JPH02485Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a pressure oil flow rate correction circuit. Figure 1 shows one of the pressure hydraulic circuits of a conventional power shovel.
This is an example. The running performance in this case is that the discharge flow rate of each of the two pumps 1, 1 is sent to the respective running hydraulic motors 2, 2 to rotate, that is, drive, so the hydraulic pump → control The manufacturing error between the valve and the hydraulic motor is within the allowable range, and there is little bending when running. Another conventional pressure oil flow rate correction circuit is the same as the circuit shown in FIG. 2 showing the embodiment of the present invention, except that the flow rate correction valve 3 is removed. In this case, since a diverting error is added, the performance of the diverting valve exceeds the permissible value, causing the vehicle to swerve. In the case of the conventional two-pump system in which the flow rate correction valve 3 is removed from FIG. 2, the first pump 4 and the second pump 5 rotate hydraulic motors 9 and 10 by control valves 7 and 8, respectively. It showed good driving performance. However, when the load is light, the drive source 11
It was uneconomical because there was a surplus of power. Therefore, a method has been adopted in which a third pump 6 is installed to increase the operating speed when the load is light (for example, when driving). In this case, when the load increases, the discharge pressure of the hydraulic pump increases, and the three pumps 4,
If all pumps 5 and 6 are in operation, the drive source 11 will run out of power, so at that time the discharge pressure of the third pump 6 is reduced to zero using the unload valve 12. The unload valve 12 has a first pump 4 and a second pump.
The discharge pressures of the discharge lines 13 and 14 of the pump 5 act as unload pilot pressure. Now, the reason why the traveling curve mentioned in the conventional explanation occurs is that the rotational speed of the hydraulic motor is different on both sides, and when the situation is actually measured, it is found that the pressure (i.e., the flow rate) on the winning side (the side with higher rotational speed) ) is high. In other words, a crawler (track type) like a power shovel.
It is known that in a running vehicle, the pressure and flow rate on the leading side are greater than on the following side, causing a phenomenon in which the trailing side is dragged. The present invention was proposed in order to eliminate the above-mentioned drawbacks of the conventional system, and includes a system including a hydraulic motor to which pressure oil is supplied from a first pump, and a system which is supplied with pressure oil from a second pump. In a hydraulic circuit configured to supply pressure oil from a third pump to a system equipped with a hydraulic motor via a flow divider valve and a flow rate correction valve, the pressure oil from the third pump is One part is divided through a flow rate correction valve to supply each of the two systems, and the higher pressure of the pressure oil supplied to the hydraulic motors of the two systems is selected to correct the flow rate. A shuttle valve is provided that acts on both sides of the spool of the valve and moves the spool according to the pressure difference of the pressure oil, and the flow rate correction valve is supplied to the hydraulic motor from the flow rate correction valve to the system where the pressure of the pressure oil is lower than that of the other side. It has a configuration that can supply a certain amount of pressure oil and correct the amount of travel bending, and in a two-train travel system, the pressure in the train with a higher traveling speed is higher than the pressure in the train with a lower speed. With this in mind, we aim to provide a pressure oil flow correction circuit that replenishes the flow divided by the pressure difference to a slightly slower system. An embodiment of the present invention will be explained below with reference to the drawings. Fig. 2 shows an embodiment of the pressure oil flow rate correction circuit of the present invention, and the reference numerals of each part shown in the section of the conventional explanation above refer to the structure and operation. Since they are the same, we will use them as they are in the explanation. Now, FIG. 2 shows a system equipped with a hydraulic motor 9 to which pressure oil is supplied from the first pump 4, and a system equipped with a hydraulic motor 10 to which pressure oil is supplied from the second pump 5, respectively. Third
This is a device that supplies pressure oil from the pump 6 through a diversion valve 15. A part of the pressure oil from the third pump 6 is sent to the flow rate correction valve 3 through the discharge line 16, and The discharge lines 13 and 14 of the two systems are supplied via check valves 17 and 18, respectively.
