JPH0599734A - Weighing instrument with shock absorber - Google Patents

Abstract

PURPOSE:To obtain a weighing instrument with shock absorber which can exert a large shock absorbing ability without deteriorating its measurement accuracy. CONSTITUTION:In a standby state, a supporting table 10 is pushed up by means of a compression spring and a stage 1 is separated from load detecting device 7. When an object 9 to be measured is placed on the stage 1, a compressive force is applied to the first cylinder chamber of a cylinder device 12 through the table 10 and the working fluid in the first cylinder chamber is pushed out by a flow rate decided by a flow metering valve 16. As a result, the table 10 slowly descends toward the device 7 and the stage 1 is loaded onto the device 7. When a control section 23 detects the in-measurement state, a working fluid is forcibly supplied to the second cylinder chamber of the device 12 and the table 10 is lowered to a position at which the table 10 does not come into contact with the stage 1. When the section 23 sets a change-over valve 15 to its third switched state thereafter, the working fluid is forcibly supplied to the first cylinder chamber by means of the pump and the stage 1 is quickly separated from the device 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weighing device having a shock absorbing function for protecting a load detecting device when a shock is applied to a mounting table.

[0002]

2. Description of the Related Art When an object to be measured is placed on a mounting table, if the object to be measured is thrown or thrown, the impact force directly acts on the load detecting device and the load detecting device is damaged.

Therefore, as shown in FIG. 5, it is possible to protect the load cell 4, which is a load detecting device, from an impact force by interposing a damper 3 between the mounting base 1 and the fixed base 2. Also,
As shown by the phantom lines in FIG. 4 without using such a damper 3, an auxiliary mount 6 is provided on the mount 1 via a cushion material 5, and an object to be measured is mounted on the auxiliary mount 6. The load cell 4 can be placed to protect it from impact.

[0004]

Although the one using the damper 3 can be expected to have a greater cushioning capacity than the one using the cushion material 5, a part of the load is always supported by the damper 3. Therefore, there is a problem that the measurement accuracy is lowered.

An object of the present invention is to provide a weighing device with a shock absorbing device, which is expected to have a large shock absorbing capacity and which is not accompanied by a decrease in measurement accuracy.

[0006]

According to another aspect of the present invention, there is provided a load detecting device for a load measuring apparatus having a shock absorbing device, wherein a compression spring is provided between a supporting base on which a mounting base is mounted and a fixed side. A cylinder device is installed between the support base and the fixed side in parallel with the compression spring, and is compressed by a load from a mounting base of both cylinder chambers of the cylinder device. In the first switching state in which both the cylinder chamber and the second cylinder chamber on the side opposite to the first cylinder chamber are communicated with the tank of the working fluid, and the first cylinder chamber is communicated with the tank to communicate with the tank. Acts in a second switching state in which the second cylinder chamber is connected to the discharge port and in a third switching state in which the second cylinder chamber is connected to the tank and the first cylinder chamber is connected to the discharge port of the pump. A switching valve for switching the fluid flow path is provided to A throttle valve is provided in the discharge passage of the working fluid from the binder chamber or the suction passage of the working fluid to the second cylinder chamber, and is arranged in parallel with the throttle valve in a direction that does not hinder the suction of the working fluid to the first cylinder chamber. Provide a connected check valve,
During standby, the switching valve is set to the first switching state, and when the detection state of the load detected by the load detecting device exceeds the specified weight, the switching valve is set to the second switching state, and then the switching valve is set to the first switching state. It is characterized in that a control unit for switching to the switching state of No. 3 is provided.

[0007]

According to this structure, the support base is pushed up by the compression spring and the mounting base is separated from the load detecting device until the control section detects the measuring state.

When the object to be measured is placed on the table, a compressive force acts on the first cylinder chamber of the cylinder device via the support table, and the first cylinder chamber is flowed at a unit time determined by the throttle valve. Of the working fluid is pushed out, the support base is gently lowered toward the load detection device, and the mounting base is loaded on the load detection device.

When the platform is loaded on the load detecting device and the control section detects the measuring state, the switching valve enters the second switching state, and the working fluid is pushed from the pump into the second cylinder chamber to cause the cylinder to move. The stem of the device is retracted to further compress the compression spring and lower the support to a position where it does not contact the platform. The reading of the weight value is carried out in this state, and when the control unit subsequently puts the switching valve in the third switching state, the first
The working fluid is sent by a pump to the cylinder chamber, and the platform is rapidly separated from the load detection device.

[0010]

Embodiments of the present invention will be described below with reference to FIGS. The weighing device with a shock absorbing device of the present invention is configured as shown in FIG. A platform scale 7 as a load detection device is mounted on a fixed side 8, and a platform 1 on which an object to be measured 9 is mounted is a support platform as shown in FIG. 1 in a standby state.
It is lifted from the platform scale 7 by 10.

The support base 10 is pushed up by a compression spring 11, and a cylinder device 12 is interposed in parallel with the compression spring 11. Of the two cylinder chambers of the cylinder device 12, the cylinder chamber compressed by the load from the mounting table 1 is referred to as a first cylinder chamber a, and the cylinder chamber opposite to the first cylinder chamber a is referred to as a second cylinder chamber b. Then, the first cylinder chambers a of the plurality of cylinder devices 12 are connected to each other by the first pipe 13, and the second cylinder chambers b are connected to each other by the second pipe 14.

The flow of the working fluid in the first and second pipes 13 and 14 is selected by a return three-position five-way type solenoid valve 15 as a switching valve. Switching is performed based on the weighing signal S.

[0013] Incidentally, the total upward force generated by the compression spring 11 "F", the transom weight of the platform 1 "W ₀
Is set to “F> W ₀ ”, and in the standby state before the object to be measured is loaded on the platform 1,
As shown in FIG.
Have been lifted from and separated. Here the support base 10
Is included in "W ₀ ".

In this standby state, the solenoid valve 15 is in the neutral position P0, and the first pipe 13 is provided with the throttle valve 16
And a tank 17 via a solenoid valve 15. Throttle valve
A check valve 19 is connected in parallel to 16 in a direction that prohibits the flow of the working fluid 18 from the first pipe 13 toward the tank 17. The second pipe 14 is connected to the tank 17 via a solenoid valve 15.

When the object to be measured 9 is loaded on the mounting table 1 in this standby state, the supporting base 10 is pushed down against the bias of the compression spring 11, and the stem 20 of the cylinder device 12 is moved to the first cylinder chamber. The working fluid in the first cylinder chamber a is gently returned to the tank 17 at a flow rate regulated by the throttle valve 16 via the pipe 21, and is then piped into the second cylinder chamber b.
The working fluid is sucked up from the tank 17 via the electromagnetic valve 15, the platform 1 is gently lowered onto the platform 7, and the platform 1 is loaded on the platform 7 as shown in FIG.

When the platform 1 is loaded on the platform scale 7 and the weight value of the platform scale gradually increases from the load "zero", and the control section 23 detects a measuring state in which the specified weight near the zero point is reached, the solenoid valve is activated.
15 is switched to the first position P1 shown in FIG.

When the solenoid valve 15 is switched to the first position P1, the working fluid is pushed from the pump 24 into the second cylinder chamber b through the second pipe 14 and resists the bias of the compression spring 11. Support base 10 slowly descends further,
Is separated from the platform 1 and the total load of the object 9 to be measured acts on the platform scale 7.

In this state, the balanced weight value of the platform scale 7 is taken as the measured value. Since the working fluid 18 is discharged to the tank 17 only at the speed regulated by the throttle valve 16 in this manner, even when the DUT 9 is roughly placed on the platform 1, the working fluid 18 is applied to the force application section of the platform scale 7. No impact force is applied, and the platform scale 7
Can be protected. Also, as shown in FIG.
Since the support base 10 is completely separated from the mounting base 1 and is not in contact when reading the weight value, high-precision measurement can be expected even though the buffer function is obtained as described above.

In this embodiment, when the control unit 23 detects that the weighing value of the platform scale 7 is balanced other than near the zero point, the solenoid valve 15 is activated by the solenoid valve 15 as shown in FIG. The second position P2 is switched to, as shown in FIG.

When the solenoid valve 15 is switched to the second position P2, the discharge port of the pump 24 is connected to the first pipe 13 via the solenoid valve 15 and the check valve 19, and the second pipe 14 is connected to the solenoid valve. 15
And the tank 17 through the pipe 22. Therefore,
The working fluid 18 is sent to the first cylinder chamber a by the pump 24, the support base 10 is rapidly raised, the platform 1 is lifted, and the platform 1 is separated from the platform scale 7.

The state where the platform 1 is lifted to the specified position and separated from the platform scale 7 is detected by the limit switch 25 shown in FIG. 1, and the control unit 23 reads the detection output of the limit switch 25 and When it is confirmed that 1 has risen to the specified position, the solenoid valve 15 is returned to the neutral position P0.

Therefore, the support base 10 rises faster than when it descends, the platform 1 is lifted from the platform scale 7 to return to the standby state shown in FIG. 1, and the next measurement can be performed early.
As the working fluid 18, it is preferable to use a liquid having an appropriate viscosity.

In the above embodiment, the detection output of the limit switch 25 is read and the solenoid valve 15 is returned from the second position P2 to the neutral position P0. The same applies to the case where the control unit 23 is configured to detect the elapse of the specified time and return from the second position P2 to the neutral position P0 after switching from the position P1 to the second position P2.

In the above-described embodiment, the throttle valve 16 is interposed between the first cylinder chamber a and the solenoid valve 15 so that the first cylinder chamber a
Although the discharge flow rate from the tank to the tank 17 is limited, the same effect can be expected even if the throttle valve 16 is provided in the inflow path of the working fluid to the second cylinder chamber b. Also in this case, the check valve 19 is connected in parallel with the throttle valve 16 in a direction that does not hinder the suction of the working fluid into the first cylinder chamber a. Throttle valve 16 in this case
The check valve 19 and the check valve 19 are shown in broken lines in FIG.

