WO2016093393A1 - Hydraulic circuit of construction equipment - Google Patents

Abstract

Disclosed is a hydraulic circuit of construction equipment, comprising: a variable displacement main pump and a fixed displacement auxiliary pump that are driven by an engine; a hydraulic actuator that receives hydraulic oil from the main pump; a main control valve installed between the main pump and the hydraulic actuator to control the operation of the hydraulic actuator; an oil pressure sensor installed in a supply passage of the main pump to detect the pressure of the main pump; a joint passage that extends from the supply passage of the auxiliary pump and is connected to the downstream side of the oil pressure sensor on the supply passage of the main pump; an electric proportional valve that is installed on the joint passage and regulates the ratio of valve opening according to an applied current value to control the confluence flow rate; and a variable relief valve that is installed on the drain passage of the auxiliary pump and controls the pressure of the auxiliary pump to make the same equal to the pressure of the main pump that is obtained from the oil pressure sensor.

Description

Hydraulic circuit of construction machinery

The disclosure is directed to a hydraulic circuit of a construction machine that can increase the operability while increasing the engine efficiency of the construction machine to further improve the performance of the work.

Preferred hydraulic circuits for construction machinery should maximize the output of the engine to increase work efficiency, and set maximum output in advance according to the type of work or the size of load to minimize unnecessary energy loss.

As shown in FIG. 1, the hydraulic circuit of a general construction machine performs a predetermined operation while the hydraulic actuator connected to the equipment is operated through a main control valve connected to the hydraulic pump according to the driving of the hydraulic pump connected to the engine. Through the ECU, the amount of hydraulic oil supplied from the hydraulic pump and the engine speed are controlled, and the pressure of the hydraulic circuit is protected by a relief valve.

Here, when the hydraulic pump is a variable displacement type, the supply flow rate supplied from the hydraulic pump to the hydraulic actuator may be represented by the product of the engine speed and the volume of one revolution of the hydraulic pump, and the volume of the hydraulic pump is the swash plate warp angle. It changes with the change.

This can be represented by the formula, Q = q × N.

(Q = supply flow rate of the hydraulic pump, q = volume per revolution of the hydraulic pump, N = engine speed)

On the other hand, in terms of the efficiency of the engine, the hydraulic circuit of the conventional construction machine and the hydraulic pump and the engine is not effectively controlled, which has a problem that the efficiency of the engine is reduced while the use area of the engine is limited.

In order to increase engine efficiency, reducing engine speed and using expensive high-capacity hydraulic pump with a large volume per revolution (q) can increase engine efficiency, but at the present cost, A low capacity hydraulic pump with a small volume q per revolution is used.

 By using a low capacity hydraulic pump with a small volume per revolution (q) and increasing the efficiency of the engine, the volume of the hydraulic pump per revolution (q) is increased, and the engine speed N is reduced to reduce the engine usage area. There is also a high control method.

However, this method is a low load of the construction machine, that is, when the volume (q) per one revolution of the hydraulic pump is reduced, the engine speed (N) is lowered when the supply flow rate (Q) of the hydraulic pump together As it decreases, the working speed of the construction machine is reduced, and the operation performance is deteriorated as the operability becomes poor.

Therefore, the contents described are proposed to solve the above-mentioned problems. When the supply flow rate of the hydraulic pump is insufficient according to the low load situation of the construction machine, the additional work flow rate is further provided to increase the working speed in the low load situation and the operability. It includes the purpose of providing a hydraulic circuit of the construction machine to improve the performance, so that the work performance can be further doubled.

According to a preferred embodiment of the present invention, a main pump and an auxiliary pump driven by an engine, a hydraulic actuator supplied with hydraulic oil through a supply flow path of the main pump, and a supply flow path between the main pump and the hydraulic actuator are installed A main control valve is installed to control the start, stop and direction change of the hydraulic actuator.

A hydraulic sensor for detecting the pressure of the main pump is installed in the supply passage of the main pump.

The joining flow path extending to one side from the supply flow path of the auxiliary pump is connected to the downstream side of the hydraulic sensor among the supply flow paths of the main pump, and the opening flow is controlled by the current value applied during the flow path of the main pump. An electric proportional valve is installed to control the flow rate of confluence into the supply flow path.

The drain flow path extending from the supply flow path of the auxiliary pump to the other side is connected to the hydraulic tank. During the drain flow path, the pressure of the main pump obtained from the hydraulic sensor installed in the supply flow path of the main pump and the pressure of the auxiliary pump are kept the same. Variable relief valves are installed and configured.

