JPS6217298Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a hydraulic drive device used as a driving means for self-propelled agricultural machines such as tractors and combines, and civil engineering machines. This type of hydraulic drive device conventionally combines a variable displacement hydraulic pump and a constant displacement hydraulic motor, and adjusts the amount of pressure oil supplied from the hydraulic pump to adjust the output of the hydraulic motor. However, variable displacement hydraulic pumps have drawbacks such as being complex and expensive, having poor transmission efficiency, and even when neutral is selected, there is a risk of slight movement. The present invention has been devised in view of the above circumstances, and its purpose is to provide two constant displacement hydraulic motors connected in series with a dual-pressure oil supply/discharge port that has both pressure The oil supply and discharge ports are connected to the oil discharge port and the oil suction port of the hydraulic pump through one electromagnetic on-off valve that also serves as the oil supply and discharge port, and the other pressure oil supply and discharge ports of each hydraulic motor are connected to each other. The control unit is connected to an oil discharge port and an oil suction port of a hydraulic pump through a single electromagnetic on-off valve, and is provided with a control unit that provides an open/close control signal with a variable duty ratio to each of the electromagnetic on-off valves. By doing so, individual drive control for each hydraulic motor is possible, and when used in a vehicle such as a combine harvester, it can be used not only for steering, forward, reverse, and speed control, but also for spin turn, forced steering, and braking control. To provide a hydraulic drive device which can perform steplessly and freely using a constant displacement hydraulic pump and a hydraulic motor, and which has a small number of parts and can greatly simplify the configuration. . Hereinafter, the present invention will be specifically explained based on drawings showing embodiments thereof. FIG. 1 is a perspective view of a combine to which a hydraulic drive device according to the present invention (hereinafter referred to as the device of the present invention) is applied, and FIG. 2 is a hydraulic circuit diagram of the device of the present invention. indicates the threshing section, and the combine runs on the left and right crawlers (only one side is shown in the drawing) and moves to the reaping section 2.
The grain culms are harvested, the harvested grain culms are sent to a threshing section 3 via a conveyance mechanism, and after being threshed in the threshing section 3, the straw is bundled and discharged to the rear.
The drive wheels of the left and right crawlers 1 are driven by hydraulic motors Ml and Mr as shown in FIG. In FIG. 2, P indicates a constant displacement hydraulic pump, and Ml and Mr also indicate constant displacement hydraulic motors. Hydraulic motors Ml and Mr are connected in series with their respective pressure oil supply ports for forward rotation drive (pressure oil supply and discharge ports for reverse rotation drive, hereinafter simply referred to as pressure oil supply and discharge ports) connected to each other. Connected pressure oil supply and discharge ports and each hydraulic motor Ml, Mr
The pressure oil supply and discharge ports for forward rotation drive (pressure oil supply and discharge ports for reverse rotation drive, hereinafter simply referred to as pressure oil supply and discharge ports) are respectively electromagnetic on-off valves V ₁ to V ₆ that can be switched at high speed. It is connected in parallel to the oil discharge port side and the oil suction port side of the hydraulic pump P via. These electromagnetic on-off valves V ₁ to _{V 6} have an open position that allows pressure oil to flow,
Its solenoid in two positions with a closed position that prohibits flow.
It can be switched by excitation and demagnetization of Vs ₁ to Vs ₆ , and is hereinafter referred to as a switching valve. That is, hydraulic motor Ml
One pressure oil supply/discharge port of the hydraulic motor Ml is connected to the oil discharge port side of the hydraulic pump P via a switching valve _V1 , and to the oil suction port side of the hydraulic pump P via a switching valve _V2 . The other pressure oil supply/discharge port and the pressure oil supply/discharge port of the hydraulic motor Mr connected thereto are connected to the oil discharge port side of the hydraulic pump P via a switching valve _V3 which is also used for both pressure oil supply/discharge ports. _The other pressure oil supply/discharge port of the hydraulic motor Mr is connected to the oil discharge port side of the hydraulic pump P via the switching valve _V5 . In addition, the switching valve V ₆
The pressure oil supplied from the hydraulic pump P is connected to the oil suction side of the hydraulic pump P via the switching valve V ₁ ,
V ₃ , V ₅ or one or two of them are supplied to the hydraulic motors Ml, Mr, and after passing through the hydraulic motors Ml, Mr, or directly without passing through the hydraulic motors Ml, Mr, the switching valves V ₂ , V ₄ , V ₆ or one or two of them
A hydraulic closed circuit is formed in which the oil is returned to the hydraulic pump P through the pump. The high-speed switching valves V ₁ to V ₆ are 2-port, 2-position switching type solenoid valves that can be switched repeatedly at high speed (with intervals of several milliseconds), and the solenoids Vs ₁ to _{Vs 6} When solenoid Vs 1 to Vs 6 are energized, the first position is selected to cut off the pressure oil as shown in the figure, and when the solenoids Vs ₁ to _{Vs 6} are energized, the second position is selected to allow the pressure oil to flow. It is set as.