In the above embodiment, when the control section 23 detects that the weight value of the platform scale 7 is balanced except near the zero point,
Although it has been described that the solenoid valve 15 is automatically switched to the second position P2 after a stipulated time or immediately after the weight value is held, this is configured to be switched to the second position P2 by a switch operation of a staff member. You can also

When the measurement is completed and the object 9 to be weighed is removed from the platform 1, the weighing signal S falls below the specified weight, and the control unit 23 detects this state and sets the solenoid valve 15 to the first position. Two
It is also possible to switch to the position P2.

[0027]

As described above, according to the present invention, the compression spring is interposed between the support base on which the mounting base is mounted and the fixed side to lift the mounting base from the force applying portion of the load detecting device. ,
A first cylinder chamber in which a cylinder device is interposed in parallel with the compression spring between the support base and the fixed side and is compressed by a load from a mounting base of both cylinder chambers of the cylinder device, and the first cylinder chamber. Of the second cylinder chamber on the opposite side of the second cylinder chamber to the working fluid tank and the first switching state in which the first cylinder chamber is communicated to the tank, and the second cylinder is connected to the discharge port of the pump. Switching for switching the flow path of the working fluid between a second switching state in which the chamber is connected and a third switching state in which the second cylinder chamber is connected to the tank and the first cylinder chamber is connected to the discharge port of the pump. A direction in which a valve is provided and a throttle valve is provided in the discharge passage of the working fluid from the first cylinder chamber or the suction passage of the working fluid to the second cylinder chamber so as not to prevent the suction of the working fluid into the first cylinder chamber. Reverse connected in parallel to the throttle valve A valve is provided, the switching valve is set to the first switching state during standby, and when the detection state of the load detected by the load detecting device exceeds the specified weight, the switching valve is set to the second switching state, and then the switching valve is set to the second switching state. Since the control unit for switching the switching valve to the third switching state is provided, when the object to be measured is placed on the mounting table, the supporting table gently descends toward the load detection device at a unit time flow rate determined by the throttle valve. Thus, it is possible to avoid a situation in which the load detection device is loaded with the platform and the impact force acting on the platform acts on the load detection device.

Further, when the platform is loaded on the load detecting device and the control unit detects the measuring state, the switching valve is switched and the working fluid is pushed from the pump into the second cylinder chamber, and the stem of the cylinder device is pushed. Since the compression spring is further retracted to further compress the compression spring and lower the support table to a position where it does not contact the mounting table, it is possible to perform measurement while the device for cushioning is completely separated from the mounting table, and Since the total load acts on the load detection device, it is possible to realize more accurate measurement than before.

When the measurement is completed, the working fluid can be pumped into the first cylinder chamber to raise the support table to rapidly separate the mounting table from the load detecting device. It is effective when weighing is required.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a weighing device with a shock absorbing device of the present invention in a standby state.

FIG. 2 is an explanatory diagram of the progress of a state in which the control unit of the apparatus detects a measuring state.

FIG. 3 is an explanatory diagram of a measurement value reading state of the apparatus.

FIG. 4 is an explanatory diagram of an operation of returning to an initial state after the measurement value reading of the apparatus is completed.

FIG. 5 is a configuration diagram of a conventional weighing device with a shock absorbing device.

[Explanation of symbols]

 1 platform 7 scales [load detection device] 8 fixed side 9 object to be measured 10 support platform 11 compression spring 12 cylinder device a first cylinder chamber b second cylinder chamber 13 first pipe 14 second pipe 15 electromagnetic Valve [Switching valve] 16 Throttle valve 17 Tank 19 Check valve 23 Control unit 24 Pump P0 Neutral position [First switching state] P1 First position [Second switching state] P2 Second position [Third switching state] ]

Claims (1)

[Claims] 1. A compression spring is interposed between a support table on which the table is mounted and a fixed side to lift the table from the force applying portion of the load detecting device, and between the support table and the fixed side. A first cylinder chamber in which a cylinder device is interposed in parallel with the compression spring and is compressed by a load from a mounting table of both cylinder chambers of the cylinder device, and a first cylinder chamber on the opposite side of the first cylinder chamber. A first switching state in which both of the two cylinder chambers are in communication with a tank for working fluid, and a second switching state in which the first cylinder chamber is in communication with the tank and the second cylinder chamber is connected to the discharge port of the pump. And a switching valve for switching the flow path of the working fluid to a third switching state in which the second cylinder chamber is connected to the tank and the first cylinder chamber is connected to the discharge port of the pump, and the first cylinder chamber is provided. Discharge path of working fluid from the second cylinder A throttle valve is provided in the suction passage of the working fluid into the chamber, and a check valve connected in parallel to the throttle valve is provided in a direction that does not hinder the suction of the working fluid into the first cylinder chamber,
During standby, the switching valve is set to the first switching state, and when the measuring state in which the load detected by the load detection device exceeds the specified weight is detected, the switching valve is set to the second switching state, and then the switching valve is set to the first switching state. A weighing device with a shock absorbing device provided with a control unit for switching to the switching state of 3.