Note that 11 is a driving source, and 12 is an unload valve. Furthermore, the pressure of the pressure oil supplied to the hydraulic motors 9 and 10 of the two systems is applied to both sides of the spool 19 of the flow rate correction valve 3 shown in FIG. By moving the valve 3, the system with the lower pressure of the pressure oil supplied from the flow rate correction valve 3 to the hydraulic motors 9, 10 is supplied with a larger amount of pressure oil than the other system. The structure and operation of the embodiments shown in FIGS. 2 and 3 will be explained in detail below. Note that the structure and operation of each part shown in the conventional explanation in FIG. 2 are the same in the present invention, so a detailed explanation of this part will be omitted. The excavation operation of a power shovel does not always require continuous simultaneous operation, but is performed in combination with individual and simultaneous operations, and the load fluctuates widely, and the moment when digging force is required and the working speed are required. There are moments when you feel that way. Only when this working speed is required, the first, second, and
The discharge amounts of two or more of the third pumps 4, 5, and 6 are combined to double the speed. Next, the control valves 7 and 8 (also referred to as distributors) will be explained in detail.
The embodiment shown in FIG. 2 shows a manual type, and when the control levers 20 and 21 are operated in the operating direction (forward, stop, reverse), the control valve 7 switches the pressure oil in the discharge line 13 to the output line 22 or 23. Normally in normal open (stop position),
The control lever 20 is in neutral, and the discharge line 13 does not communicate with the output line 22 or 23, but communicates with the return line. The control valve 8 also has the same effect. Next, we will explain the flow dividing valve 15 (also called a merging valve because it adds the flow rate to the discharge volume of the first pump 4 and the second pump 5).This valve has the function of dividing the discharge volume of the hydraulic pump into two equal parts. It is usually a spool valve type. As shown in Fig. 5, the incoming flow rate at P' ₀ is divided into P' ₁ and P' ₂ , but in a simple flow dividing mechanism, the pressure at P' ₁ and P' ₂ is Q∞(P' ₀ −P′ ₁ ) or (P′ ₀ −P′ ₂ ), so the flow rate is not divided equally. Therefore, a variable throttle is created using a spool valve, and the opening degree of the spool port is adjusted so that the flow rate is divided into two even if P' ₁ or P' ₂ is different. Next, the flow rate correction valve 3, which is a feature of the present invention, will be explained. This flow rate correction valve 3 is constructed as shown in FIG. 3, and the spool 19 is inserted into the hole of the valve body 24. Same spool 19
are pressed from both sides by compression springs 26, 26 whose pressing force is adjusted by adjustment screws 25, 25, and the large diameter portions 27, 27 on both sides and the central large diameter portion 2
8 is formed. Also, 29 is a flow port, a
is an inlet port connected to the discharge line 16 of the third pump 6 in FIG. 2; b is an outlet port connected to the discharge line 13; c is an outlet port connected to the discharge line 14; The connected pilot port e is a pilot port connected to the pilot line 31. Now, the inflow amount from the inlet port a is distributed to the outlet ports b and c, and the amount of distribution depends on the magnitude of the pilot pressure at the pilot ports d and e.