CN is a control unit for each of the switching valves V ₁ to _{V 6} , and is composed of a pulse generation circuit etc. that allows the duty ratio of the generated pulse signal to be varied in the range of 0 to ₁ . A pulse signal with a level sufficient to drive solenoid Vs ₆ can be output individually to each solenoid Vs ₁ to Vs ₆ at a predetermined duty ratio.

【table】

[Table] When moving the combine harvester forward, select one of the switching valves V ₁ to V ₆ as shown in the first column of Table 1.
V ₁ , V ₄ , V ₅ are all solenoid Vs ₁ ,
While Vs ₄ and Vs ₅ are demagnetized to select the first position, the switching valves V ₂ , V ₃ , and V ₆ have their solenoids Vs ₂ , Vs ₃ , and Vs ₆ energized to select the second position. Allows you to select a location. As a result, the pressure oil from the hydraulic pump P passes through the switching valve _V3 to each hydraulic motor Ml, Mr.
are passed through in the direction of forward rotation, respectively, and the switching valves V ₂ ,
The water is returned to the hydraulic pump P via _V6 , and the hydraulic motors Ml and Mr are rotated in the normal direction, the crawler is driven via the left and right drive wheels, and the combine moves forward. Forward speed adjustment is performed using switching valves V ₂ , V ₃ , and V ₆
The duty ratio of each pulse signal to be applied from the control unit CN to the solenoid can be increased or decreased in synchronization with the increase or decrease of the forward speed. Of course, the duty ratio of the pulse signal may be changed greatly or small only for the solenoid of the switching valve _V3 . To correct the direction of movement of the combine, use the solenoid Vs 2 of the switching valve V ₃ while keeping the duty ratio of the pulse signal constant for the solenoid Vs ₃ of the switching valve V 3. To change the direction of movement to the left, use the solenoid Vs ₂ of the switching valve V ₂ .
The duty ratio of the pulse signal to the solenoid Vs ₆ of the switching valve V ₆ may be decreased, or the duty ratio of the pulse signal to the solenoid Vs ₆ of the switching valve V 6 may be increased. It is only necessary to increase the value of Vs 6 or to decrease the duty ratio of the pulse signal to the solenoid Vs ₆ . When implementing so-called forced steering in which the left and right crawlers of the combine are driven regardless of the load applied to them, for example, as shown in column 8, the switching valve
V ₁ , V ₄ , V ₅ are all solenoid Vs ₁ ,
While Vs ₄ and Vs ₅ are demagnetized to select the first position, the switching valve V ₃ is connected to its solenoid.
Energize Vs ₃ to select the second position, and in this state, change the duty ratio of the pulse signal for the solenoids Vs ₂ and Vs ₆ of the switching valves V ₂ and V ₆ to a large or small value according to the drive output ratio. Bye. Figure 3 A and B show the switching valves V ₂ , V ₆ solenoid Vs ₂ ,
Excitation timing chart for Vs ₆ ,
For the solenoid Vs ₂ , the period t ₀ as shown in Fig. 3 A,
The time t ₂ at the high level, that is, the duty ratio t ₂ /
The pulse signal of t ₀ is also applied to the solenoid Vs ₆ for a period t ₀ and a high level time t ₆ as shown in Fig. 3 (b).
(However, t ₆ = 2t ₂ ), that is, assuming that a pulse signal with a duty ratio of 2t ₂ /t ₀ is output, the ratio of the amount of pressure oil passing through the switching valves V ₂ and V ₆ is considered to correspond to the above duty ratio. Therefore, the pressure oil is diverted to the hydraulic motors Ml and Mr at a ratio of 1:2, and the output of each hydraulic motor Ml and Mr is also set according to this amount of pressure oil, and at this output. The left and right crawlers will be driven. In the above case, the solenoids Vs ₂ and Vs ₆ of the switching valves V ₂ and V ₆
If the duty ratio of the pulse signal for one of the two crawlers is set to zero, it is possible to perform so-called deflock control in which one of the left and right crawlers is stopped and the other crawler is driven with an arbitrary output. When moving the combine in reverse, the switching valves V ₂ , V ₃ , and V ₆ are connected to their respective solenoids as shown in the second column of Table 1.
While Vs ₂ , Vs ₃ , and Vs ₆ are demagnetized to keep the first position selected, the switching valves V ₁ , V ₄ , and V ₅ have their solenoids Vs ₁ , Vs ₄ , and Vs ₅ energized. Allow the second position to be selected. As a result, the pressure oil from the hydraulic pump P flows through the respective hydraulic motors Ml and Mr through the switching valves V ₁ and V ₅ in the reverse direction, respectively.