More preferably, it is possible to output to the variable relief valve so that the pressure of the main pump and the auxiliary pump inputted from the mode selector and the hydraulic sensor that receive the command related to the supply flow rate to be supplied to the hydraulic actuator can be kept the same. The controller further includes an ECU that determines a current value, and determines a current value to be output to the electric proportional valve to determine the flow rate of the auxiliary pump based on the value input from the mode selector.

The hydraulic circuit of the construction machine according to the description has the following effects.

That is, the contents described are the flow rate required for the performance of the specific work as the hydraulic oil of the auxiliary pump additionally installed when the flow rate of the rock pump is insufficient when the construction machine performs the specific work under the low load. It is configured to ensure that it is possible to prevent the fall of the work speed even under low load conditions of construction machinery.

In addition, it is possible to further improve work performance through improved operability.

In addition, it increases the efficiency of the engine to reduce fuel consumption, and has the effect of preventing the degradation of durability in advance.

The effects of the contents described above are naturally exerted by the composition of the contents described regardless of whether the inventor recognizes them. Therefore, the above-described effects are only a few effects according to the contents described, and describe all the effects grasped or found by the inventors. It should not be recognized.

And the effect of the contents described should be further grasped by the entire description of the specification, even if not described in explicit sentences even those having ordinary knowledge in the technical field to which the description belongs belong to such effects through this specification. If it is an acceptable effect, it should be seen as an effect described in this specification.

1 is a view showing a hydraulic circuit applied to a conventional construction machine.

2 is a view illustrating a hydraulic circuit of a construction machine according to an embodiment of the present disclosure.

3 is a view illustrating a hydraulic circuit of a construction machine according to another embodiment of the present disclosure.

4 is a perspective view illustrating a construction machine to which a hydraulic circuit according to an embodiment of the present disclosure is applied.

Hereinafter, preferred embodiments of the described contents will be described in detail with reference to the accompanying drawings.

This is intended to explain in detail enough to enable one skilled in the art to easily describe the described contents, which does not mean that the technical spirit and scope of the described contents are limited.

In addition, the size or shape of the components shown in the drawings may be exaggerated for clarity and convenience of description, terms specifically defined in consideration of the configuration and operation of the contents described will vary depending on the intention or custom of the user or operator And definitions for these terms should be made based on the contents described throughout this specification.

First, a hydraulic circuit of a construction machine according to an embodiment of the present disclosure will be described in detail with reference to FIG. 2.

The hydraulic circuit according to the description is a variable displacement main pump 110, constant displacement auxiliary pump 120, hydraulic actuator (not shown), the main control valve 140, the hydraulic sensor 150, the joining flow path ( 430, the electric proportional valve 160, the variable relief valve 170, and the ECU 180.

The variable displacement main pump (hereinafter referred to as main pump) 110 is connected to the drive shaft of the engine 300 and is driven together according to the driving of the engine 300, and the main pump through control of the swash plate tilt angle provided therein. The supply flow rate supplied from the 110 to the hydraulic actuator is varied. Typically it can be a piston pump.

A fixed capacity auxiliary pump (hereinafter referred to as an auxiliary pump) 120 is connected to the drive shaft of the engine 300, and the flow rate discharged from the auxiliary pump 120 is constant.

The auxiliary pump 120 serves to supplement the insufficient supply flow rate of the main pump 110 according to the low load state of the construction machine, it may be representatively a gear pump.

The main pump 110 and the auxiliary pump 120 may be configured in plurality according to the specifications of the construction machine.

Since the main pump 110 and the auxiliary pump 120 according to the description is applied to a pump that is generally used in construction machinery, a more detailed description thereof will be omitted.

The hydraulic actuator is connected to the supply passage 410 end of the main pump 110, it is operated by the operating oil supplied from the main pump (110).

The hydraulic actuator includes a hydraulic cylinder for operating equipment such as a boom, an arm, a bucket, and the like, and a hydraulic motor for obtaining turning or driving motion.

The main control valve 140 is installed in the supply passage 410 connecting the main pump 110 and the hydraulic actuator, and controls the start, stop, and direction change of the hydraulic actuator.

The hydraulic sensor 150 is installed in the supply passage 410 of the main pump 110 and detects the pressure to the main pump 110.

The joining passage 430 extends from the supply passage 420 of the auxiliary pump 120 and is connected to the supply passage 410 of the main pump 110.

The joining flow passage 430 is preferably connected to the downstream side of the hydraulic sensor 150 of the supply flow passage 410 of the main pump 110, which is the hydraulic oil discharged from the auxiliary pump 120 upstream of the hydraulic sensor 150 This is because, when joined in the above-mentioned hydraulic sensor 150 can not accurately detect the pressure according to the supply flow rate discharged from the main pump (110).