That is, the characteristics of the flow rate correction valve 3 are as shown in the characteristic diagram of FIG. In Fig. 4, if P ₁ is the pressure generated in the first pump 4 → motor line, P ₂ is the pressure generated in the second pump 5 → motor line, then P ₁ > P ₂ or P ₂ ＞Flow rate Q by P ₁
shows that the changes. Straight lines B and C are compression springs 2
The characteristic determined by the spring constant of 6, the difference between straight lines A and B, ie, _Q1 , is determined by the amount of polymerization (wrap amount) of the flow port 29. That is, _Q1 is caused by underlap. In addition, 32 and 33 in FIG. 2 are brake valves, 34 and 35 are shuttle valves (valves that select and transmit the higher pressure), and 3
6 and 37 are from the control valve 8 to the brake valve 33
38, 39, 40, 41 are supply and return lines from the brake valves 32, 33 to the hydraulic motors 9, 10, 42 is a coupling, 43 is an oil tank, 44 is a filter, and 45 is a suction line. . Hereinafter, the present invention will be further explained in detail with reference to the following specific examples. Example The relationship between the reference (design) flow rate generated in the two systems shown in the pressure oil flow rate correction circuit in FIG. %} When the control valves 7 and 8 are fully open, {the rotation speed of the hydraulic motor 9 is 100% and the rotation speed of the hydraulic motor 10 is 100%}. At this time, the travel bending amount is 0%. Next, equip the third pump 6 (discharge rate 100%),
If the diverter valve 15 functions correctly, the above values will be 100+50=150% for each of the hydraulic motors 9 and 10, and 50%
You can get the best performance. However, each device has performance differences due to manufacturing tolerances, and the values are shown in Table 1 as an example.

[Table] In other words, an error of 6% in the total width will occur. Therefore, the output line (load line) 22 or 23 and 3
The shuttle valves 34, 35 select the higher pressure of either 6 or 37 and act on the pilot ports d, e of the flow rate correction valve 3 as the pilot pressure, so that Q as shown in FIG. By replenishing the discharge line 13 of the system of the pump 4, the required flow rate of this system is sufficient, the pressure is balanced, and the amount of travel bending can be corrected. As explained in detail above, the present invention is equipped with a three-pump system, and the pressure oil from the third pump is transferred to the first,
In a system in which pressure oil from the second pump is supplied to each system equipped with each hydraulic motor via a diversion valve, performance differences between each device (physically, it is impossible to Therefore, by providing the flow rate correction valve of the present invention and correcting the flow rate, the performance can be kept within the guaranteed performance standard value. Therefore, performance can be obtained without increasing costs, and conventionally, running curves were detected only through actual vehicle tests, and it was necessary to reload each device at that point, but with this invention, by installing a flow rate correction valve, Since performance can be obtained only by adjusting these parameters, operation is simple and economical. Also, according to this invention,
A shuttle valve is provided that selects the higher pressure of the pressure oil supplied to the hydraulic motor and applies it to both sides of the spool of the flow rate correction valve, and moves the spool according to the pressure difference of the pressure oil. The amount of bending can be corrected. In other words, it is possible to improve straight running performance. Note that the present invention is effective when applied to a power shovel or the like having a two-line motor system.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram showing an example of a conventional power shovel, Fig. 2 is a pressure oil flow correction circuit diagram showing an embodiment of the present invention, and Fig. 3 is a detailed cross section of the flow correction valve in Fig. 2. Figure 4 is a characteristic diagram of the compensation valve,
FIG. 5 is a functional explanatory diagram of the diverter valve in FIG. 3. Explanation of the main parts of the diagram, 3...Flow rate correction valve, 4...
...First pump, 5...Second pump, 6...Third pump, 7,8...Control valve, 9,10...
Hydraulic motor, 15... Diversion valve, 19... Spool of flow rate correction valve, 34, 35... Shuttle valve.

Claims (1)

[Scope of utility model registration request] A system equipped with a hydraulic motor to which pressure oil from the first pump is supplied, and a system equipped with a hydraulic motor to which pressure oil from the second pump is supplied, are each supplied with pressure from a third pump. In a hydraulic circuit in which oil is supplied via a flow rate correction valve and a flow rate correction valve, a portion of the pressure oil from the third pump is diverted via the flow rate correction valve to each of the two systems. At the same time, the higher pressure of the pressure oil supplied to the hydraulic motors of the two systems is selected and applied to both sides of the spool of the flow rate correction valve, and the pressure oil is equalized according to the pressure difference of the pressure oil. A shuttle valve for moving the spool is provided, and a system with a low pressure of pressure oil supplied from the flow rate correction valve to the hydraulic motor is supplied with a larger amount of pressure oil than the other, thereby making it possible to correct the amount of travel bending. A pressure oil flow rate correction circuit featuring: