Hydraulic pressure detection circuit, hydraulic system, excavator

Abstract

This invention relates to pressure detection circuits. To address the problem of pressure transmitters on existing construction machinery occupying a large number of pin interfaces on the controller, this invention constructs a hydraulic pressure detection circuit, a hydraulic system, and an excavator. The hydraulic pressure detection circuit includes a controller and at least two pressure switches. The first terminal of the circuit formed by the pressure switches connected in series is connected to the analog input pin of the controller, and the second terminal is connected to the positive terminal of the power supply. Each pressure switch is connected in parallel with a resistor, and the resistance values ​​of any combination of these resistors in series are different. This invention occupies only one analog input pin of the controller, enabling pressure monitoring at multiple pressure monitoring points, thus minimizing pin usage.

Description

Technical Field

[0001] This invention relates to a pressure detection circuit, and more specifically, to a hydraulic pressure detection circuit, a hydraulic system, and an excavator. Background Technology

[0002] In engineering machinery, during the control of the machine, it is necessary to obtain the pressure parameters of many oil circuit nodes in its hydraulic system. Pressure detection is usually achieved using pressure transmitters such as pressure sensors or pressure switches, with each pressure transmitter connected to an analog input interface of the controller.

[0003] As construction machinery evolves towards electronic and intelligent control, controllers require a large number of analog input signals. Existing controllers lack sufficient pins to meet complex electronic control needs. Adding more pins would require developing a new controller, increasing costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the pressure transmitters used in existing engineering machinery occupy a lot of controller pin interfaces. The present invention provides a hydraulic pressure detection circuit, hydraulic system and excavator, so that the pressure transmitter for detecting hydraulic pressure occupies fewer controller pin interfaces.

[0005] The technical solution of this invention to achieve its objective is as follows: A hydraulic pressure detection circuit is constructed, characterized by including a controller and at least two pressure switches. The first terminal of the circuit formed by the pressure switches connected in series is connected to the analog input pin of the controller, and the second terminal is connected to the positive terminal of a power supply. Each pressure switch is connected in parallel with a resistor, and the resistance values ​​of any combination of the resistors are different. The sum of the resistance values ​​of any combination of the resistors refers to the sum of the resistance values ​​of any number of resistors selected from all the resistors connected in parallel with the pressure switches.

[0006] In this invention, each pressure switch is configured at a corresponding pressure monitoring point. When the pressure at the monitoring point reaches the set value of the pressure switch, the pressure switch closes, and the resistor connected in parallel with it is short-circuited by the pressure switch. The combination of each pressure switch being in an open or closed state results in different total resistance values ​​of the un-short-circuited resistors connected in series between the positive terminal of the power supply and the analog input pin of the controller, leading to different potentials presented on the analog input pin of the controller. The controller determines whether the pressure at each pressure monitoring point has reached the predetermined value based on the potential on the analog input pin and the open or closed state of each pressure switch.

[0007] In this invention, the controller can detect the pressure of multiple pressure monitoring points using a single analog input pin, thus requiring fewer analog input pins on the controller.

[0008] In the hydraulic pressure detection circuit of the present invention, the number of pressure switches is two to five, used to monitor the pressure of five pressure monitoring points. The number of pressure switches is preferably three. Further, the ratio of the resistors connected in parallel with the three pressure switches is 1:2:4, or 1:2:5, or 1:1.5:2.

[0009] In the hydraulic pressure detection circuit of this invention, the voltage at the positive terminal of the power supply is 5 volts.

[0010] The technical solution of this invention to achieve its objective is as follows: A hydraulic system is constructed, characterized by having the aforementioned hydraulic pressure detection circuit. In this invention, the controller uses a single analog input pin to detect whether the pressure at multiple pressure monitoring points in the hydraulic system has reached a predetermined value, thus requiring fewer analog input pins on the controller.

[0011] The technical solution of this invention to achieve its objective is as follows: A hydraulic system for an excavator is constructed, including an auxiliary pilot valve, a right-hand pilot valve, and a left-hand pilot valve. The two pilot output ports of the auxiliary pilot valve are connected to the two inlet ports of a first shuttle valve; the two pilot output ports of the right-hand pilot valve are connected to the two inlet ports of a second shuttle valve; and the two pilot output ports of the left-hand pilot valve are connected to the two inlet ports of a third shuttle valve. The hydraulic system is characterized by further having the aforementioned hydraulic pressure detection circuit, wherein the three pressure switches are respectively configured to detect the pressure at the outlet ports of the first, second, and third shuttle valves. Further, the working pump of the hydraulic system is an electrically controlled displacement piston pump, and its electrical control terminal is electrically connected to the controller.