The electric proportional valve 160 is installed in the joining passage 430 extending from the supply passage 420 of the auxiliary pump 120 and connected to the supply passage 410 of the main pump 110, and in the auxiliary pump 120. The combined flow rate, which is the hydraulic oil discharged, is controlled to selectively replenish the supply passage 410 of the main pump 110.

The electric proportional valve 160 has a necessary opening degree adjusted according to the current value applied from the ECU 180, which will be described later, and the joining flow rate of the auxiliary pump 120 determined according to the adjusted opening degree of the main pump 110 is determined. The supply passage 410 is supplied.

When the combined flow rate discharged from the auxiliary pump 120 is joined to the supply flow path 410 of the main pump 110 through the control of the electric proportional valve 160 may include a low load state of the construction machine.

In this case, the low load state of the construction machine is reduced as the supply flow rate is reduced as the number of revolutions of the engine 300 is lowered, the operation speed may be poor, and the operability may be poor.

The variable relief valve 170 controls the pressure of the auxiliary pump 120 to be equal to the pressure of the main pump 110.

The variable relief valve 170 is installed in the drain passage 440 extending from the supply passage 420 of the auxiliary pump 120 and connected to the hydraulic tank 500.

The variable relief valve 170 has an opening degree adjusted according to a current value applied from the ECU 180, which will be described later, and the pressure of the main pump 110 and the auxiliary pump 120 determined by the above-described hydraulic sensor 150. Control the pressure equally).

ECU 180 is connected to the rotation sensing means (not shown in the figure) provided in the engine 300 to determine the rotation speed of the engine 300, the hydraulic sensor installed in the supply passage 410 of the main pump 110 Is connected to 150 to determine the pressure of the main pump (110).

The ECU 180 is installed in the main pump 110 and connected to the regulator 130 for controlling the swash plate tilt angle, and the supply passage 410 from the main pump 110 through the swash plate tilt angle control through the regulator 130. Determine the amount of supply flow discharged to the furnace.

The ECU 180 adjusts the respective openings through the output of the current values to the above-described electric proportional valve 160 and the variable relief valve 170 to adjust the pressure of the auxiliary pump 120 to the pressure of the main pump 110. Maintain the same as, and determines the amount of confluence flow rate that is joined to the supply passage 410 of the main pump 110 in the auxiliary pump (120).

The ECU 180 adjusts the opening degree by outputting a current value to the electric proportional valve 160, and an actuator (not shown) connected to a device selected by the driver in a low load situation of a construction machine is provided with a predetermined load. While performing a specific task requiring a specific flow rate, the flow rate required by the actuator for the specific task is compared with the supply flow rate supplied from the main pump 110 to the supply passage 410 in a low load situation. When it is determined, the opening degree of the electric proportional valve is adjusted to join the predetermined flow rate of the discharge flow from the auxiliary pump 120 to the supply flow path 410 of the main pump 110.

In another embodiment, the ECU is an actuator (not shown in the drawing) connected to a device selected by the driver in a low load situation of a construction machine to perform a specific task requiring a predetermined load, which is required by the actuator for the specific task. When comparing the required flow rate and the supply flow rate supplied from the main pump 110 to the supply flow path, the flow rate is accurately calculated by subtracting the supply flow rate from the required flow rate, and then adjusting the opening degree of the electric proportional valve 160 to adjust the flow rate. The combined flow rate of the same auxiliary pump 120 may be configured to be supplied to the supply passage 410 of the main pump 110.

As described above, the ECU 180 may determine the shortage flow rate through the calculation of the required flow rate and the supply flow rate, and supply the combined flow rate equal to the shortage flow rate to the supply flow path 410 of the main pump 110, but construction Depending on the working environment of the machine and the nature and needs of the work, the combined flow rate more or less than the insufficient flow rate may be supplied to the supply passage 410 of the main pump 110.

Hydraulic circuit of a construction machine according to another embodiment of the described content is as illustrated in FIG.

In the hydraulic circuit according to another embodiment of the present disclosure, in the confluence of the confluence flow rate discharged from the auxiliary pump 220 into the supply flow passage 410 of the main pump 110, the confluence flow rate is an electric type according to an embodiment. Instead of controlling with the proportional valve 160, the auxiliary pump 220 is configured as a variable displacement type to the supply flow path 410 of the main pump 110 through the control of the swash plate tilt angle provided in the auxiliary pump 200. It is to be able to control the combined flow rate of the auxiliary pump 220 to be joined.

