraulic cylinder to the oil tank and sends the hydraulic oil to the open / close hydraulic cylinder when the load receiving platform changes from a vertically closed state to a horizontal open state. And measuring the amount of hydraulic fluid returned from the lifting hydraulic cylinder to the oil tank when the load receiving platform is lowered from the ascending limit position to a predetermined lowering position and actuating the lifting hydraulic cylinder Measure the oil delivery amount,
When the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the open / close hydraulic cylinder reaches a predetermined value in the operation of closing the cargo cradle, the opening / closing hydraulic pressure is hereinafter referred to as a start point of the slowdown section. Slow down the cylinder movement,
In the ascending drive operation of the load receiving platform, when the difference between the hydraulic oil return amount and the hydraulic oil delivery amount for the lifting hydraulic cylinder becomes a predetermined value, the starting point of the slow-down section is referred to as the lifting and lowering operation thereafter. A control method for a lifting device, characterized in that the operation of a hydraulic cylinder is slowed down.

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