[0012] The technical solution of the present invention to achieve its purpose is as follows: to construct an excavator, characterized by having the aforementioned hydraulic system.

[0013] Compared with the prior art, the present invention occupies only one analog input pin of the controller, but can realize pressure monitoring of multiple pressure monitoring points, thus occupying fewer pins. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the hydraulic pressure detection circuit of the present invention.

[0015] Figure 2 This is a schematic diagram of the hydraulic system in the excavator of this invention.

[0016] Component names and serial numbers in the diagram:

[0017] Controller 1, First pressure switch 2, Second pressure switch 3, Third pressure switch 4, First resistor 5, Second resistor 6, Third resistor 7, Power supply positive terminal 8, First working pump 21, Main valve 22, Auxiliary main valve 23, Right travel main valve 24, Auxiliary attachment 25, Auxiliary pilot valve 26, Right travel pilot valve 27, Left travel pilot valve 28, First shuttle valve 29, Second shuttle valve 30, Third shuttle valve 31, Pilot pump 32. Detailed Implementation

[0018] The specific implementation plan is described below with reference to the attached diagram.

[0019] Example 1.

[0020] Figure 1 A schematic diagram of the hydraulic pressure detection circuit of this invention is shown. In this hydraulic pressure detection circuit, as... Figure 1 As shown, it includes a controller 1, a first pressure switch 2, a second pressure switch 3, and a third pressure switch 4. The three pressure switches are connected in series to form a circuit. The first terminal of the circuit is connected to the analog input pin 1 of the controller, and the second terminal is connected to the positive terminal 8 of the power supply, which typically has a voltage of 5 volts. Each pressure switch is connected in parallel with a resistor; that is, the first pressure switch 2 is connected in parallel with the first resistor 5, the second pressure switch 3 is connected in parallel with the second resistor 6, and the third pressure switch 4 is connected in parallel with the third resistor 7. The resistance values ​​of each resistor can be varied in any combination. For example, in this embodiment, the resistance values ​​of the first resistor 5, the second resistor 6, and the third resistor 7 are 1R, 2R, and 5R, respectively, meaning the resistance ratio of the three resistors is 1:2:5.

[0021] Each pressure switch is used to detect the pressure at the hydraulic monitoring point. When the pressure at the monitoring point is greater than or equal to the set pressure of the pressure switch at that monitoring point, the pressure switch closes and the resistor connected in parallel with the pressure switch is short-circuited.

[0022] In the controller, the analog input pins are all connected to grounding voltage divider resistors. When different resistors are connected between the analog input pins of the controller and the positive terminal of the power supply, different voltages will be applied to the analog input pins due to the effect of the grounding voltage divider resistors.

[0023] In this embodiment, there are three pressure switches, each with two states: open and closed, resulting in eight possible combinations: all closed, two closed and one open (three combinations), two open and one closed (three combinations), and all open. Corresponding to these eight combinations, the three resistors also have eight possible combinations. The sum of the resistance values ​​between the positive terminal of the power supply and the analog input pin of the controller under these eight combinations is 0R, 1R, 2R, 5R, 3R, 6R, 7R, and 8R (where R is a resistor value). Since the resistance values ​​are different for each of the eight combinations, the voltage at the analog input pin of the controller is different in any combination compared to other combinations. Therefore, the controller can determine the combination of the three pressure switches based on the voltage at its analog input pin, thus determining the open or closed state of each switch and consequently the pressure status of the three pressure monitoring points.

[0024] In this embodiment, the resistance ratio of the first resistor 5, the second resistor 6, and the third resistor 7 can also be other ratios, such as 1:2:4 or 1:1.5:2.

[0025] In this embodiment, the number of pressure switches can be set according to the number of pressure monitoring points. It can be two or more, but usually two to five.

[0026] Example 2.

[0027] Figure 2 A schematic diagram of the hydraulic system in an excavator according to an embodiment of the present invention is shown. In this excavator, the hydraulic system includes a first working pump 20, a second working pump 21, and a pilot pump 32. The second working pump 21 is connected to the right-moving control main valve 24 and the auxiliary control main valve 23 in the main valve 22, supplying them with hydraulic oil for operation. As needed, the second working pump 21 can also supply oil to other control main valves in the main valve, such as the swing control main valve, boom control main valve, and stick control main valve. The first working pump 20 supplies oil to the left-moving control main valve, stick control main valve, bucket control main valve, boom control main valve, and straight-line travel control main valve (other main valves are not shown in the diagram).

