JPH0440409Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hydraulic cylinder suitable for use in controlling the angle of working machines such as rotaries and rice transplanters connected to tractors, traveling vehicles, and the like.

Conventionally, there has been no hydraulic cylinder whose length, ie, the position or amount of movement of the piston rod, can be accurately and easily detected. The object of the present invention is to provide a hydraulic cylinder in which the entire length of the cylinder can be accurately and easily determined regardless of the position of the piston rod.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof. FIG. 1 is a partially cutaway left side view of a tractor with a rotary connected to the rear as a working machine and equipped with an angle control device according to the present invention, and FIG. 2 is a plan view of the main parts thereof. In the figure, 1 is the tractor body, 2
is a rotary connected to a three-point link mechanism 3 at the rear thereof so as to be able to rise and fall freely, and is attached to the rear side of a hydraulic lift 10 attached to the upper surface of a transmission case 5 at the rear of the tractor main body 1 via a top link hinge 22.
One top link 2 in a three-point link mechanism 3
The front end of the top link 20 is connected and supported, the rear end of the top link 20 is connected to the upper central part of the front end of the rotary 2, and a pair of left and right lower links are connected to the lower corners of both sides of the transmission case 5 via lower link pins 23, 23. 2
The front ends of the lower links 21 and 21 are connected and supported, and the rear ends of each lower link 21 and 21 are connected and supported on both sides of the front end of the rotary 2.

The hydraulic lift 10 has a pair of left and right lift arms 1.
1 and 11 are interlocked, and the upper end of a connecting rod 24 is connected to the tip of the left lift arm 11, and the lower end thereof is connected to the middle of the left lower link 21.

A hydraulic cylinder 26 of the present invention is attached to the tip of the right lift arm 11 with its piston rod 26a extending downward, and the tip of the piston rod 26a is connected to the middle of the right lower link 21. Therefore, when the lift lever 7 on the side of the driver's seat 4 is operated rearward (or forward), the lift arms 11, 11 move up and down together, raising or lowering the rotary 2. Further, the tilt angle of the rotary 2 in the left-right direction is changed by driving the piston rod 26a of the hydraulic cylinder 26 back and forth. At the base end of the lift lever 7, there is a lift switch 51 that is turned on when the lever 7 is operated to raise the rotary 2.
(See Figure 4).

FIG. 3 is a partially cutaway rear view of the vicinity of the hydraulic cylinder 26, shown together with its control hydraulic circuit. The cylinder tube 26b is made of a non-magnetic material, and an annular magnet 26d is embedded in the middle in the moving direction of the piston 26c connecting the base end of the piston rod 26a. Each side end, i.e. piston 2
Magnetoresistive elements 26e and 26h are provided at portions facing each end of the stroke 6c, respectively.
Each magnetic resistance element 26e, 26h takes a resistance value proportional to the distance between each magnetic resistance element 26e, 26h and the magnet 26d attached to the piston 26c,
It is configured such that the resistance value is large when the magnets approach and becomes small when they are separated, and the resistance values of both magnetic resistance elements 26e and 26h are set to match when the piston 26c is located in the middle of its stroke. has been done.

A solenoid valve 65 is interposed between the hydraulic cylinder 26 and the hydraulic pump 66, and the solenoid 6
3 is energized, the solenoid valve 65 is in the position a, and the hydraulic pressure of the hydraulic pump 66 is transferred to the cylinder tube 26b.
When the solenoid 64 is energized, the solenoid valve 65 moves to position b. The hydraulic pressure from the hydraulic pump 66 is supplied to the piston rod advancing side oil chamber 26f, and the pressure oil in the piston rod retracting side oil chamber 26g is returned to the tank to advance the piston rod 26a. In the illustrated neutral position where both solenoids 63 and 64 are demagnetized, both oil chambers 26f and 26g in cylinder tube 26b are closed, piston rod 26a maintains the position at the time when solenoid valve 65 was switched, and the pressure from hydraulic pump 66 is The oil is returned to the tank. The pressure oil supplied from the hydraulic pump 66 is configured to be returned to the tank via the relief valve 67, and when the oil pressure in the hydraulic circuit becomes higher than the relief pressure of the relief valve 67, the relief valve 67 is opened. The pressure oil is then returned to the tank.