The flow is returned to the hydraulic pump P via the switching valve _V4 , and each hydraulic motor Ml, Mr is reversed, and the left,
The crawler is reversely driven via the right drive wheel, and the combine moves backward. Increase/decrease in reverse speed and corrective control in reverse direction are the same as in the case of forward described above, and forced steering when reversing (see column 9 of Table 1).
The defrock control is also substantially the same as in the case of forward movement described above. When the combine harvester is in a so-called free state where it can be towed, each switching valve V ₁ is set as shown in the third column of Table 1.
~ _V6 energizes each of the solenoids _Vs1 to _Vs6 to select the first position, and the pressure oil from the hydraulic pump P passes through the switching valves _V1 , _V3 , and _V5 , and is transferred to the hydraulic motors Ml, Mr.
The switching valves V ₂ , V ₄ ,
The water is returned to the hydraulic pump P via _V6 , and each of the hydraulic motors Ml and Mr becomes freely rotatable. Of course, the driving of the hydraulic pump P may be stopped. When braking a running combine harvester, as shown in the fourth column of Table 1, the switching valves V ₁ , V ₂ ,
V ₅ , V ₆ are the respective solenoids Vs ₁ , Vs ₂ , Vs ₅ , Vs ₆
is demagnetized to select the first position,
When the switching valves V ₃ and V ₄ select the second position by energizing their respective solenoids Vs ₃ and Vs ₄ , the hydraulic pump P
Pressure oil from the hydraulic motor Ml, Mr through the switching valve V ₃
The oil is returned to the hydraulic pump P via the switching valve _V4 without flowing through it, and one of the pressure oil supply and discharge ports in each of the hydraulic motors Ml and Mr is in a sealed state. Each hydraulic motor
Ml and Mr remain immobile. In this case, as shown in the fifth column of Table 1, contrary to the above, the switching valves V ₃ and V ₄ have their solenoids Vs ₃ and Vs ₄ demagnetized to select the first position, switching valve
V ₁ , V ₂ , V ₅ , V ₆ are the solenoids Vs ₁ , Vs ₂ ,
Braking can be similarly performed by exciting Vs ₅ and Vs ₆ to select the first position. When spin-turning the combine to the left (or right), selector valves V ₂ , V ₃ , V ₄ , V ₅ (or V ₁ , V ₃ , V ₄ , V 6 ) are used as shown in columns 6 and ₇ of Table 1. ) demagnetizes each solenoid to select the first position, and the switching valves V ₁ , V ₆ (or V ₂ , V ₅ ) deenergize their solenoids Vs ₁ , Vs ₆ (or Vs ₂ , Vs ₅ ). If the second position is selected by energizing the hydraulic pump P, the pressure oil from the hydraulic pump P passes through the switching valve V ₁ (or V ₅ ) in the direction of reversing the hydraulic motor Ml (or Mr), and vice versa. Flow flows through Mr (or Ml) in the direction of forward rotation, reverses the left drive wheel (or right drive wheel) which is returned to the hydraulic pump P via the switching valve V ₆ (or V ₂ ), and reverses the right drive wheel (or right drive wheel). Or the left drive wheel) is rotated in the normal direction, causing the combine to spin and turn. As described above, the proposed device has a hydraulic circuit that combines two constant displacement hydraulic motors and six switching valves, that is, electromagnetic switching valves, and furthermore, each of the electromagnetic switching valves has a separate hydraulic circuit. A control unit is provided that provides an opening/closing control signal with a variable duty ratio to control the opening/closing of the electromagnetic opening/closing valve.
To realize a hydraulic drive device that can freely perform spin turns, forced steering, defrock control, and speed adjustment without using a variable displacement hydraulic pump, and has a significantly simplified configuration with fewer parts. be able to.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a combine to which the proposed device is applied, Figure 2 is a hydraulic circuit diagram of the proposed device, and Figure 3 is a solenoid used to forcefully steer the combine.
This is an excitation timing chart for Vs ₂ and Vs ₆ . P...Hydraulic pump, Ml, Mr...Hydraulic motor,
V ₁ , V ₂ , V ₃ , V ₄ , V ₅ , V ₆ ... switching valve, CP ... charge pump.

Claims (1)

[Scope of utility model registration request] The mutually connected double-pressure oil supply/discharge ports of two fixed-displacement type hydraulic motors connected in series are connected to the hydraulic pump via one electromagnetic on-off valve, which is also used for both the double-pressure oil supply/discharge ports. The other pressure oil supply/discharge ports of each hydraulic motor are connected to the oil discharge port and oil suction port of the hydraulic pump through one electromagnetic on-off valve, respectively. A hydraulic drive device, characterized in that it is provided with a control section which is connected to each other and provides a separate duty ratio variable opening/closing control signal to each of the electromagnetic opening/closing valves.