The hydraulic circuit according to another embodiment of the present disclosure has the same configuration as the hydraulic circuit according to the above-described embodiment except that the auxiliary pump 220 is configured as a variable displacement type and there is no electric proportional valve 160. Therefore, the description of the components overlapping with the components of the hydraulic circuit according to the above-described embodiment will be omitted.

In the hydraulic circuit according to another embodiment of the present disclosure, a check valve 230 may be further installed among the joining flow passages 430 joined to the supply flow passage 410 of the main pump 110, and the check valve 230 may be In a situation where the construction machine is not a low load, the supply flow rate of the main pump 110 may be prevented from flowing back to the auxiliary pump 220.

On the other hand, in one embodiment as well as another embodiment of the contents described in the mode selection for receiving a command from the driver related to the joining flow rate of the auxiliary pump 120, 220 to the supply passage 410 of the main pump 110 Device 600 may further be included.

The mode selection device 600 may be divided into a low load working mode in which construction work is performed in a low load situation, and a non low load working mode, which may be referred to as a general working state of a construction machine.

That is, the driver may select a low load work mode and a non-low load work mode through the mode selector 600. When the driver selects the low load work mode because it is determined that the load required by the construction machine is small, the engine 300 As the rotation speed of the low) is adjusted, the supply flow rate of the main pump 110 is reduced.

Therefore, when the required flow rate for performing a specific operation in the low load situation of the construction machine exceeds the supply flow rate of the main pump 110 to generate a shortage flow rate to the confluence flow rate of the auxiliary pump (120, 220) You can supplement.

As described above, the mode selection device 600 may be configured in a manual manner in which a driver directly determines a low load of a construction machine and directly inputs a low load work mode, and the ECU 180 determines the low load of the construction machine. It can be configured in an automatic manner to carry out a low load operation mode.

Looking at the operation of the hydraulic circuit of the construction machine according to an embodiment of the described content configured as described above with reference to Figure 2 illustrated.

When the engine 300 is low and the required flow rate for operating the actuator connected to the device for the specific operation selected by the driver in the low load situation where the supply flow rate of the main pump 110 is insufficient, the ECU 180 Determining the supply flow rate of the main pump 110 through the required flow rate and the swash plate warp angle of the main pump 110.

The ECU 180 adjusts the opening degree of the electric proportional valve 160 to determine the combined flow rate discharged from the auxiliary pump 120 when it is determined that the required flow rate is larger than the supply flow rate. To be supplied).

Therefore, the actuator of the specific job having the required flow rate can be operated smoothly.

In this process, in order for the combined flow rate discharged from the auxiliary pump 120 to be supplied to the supply passage 410 of the main pump 110, the pressure of the main pump 110 and the auxiliary pump 120 sensed by the hydraulic sensor 150. The pressure of) must be the same to have utility.

Accordingly, the ECU 180 adjusts the set pressure by adjusting the opening degree of the variable relief valve 170 installed in the drain flow passage 440, thereby adjusting the pressure of the auxiliary pump 120 and the pressure of the main pump 110. Keeps the same.

Operation of the hydraulic circuit of the construction machine according to another embodiment of the described contents can be seen through the illustrated FIG.

Other embodiments In addition, when the required flow rate required by the actuator connected to the device for the specific operation selected by the driver in the low load situation of the construction machine as in the above-described embodiment, the ECU 180 determines the required flow rate and the main The supply flow rate of the main pump 110 is determined through the swash plate tilt angle of the pump 110.

The difference from the above-described embodiment is that when the ECU 180 determines that the required flow rate is greater than the supply flow rate, the discharge from the auxiliary pump 220 is controlled by adjusting the swash plate tilt angle of the variable capacity auxiliary pump 220. The flow rate is to be supplied to the supply passage 410 of the main pump 110.

Of course, by adjusting the opening pressure of the variable relief valve 170 installed in the drain flow path 440 to adjust the set pressure, the pressure of the auxiliary pump 220 and the pressure of the main pump 110 are maintained the same. Giving is the same as in one embodiment.

On the other hand, Figure 4 is a view illustrating a state in which the hydraulic circuit according to the description applied to the construction machine, Figure 4 illustrates an embodiment applied to the excavator, the hydraulic circuit according to the description described in the various including the excavator as shown in FIG. It can be applied in various forms to construction machinery.

In the detailed description of the contents described above, the method related to the specific embodiments has been described, but various modifications are possible without departing from the scope of the contents described.