[0028] Both the first working pump 20 and the second working pump 21 are electronically controlled variable displacement piston pumps, controlled by the controller 1. The controller 1 outputs control commands based on the working conditions of the excavator, which drive the swashplates in the proportional solenoid valves of the first working pump 20 and the second working pump 21 to actuate, so that the corresponding working pump outputs the required flow rate. The pilot pump 32 is connected to the inlet of each pilot valve so that when the pilot valve is operated, its pilot output port outputs pilot pressure oil.

[0029] like Figure 1As shown, in the excavator, the control main valves of hydraulic actuators such as the auxiliary attachment 25, the left travel motor, and the right travel motor (not shown in the figure) adopt pilot-operated hydraulic control. Specifically, the two pilot output ports of the auxiliary pilot valve 26 are connected to the two pilot hydraulic control terminals of the auxiliary control main valve 23, the two pilot output ports of the right travel pilot valve 27 are connected to the two pilot hydraulic control terminals of the left travel control main valve 24, and the two pilot output ports of the left travel pilot valve 28 are connected to the two pilot hydraulic control terminals of the left travel control main valve (not shown in the figure). The valve stem of each pilot valve is connected to a corresponding pedal. By pressing the corresponding pedal, the corresponding pilot valve can output pilot pressure oil, driving the corresponding control main valve to switch directions.

[0030] Each of the auxiliary pilot valves 26, 27 (right-hand pilot valve), and 28 (left-hand pilot valve) has two pilot output ports, resulting in a total of six pilot pressure oil circuits. The two pilot output ports of the auxiliary pilot valve 26 are connected to the two inlet terminals of the first shuttle valve 29, the two pilot output ports of the right-hand pilot valve 27 are connected to the two inlet terminals of the second shuttle valve 30, and the two pilot output ports of the left-hand pilot valve 28 are connected to the two inlet terminals of the third shuttle valve 31. Each of the first shuttle valve 29, second shuttle valve 30, and third shuttle valve 31 has a pressure switch at its outlet terminal. When the pressure at the set point of the pressure switch is greater than or equal to the set value, the pressure switch changes from an open state to a closed state.

[0031] When the operator presses the pedal, the corresponding pilot valve outputs pilot pressure oil from one of its two pilot pressure oil circuits. This pilot pressure is transmitted to the outlet of the corresponding shuttle valve, acting on the corresponding pressure switch and causing it to close. Therefore, by detecting whether the pressure switch is in the closed state, it can be determined whether the corresponding pilot valve has been operated, thereby determining whether the excavator is performing a certain operation. In the existing technology, the pressure switches at the outlets of the first shuttle valve 29, the second shuttle valve 30, and the third shuttle valve 31 are each connected to the controller, occupying three analog input pins of the controller, often resulting in the controller's pins not meeting the machine controller's requirements.

[0032] In the hydraulic system of this embodiment, there is a hydraulic pressure detection circuit as in Embodiment 1. The first pressure switch 2, the second pressure switch 3, and the third pressure switch 4 of the hydraulic pressure detection circuit are arranged sequentially at the oil outlet end of the first shuttle valve 29, the oil outlet end of the second shuttle valve 30, and the oil outlet end of the third shuttle valve 31. When the pressure at the oil outlet end of the shuttle valve is greater than or equal to a predetermined value, the pressure switch arranged at the oil outlet end of the shuttle valve closes.

[0033] In this embodiment, the excavator's operation action recognition process is as follows:

[0034] 1. Only auxiliary attachments are activated. The auxiliary pilot valve is operated and is in the fully open state. The pilot pressure output from one of its pilot output ports closes the first pressure switch, while the second and third pressure switches are both in the open state. The resistance between the positive terminal of the power supply and the analog input pin of the controller is 7R (the sum of the resistance values ​​of the second and third resistors). The controller infers that only the auxiliary attachments are activated based on the magnitude of the voltage divider signal at the analog input pin.

[0035] 2. Only right-moving action is performed. The right-moving pilot valve is operated and is in the fully open state. The pilot pressure output from one of its pilot output ports causes the second pressure switch to close, while the first and third pressure switches are both in the open state. The resistance between the positive terminal of the power supply and the analog input pin of the controller is 6R (the sum of the resistance values ​​of the first and third resistors). The controller infers that only right-moving action is performed based on the magnitude of the voltage divider signal at the analog input pin.