A cylindrical tilt angle sensor 40 is provided at the center of the upper surface of the rotary cover 16 of the rotary 2 .
The tilt angle sensor 40 has a light emitting element and a light receiving element fixed to face each other on the front and rear inner surfaces of the case, and a light shielding plate is hung in the gap between the facing light receiving element and the light shielding plate so as to be swingable in the left and right direction. A slit of a predetermined shape is formed at the height of the light-shielding plate facing the light-emitting and light-receiving elements, and the relative relationship between the light-shielding plate and the case, in other words, the left-right tilt angle of the work machine with the case attached relative to the vertical line. The right side of the rotary 2 is lower than the left side of the rotary 2, and as the tilt angle becomes larger, the output power of the tilt angle sensor 40 becomes larger.

FIG. 4 is an electronic circuit diagram for controlling the tilt angle of the rotary 2 in the left and right directions. In the figure, 31 is a battery whose negative pole is grounded to the body, and its positive pole is connected via a key switch 32 to a power terminal of a window comparator 30, which will be described later. The window comparator 30 is a semiconductor device that can discriminate a changing input voltage by comparing it with two freely settable comparison reference voltages, and in this embodiment, TCA965 manufactured by Siemens is used.

The power supply line of the battery 31 includes the above-mentioned tilt angle sensor 40 and resistors 4 connected to the respective magnetic resistance elements 26e and 26h provided in the hydraulic cylinder 26.
5, 46, and further the excitation coil 5 of the electromagnetic relay 52
2C is connected, and the excitation coil 52C is
The body is grounded via a lift switch 51 that is provided at the base end of the lift lever 7 and is turned on when the rotary 2 is operated to raise it.

The tilt angle sensor 40 is a normally closed contact 5 of an electromagnetic relay 52.
an input terminal to which a signal to be subjected to comparison identification of the window comparator 30 is applied via 2b;
is giving to

The potential at the connection point between the resistor 45 and the magnetoresistive element 26e is applied to the differential amplifier 3 via the buffer amplifier 37a.
8 and a comparator 39a to be described later.
The potential at the connection point between the resistor 46 and the magnetoresistive element 26h is applied to the other end of the differential amplifier 38 via the buffer amplifier 37b, and the + input terminal of the comparator 39b, which will be described later. given to the terminal. The output of the differential amplifier 38 is applied to the input terminal of the window comparator 30 via a normally open contact 52a of an electromagnetic relay 52.

As shown in FIG. 5, the terminal of the window comparator 30 is an input terminal to which a voltage defining the midpoint of the window is applied, and is connected to a variable resistor 33 interposed between the power supply line of the battery 31 and the body ground. Potential at the connection point of the series circuit with the resistor 34
V ₈ is given, and the resistance value of the variable resistor 33 is determined by the knob 7 arranged on the operation column 72 in front of the driver's seat 4.
It can be changed in 1.

The input voltage to the terminal of the window comparator 30 defines the 1/2 width of the window as shown in FIG.
The potential V ₉ at the connection point of the series circuit with 6 is given.

The terminals of the window comparator 30 are output terminals, and are connected to drive circuits 61 and 62 each formed by connecting two transistors, and when the respective outputs V ₂ and V14 become low level, the hydraulic pressure is A high level signal is given to each solenoid 63, 64 that controls the supply of pressure oil to the cylinder 26 via the normally closed contacts 53b, 54b of the electromagnetic relays 53, 54, respectively, to excite the solenoids 63, 64. Ori,
As described above, the piston rod 26a of the hydraulic cylinder 26 advances (or retracts) by energizing the solenoid 63 or 64.