In addition, the scope of the disclosed contents should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

The hydraulic circuit of the construction machine according to the description is based on the combined flow rate of the auxiliary pump which is additionally installed when the supply amount of the main pump is insufficient for the specific work under the condition that the supply amount of the main pump is insufficient according to the low load state of the construction machine. As it is configured to satisfy the required amount, it is very useful because it can increase the efficiency of the engine, save fuel efficiency, and improve the operability of construction machinery.

Claims (9)

A variable displacement main pump and a constant displacement auxiliary pump driven by the engine; A hydraulic actuator receiving hydraulic oil from the main pump; A main control valve installed between the main pump and the hydraulic actuator and controlling the operation of the hydraulic actuator; A hydraulic sensor installed in a supply flow path of the main pump and sensing a pressure of the main pump; A joining passage extending from a supply passage of the auxiliary pump and connected to a downstream side of the hydraulic sensor of the supply passage of the main pump; An electric proportional valve installed in the confluence flow path and configured to control the confluence flow rate by controlling an opening degree according to an applied current value; And And a variable relief valve installed in the drain flow path of the auxiliary pump and controlling the pressure of the auxiliary pump to be equal to the pressure of the main pump obtained from the hydraulic sensor. The method of claim 1, A mode selection device for receiving a command related to the flow rate to be supplied to the hydraulic actuator from the driver; And The pressure of the main pump is input from the hydraulic sensor to determine a current value to be output to the variable relief valve so as to remain the same as the pressure of the auxiliary pump, and based on the value received from the mode selection device. And an ECU for determining a current value to be output to the electric proportional valve so as to determine a confluence flow rate therefrom. The method of claim 2, The mode selection device, The low load operation mode and the non-low operation mode are divided into the low load operation mode. The auxiliary pump determines that the supply flow rate is low from the main pump to the hydraulic actuator and the engine speed is low. Hydraulic circuit for a construction machine configured to be joined to the flow rate of the main pump supply flow path. The method of claim 2, The mode selection device, The low load operation mode and the non-low operation mode are divided into the low load operation mode, and the main pump is supplied with the low flow rate supplied from the main pump to the hydraulic actuator and the engine speed is low. Calculate a difference between the supply flow rate supplied to the hydraulic actuator and the required flow rate required by the actuator for a predetermined operation, and then determine the insufficient flow rate, and the insufficient flow rate is configured to be supplemented through the combined flow rate of the auxiliary pump Hydraulic circuit for construction machinery. A variable displacement main pump and a variable displacement auxiliary pump driven by an engine; A hydraulic actuator receiving hydraulic oil from the main pump; A main control valve installed between the main pump and the hydraulic actuator and controlling the operation of the hydraulic actuator; A hydraulic sensor installed in a supply flow path of the main pump and sensing a pressure of the main pump; A joining passage extending from a supply passage of the auxiliary pump and connected to a downstream side of the hydraulic sensor of the supply passage of the main pump; And a variable relief valve installed in the drain flow path of the auxiliary pump and controlling the pressure of the auxiliary pump to be equal to the pressure of the main pump obtained from the hydraulic sensor. The method of claim 5, wherein A mode selection device for receiving a command related to the flow rate to be supplied to the hydraulic actuator from the driver; And The pressure of the main pump is input from the hydraulic sensor to determine a current value to be output to the variable relief valve so as to remain the same as the pressure of the auxiliary pump, and based on the value received from the mode selection device. And an ECU for determining a swash plate warp angle control signal of the auxiliary pump to determine a joining flow rate from the auxiliary pump. The method of claim 6, The mode selection device, The low load operation mode and the non-low operation mode are divided into the low load operation mode. The auxiliary pump determines that the supply flow rate is low from the main pump to the hydraulic actuator and the engine speed is low. Hydraulic circuit for a construction machine configured to be joined to the flow rate of the main pump supply flow path. The method of claim 6, The mode selection device, The low load operation mode and the non-low operation mode are divided into the low load operation mode, and the main pump is supplied with the low flow rate supplied from the main pump to the hydraulic actuator and the engine speed is low. Calculate a difference between the supply flow rate supplied to the hydraulic actuator and the required flow rate required by the actuator for a predetermined operation, and then determine the insufficient flow rate, and the insufficient flow rate is configured to be supplemented through the combined flow rate of the auxiliary pump Hydraulic circuit for construction machinery. The method according to claim 7 or 8, A check valve is installed in the joining flow path of the auxiliary pump joined to the supply flow path of the main pump to prevent the operating oil of the supply flow path from flowing back to the auxiliary pump through the joining flow path in the non-low load operation mode; Hydraulic circuit for machine.

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