[0036] 3. Only leftward movement is performed. The leftward pilot valve is operated and is in the fully open state. The pilot pressure output from one of its pilot output ports causes the third pressure switch to close, while the first and second pressure switches are both in the open state. The resistance between the positive terminal of the power supply and the analog input pin of the controller is 3R (the sum of the resistance values ​​of the first and second resistors). The controller infers that only leftward movement is performed based on the magnitude of the voltage divider signal at the analog input pin.

[0037] 4. The auxiliary attachment action and the right-walking action are performed simultaneously (left-walking action is not performed). The auxiliary pilot valve and the right-walking pilot valve are operated and are in the fully open state. The pilot pressure output by the two pilot valves closes the first pressure switch and the second pressure switch respectively, and the third pressure switch is in the open state. The resistance between the positive terminal of the power supply and the analog input pin of the controller is 5R (the resistance value of the third resistor). The controller infers that the auxiliary attachment action and the right-walking action are performed simultaneously based on the magnitude of the voltage divider signal at the analog input pin.

[0038] 5. The auxiliary attachment action and the left travel action are performed simultaneously (the right travel action is not performed). The auxiliary pilot valve and the left travel pilot valve are operated and are in the fully open state. The pilot pressure output by the two pilot valves causes the first pressure switch and the third pressure switch to close respectively, and the second pressure switch is in the open state. The resistance between the positive terminal of the power supply and the analog input pin of the controller is 2R (the resistance value of the second resistor). The controller infers that the auxiliary attachment action and the left travel action are performed simultaneously based on the magnitude of the voltage divider signal at the analog input pin.

[0039] 6. The left and right walking actions are performed simultaneously (without auxiliary attachment actions). The pilot pressure output by the two pilot valves closes the second and third pressure switches respectively, while the first pressure switch is in the open state. The resistance between the positive terminal of the power supply and the analog input pin of the controller is 1R (the resistance value of the first resistor). The controller infers that the left and right walking actions are performed simultaneously based on the magnitude of the voltage divider signal at the analog input pin.

[0040] 7. The auxiliary attachment action, left travel action, and right travel action are performed simultaneously. The pilot pressure output by the three pilot valves causes the first pressure switch, the second pressure switch, and the third pressure switch to close or close respectively. The resistance between the positive terminal of the power supply and the analog input pin of the controller is 0R (all three resistors are short-circuited). The controller infers that the auxiliary attachment action and the left and right travel actions are performed simultaneously based on the magnitude of the voltage divider signal at the analog input pin.

[0041] 8. The auxiliary attachment, left travel, and right travel actions are not performed. All three pressure switches are in the open state. The resistance between the positive terminal of the power supply and the analog input pin of the controller is 8R (the sum of the resistance values ​​of the three resistors). The controller infers that the auxiliary attachment, left travel, and right travel actions are not performed based on the magnitude of the voltage divider signal at the analog input pin.

[0042] In this embodiment of the excavator, the hydraulic pressure detection circuit uses three pressure switches, occupying one analog input pin of the controller. This allows the excavator hydraulic system controller to identify the attachment movement, left travel movement, and right travel movement through the electrical signal obtained from one analog input pin, thus saving the limited number of analog input pins on the controller.

Claims

1. A hydraulic system for an excavator, comprising an auxiliary pilot valve, a right-travel pilot valve, and a left-travel pilot valve, characterized in that, It also includes a hydraulic pressure detection circuit, wherein the two pilot output ports of the auxiliary pilot valve are connected to the two inlet ports of the first shuttle valve, the two pilot output ports of the right-hand pilot valve are connected to the two inlet ports of the second shuttle valve, and the two pilot output ports of the left-hand pilot valve are connected to the two inlet ports of the third shuttle valve; the hydraulic pressure detection circuit includes a controller and three pressure switches, the first end of the circuit formed by the pressure switches connected in series is connected to the analog input pin of the controller, and the second end is connected to the positive terminal of the power supply; each pressure switch is connected in parallel with a resistor, and the resistance values ​​of any combination of the resistors are different; The three pressure switches are respectively configured to detect the oil outlet pressure of the first shuttle valve, the second shuttle valve, and the third shuttle valve; The voltage at the positive terminal of the power supply is 5 volts; The working pump of the hydraulic system is an electrically controlled displacement piston pump, and its electrical control terminal is electrically connected to the controller.

2. The hydraulic system according to claim 1, characterized in that, The ratio of the resistors connected in parallel with the three pressure switches is 1:2:4, or 1:2:5, or 1:1.5:

2.

3. An excavator, characterized in that... A hydraulic system having any one of claims 1 to 2.

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