On the other hand, the potential at the connection point between the resistor 45 and the magnetoresistive element 26e is applied to the + input terminal of the comparator 39a via the buffer amplifier 37a, and the potential at the connection point between the resistor 46 and the magnetoresistive element 26h is applied to the buffer amplifier 37a. It is applied to the + input terminal of comparator 39b via 37b. Each comparator 39a, 39
The - input terminal of b is given the potential at the connection point of a series circuit of resistors 41 and 42 interposed between the power supply line of the battery 31 and the body ground. This potential is applied to the piston 26 of the hydraulic cylinder 26.
When c reaches the retracting or advancing limit position of the piston rod, each resistor 45, 46 and each magnetic resistance element 2
The connection points with 6e and 26h are set to be slightly lower than the output potential, and the positive input potential of each comparator 39a and 39b is higher than this potential (that is, the position of the piston 26c of the hydraulic cylinder 26 is set to When the retracting or advancing limit position is reached), each comparator 39a, 39b applies a high level signal to the switch transistor 43, 44, respectively, to turn it on, and the excitation coil 53C, of each electromagnetic relay 53, 54,
54C are respectively excited. and each excitation coil 53
Normally closed contacts 53b and 54b are activated by excitation of C and 54C.
is opened, and the solenoid 6 in the solenoid valve 65
3 and 64 are respectively demagnetized.

Next, based on FIG. 5, the window comparator 30
The operation will be briefly explained. Figure 5 A and B show the output terminals of the window comparator 30, and the outputs V ₂ and V14 of the window comparator 30 are plotted on the horizontal axis.
The figure shows the input V ₆ to the input terminal 0. V14 is low level when V ₆ < V ₈ − V ₉ ,
It becomes high level when V ₆ > V ₈ −V ₉ , and V ₂ becomes high level when V ₆ <
High level when V ₈ + V ₉ , low level when V ₆ > V ₈ + V ₉ . The range from V ₈ −V ₉ to _{V 8} +V ₉ is called a window, with V ₈ defining the midpoint of the window and V ₉ defining 1/2 of its width. _V8 , which defines the midpoint of the window, is appropriately set by the resistance value of the variable resistor 33. The input V ₆ to the input terminal is the lift arm switch 5 that detects the upper limit of the lift arm 11.
1 is off, the output of the tilt angle sensor 40 is input, and depending on the tilt state of the rotary 2 with respect to the horizontal plane, V ₂ or V14 becomes low level, and the solenoid 63 or 64 is energized, so that the hydraulic cylinder 26 is activated. The rotary 2 is controlled by the variable resistor 3
The horizontal tilt angle is controlled so that the V ₆
If it is within the window, it is assumed that the rotary 2 is in a substantially horizontal state and no control is performed. Further, when the lift switch 51 is on, the output of the operational amplifier 38 is input to the window comparator 30, and the resistors 45 and 46 and the magnetoresistive elements 26e and 2
6h, _V2 or V14 becomes low level depending on the potential at each connection point, and the solenoid 63 or 64 is energized. As a result, the piston rod 26a of the hydraulic cylinder 26 is controlled to an appropriate state determined by the variable resistor 33. Rotary 2 for main body 1
If the piston 26 is not tilted,
The rotary 2 is controlled to be located in the middle of the stroke of c, and the rotary 2 is not tilted in either the left or right direction with respect to the tractor main body 1.

In the tractor configured as described above, during work, the rotary 2 is controlled to an appropriate state determined by the variable resistor 33, and in this embodiment, it is set to be horizontal, so that the rotary 2 is always kept horizontal. controlled by. That is, the key switch 32
When the rotary 2 is turned on to move the rotary 2 to the lower working position, the lift switch 51 is turned off and the tilt angle sensor 40 is turned on.
outputs a potential corresponding to the horizontal tilt angle of the rotary 2 with respect to the horizontal plane, and the window comparator 30 outputs the potential in order to keep the rotary 2 in a horizontal state.
Set _V2 or V14 to low level, solenoid 63
Or, by energizing the piston rod 26a of the hydraulic cylinder 26, the piston rod 26a of the hydraulic cylinder 26 is moved in or out, and the right side of the rotary is raised or lowered to make the rotary 2 horizontal.

When the machine reaches the headland after completing one stroke of plowing work and turns the machine around, when the lift lever 7 is operated to raise the rotary 2, the lift switch 51 is turned on and the rotary 2 rises, but the lift When the excitation coil 52C of the electromagnetic relay 52 is excited by turning on the switch 51, the normally closed contact 52C of the electromagnetic relay 52 is excited.
b is open and the normally open contact 52a is closed, so that the output of the tilt angle sensor 40 is not input to the window comparator 30, but the output of the differential amplifier 38 is input to the window comparator 30. The window comparator 30 then operates the hydraulic cylinder 26 based on the output of the differential amplifier 38.
is controlled to a state determined by the variable resistor 33, and in this embodiment, the piston 26c of the hydraulic cylinder 26
In other words, the full length of the hydraulic cylinder 26 and the full length of the left connecting rod 24 match so that the rotary 2 is tilted in either the left or right direction with respect to the tractor body 1. control so that there is no state. That is, when the position of the piston 26c of the hydraulic cylinder 26 is on the rod retraction side (or advancement side) from the center of its stroke, the resistance 45 or 46 and the magnetic resistance element 26e
Or, the potential at the connection point with 26h becomes higher than the potential at the other connection point, the output V ₂ (or V16) of the window comparator 30 becomes a low level, the solenoid 63 or 64 is excited, and the hydraulic cylinder 26
The piston rod 26a advances (or retracts). And the piston 26c is the cylinder tube 2
6b, the output of the operational amplifier 38 is within the window, the solenoid 63 or 64 is demagnetized, and the rotary 2 is not tilted in either the left or right direction with respect to the tractor body 1.

Since the rotary 2 is controlled to a state set by the resistance value of the variable resistor 33, it can be controlled to be tilted at a predetermined angle from the horizontal plane based on the detection result of the tilt angle sensor 40, and further, Since the expansion and contraction state of the piston rod 26a can also be continuously detected, it is also possible to control the rotary 2 to a predetermined tilt angle with respect to the tractor main body 1 based on the output of the differential amplifier 38.

Also, during the horizontal control described above or in horizontal control by manual operation, the hydraulic cylinder 2
When the piston 26c of No. 6 reaches the vicinity of the retraction or advancement limit position of the rod 26a, the potential at the connection point between the resistor 45 or 46 and the magnetic resistance element 26e or 26h increases, and the + input potential of the comparator 39a or 39b becomes -. The output potential of the comparator 39a or 39b becomes higher than the input potential, and the output of the comparator 39a or 39b becomes high level, and the electromagnetic relay 5
As a result, the No. 3 or 54 excitation coil 53C or 54C is energized and its normally closed contact 53b or 54b is opened, so that the solenoid 63 or 64 is deenergized and the solenoid valve 65 returns to the neutral position. Therefore, since there is no risk of the pressure in the hydraulic circuit increasing, the relief valve 67 does not operate, and the generation of abnormal noise when the relief valve 67 operates can be prevented.

As detailed above, the hydraulic cylinder according to the present invention includes a piston that has a magnet in a part of its moving direction, a cylinder tube made of a non-magnetic material, and a cylinder tube that is provided outside the cylinder tube and has a distance to the magnet. Since the piston rod is equipped with a magnetic detector that outputs a signal corresponding to the piston rod, its entire length, that is, the position or amount of movement of the piston rod can be accurately and easily detected. When used in an angle control device as in the embodiment, the present invention has excellent features such as being able to detect the tilting angle of the working machine with respect to the machine with a simple structure, and using this detection result for various controls. be effective.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention.
The figure is a partially cutaway left side view of a tractor equipped with a hydraulic cylinder according to the present invention, Fig. 2 is a plan view of the main part thereof, and Fig. 3 is a partially cutaway rear view of the hydraulic cylinder of the present invention shown together with a control hydraulic circuit. , FIG. 4 is a control electronic circuit diagram thereof, and FIG. 5 is an explanatory diagram of the operation of the window comparator. 1...Tractor body, 2...Rotary, 11...
...Lift arm, 20...Top link, 22...
...Lower link, 24...Connection rod, 26...Hydraulic cylinder, 26a...Piston rod, 26...
...Cylinder tube, 26c...Piston, 26
d... Magnet, 26e, 26h... Magnetoresistive element,
30... Window comparator, 40... Tilt angle sensor, 65... Solenoid valve, 63, 64... Solenoid.

Claims (1)

[Scope of utility model registration request] It includes a piston that has a magnet in a part of its moving direction, a cylinder tube made of a non-magnetic material, and a magnetic detector that is provided outside the cylinder tube and outputs a signal corresponding to the distance to the magnet. A hydraulic cylinder characterized by: