Electrohydraulic control system, electrohydraulic control method and engineering machinery
Technical Field
The present invention relates to the field of electrohydraulic control. In particular, the present invention relates to electro-hydraulic control systems and electro-hydraulic control methods for work machines. The invention also relates to engineering machinery comprising the electrohydraulic control system.
Background
Work machines such as excavators, loaders, dozers, and the like are typically equipped with an electro-hydraulic control system for providing hydraulic fluid (e.g., hydraulic oil) to a hydraulic implement such as a swing motor, an oil cylinder, and the like in response to an operator's operation, thereby completing an action that the operator desires to perform.
Fig. 1 schematically shows an electro-hydraulic control system commonly used in a prior art construction machine, and fig. 3 schematically shows a hydraulic lock control method in the prior art electro-hydraulic control system.
As shown in fig. 3, the controller 4 is electrically connected to the open/open position of the hydraulic lock master switch 1 so as to detect an open signal of the hydraulic lock master switch 1 when the hydraulic lock master switch 1 is opened. Referring to fig. 1, after the engine is started, an operator opens the hydraulic lock master switch 1, a circuit is turned on, an electric signal turns on the hydraulic lock solenoid valve 3 through the hydraulic lock relay 2, and simultaneously the controller 4 detects an opening signal of the hydraulic lock master switch 1. The pilot oil from the pilot oil passage (pilot pump or pressure reducing valve) can reach the operation handle 6 through the hydraulic lock solenoid valve 3, thereby supplying the pilot hydraulic fluid required for the operation. The controller 4 sends electric signals to main spool control ports (electric controls) 7, 8 of a main pump 13 and a main valve 11 of the construction machine, and the main pump 13 and the main valve 11 are brought into an operating state. At this time, when the operation handle 6 is operated, pilot oil is supplied to the main spool control ports (pilot controls) 9, 10 at both ends of the main valve 11, and the main valve 11 is opened to supply hydraulic oil from the main pump 13 to the hydraulic actuator 12, thereby completing an operation that the operator wants to perform.
The electrohydraulic control system has certain defects in the aspect of safety.
On the one hand, when the hydraulic lock relay 2 is damaged, the electric signal cannot trigger the hydraulic lock electromagnetic valve 3 after the normally open hydraulic lock master switch 1 is opened. And because the controller 4 detects the opening signal of the hydraulic lock master switch 1, the controller 4 can judge that the machine works normally. However, the whole vehicle is not actually operated and thus cannot be reliably controlled.
On the other hand, when the hydraulic lock master switch 1 fails (at this time, the hydraulic lock master switch 1 is always in the off position) and the hydraulic lock relay 2 functions normally, if the current reaches the hydraulic lock relay 2 through some way, the electric signal turns on the hydraulic lock electromagnetic valve 3 through the relay 2. At this time, if the operation handle 6 or the like is accidentally touched or erroneously operated, the main valve 11 is caused to reverse, and each actuator 12 (such as a swing motor, an oil cylinder or the like) is erroneously operated, thereby causing a safety hazard.
The present invention is directed to solving the above-mentioned problems of the prior art.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides an electrohydraulic control system and an electrohydraulic control method for improving the whole vehicle operation safety of engineering machinery.
According to one aspect of the invention, it relates to an electro-hydraulic control system for a work machine, comprising:
a hydraulic lock master switch;
The hydraulic lock relay is electrically connected with the hydraulic lock main switch;
A hydraulic lock solenoid valve electrically connected to the hydraulic lock relay, and
A controller electrically connected with the main pump and the main valve of the construction machine so as to control actions of the main pump and the main valve,
Wherein the controller is configured to:
detecting a closing signal of a hydraulic lock master switch;
detecting an opening signal of a hydraulic lock relay;
When the controller does not detect the closing signal of the hydraulic lock master switch and detects the opening signal of the hydraulic lock relay, the controller sends electric signals to the main pump and the main valve so as to control the main pump and the main valve to be in an operating state.
In the electrohydraulic control system, the controller carries out logic relation judgment based on the closing/non-closing signal of the hydraulic lock master switch and the opening/closing signal of the hydraulic lock relay, and controls whether the main pump and the main valve need normal output according to the judgment result, thereby avoiding misoperation of an actuating mechanism caused by accidental touch or misoperation of an operating handle and the like, eliminating potential safety hazard, enhancing the safety control level, and realizing control and safety requirements with minimum cost.
Advantageously, the controller is electrically connected to the closed position of the hydraulic lock master switch to detect the closing signal of the hydraulic lock master switch, and
The controller is electrically connected to a position downstream of the hydraulic lock relay and upstream of the hydraulic lock solenoid valve to detect an open signal of the hydraulic lock relay.
Advantageously, the controller is configured to control the main pump and the main valve to be inactive when one of:
-the controller detects a closing signal of the hydraulic lock master switch and does not detect an opening signal of the hydraulic lock relay;
-the controller does not detect a closing signal of the hydraulic lock master switch and does not detect an opening signal of the hydraulic lock relay;
The controller detects a closing signal of the hydraulic lock master switch and an opening signal of the hydraulic lock relay.
Advantageously, when the hydraulic lock solenoid valve is energized, pilot hydraulic oil can be transferred to the operating handle.
According to another aspect of the invention, it relates to an electrohydraulic control method for a construction machine, the construction machine comprising:
a hydraulic lock master switch;
The hydraulic lock relay is electrically connected with the hydraulic lock main switch;
A hydraulic lock solenoid valve electrically connected to the hydraulic lock relay, and
A controller electrically connected with the main pump and the main valve of the construction machine so as to control actions of the main pump and the main valve,
The electro-hydraulic control method is characterized by comprising the following steps:
Detecting a closing signal of a hydraulic lock master switch through a controller;
detecting an opening signal of a hydraulic lock relay through a controller;
wherein when the controller does not detect the closing signal of the hydraulic lock master switch and detects the opening signal of the hydraulic lock relay, the controller sends an electric signal to the main pump and the main valve so as to put the main pump and the main valve in an operating state.
Advantageously, the controller is electrically connected to the closed position of the hydraulic lock master switch to detect the closing signal of the hydraulic lock master switch, and
The controller is electrically connected to a position downstream of the hydraulic lock relay and upstream of the hydraulic lock solenoid valve to detect an open signal of the hydraulic lock relay.
Advantageously, the controller controls the main pump and the main valve to be inactive in one of the following conditions:
-the controller detects a closing signal of the hydraulic lock master switch and does not detect an opening signal of the hydraulic lock relay;
-the controller does not detect a closing signal of the hydraulic lock master switch and does not detect an opening signal of the hydraulic lock relay;
The controller detects a closing signal of the hydraulic lock master switch and an opening signal of the hydraulic lock relay.
Advantageously, when the hydraulic lock solenoid valve is energized, pilot hydraulic oil is delivered to the operating handle.
According to another aspect of the invention, it relates to a working machine comprising an electro-hydraulic control system as described above.
Advantageously, the working machine is an excavator.
Drawings
Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying schematic drawings. The drawings and corresponding embodiments are for illustration purposes only and are not intended to limit the present invention. In the drawings:
figure 1 schematically illustrates an electro-hydraulic control system commonly used in prior art work machines,
Figure 2 schematically illustrates an electro-hydraulic control system for a work machine according to one embodiment of the invention,
FIG. 3 schematically illustrates a hydraulic lock control method in a prior art electro-hydraulic control system, and
Fig. 4 schematically illustrates a hydraulic lock control method in an electro-hydraulic control system according to the present invention.
Detailed Description
Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding and enabling description of the invention to one skilled in the art. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. Furthermore, it should be understood that the invention is not limited to specific described embodiments. Rather, any combination of the features and elements described below is contemplated to implement the invention, whether or not they relate to different embodiments. Thus, the aspects, features, embodiments and advantages described below are for illustrative purposes only and should not be construed as elements or limitations of the claims unless explicitly set forth in the claims.
Fig. 4 schematically illustrates a hydraulic lock control method in an electro-hydraulic control system according to the present invention. As shown in fig. 4, the controller 4 is electrically connected to the off position of the hydraulic lock master switch 1 to detect the off signal of the hydraulic lock master switch 1, on the one hand, and to a position downstream of the hydraulic lock relay 2 and upstream of the hydraulic lock solenoid valve 3 to detect the on signal of the hydraulic lock relay 2, on the other hand.
When the hydraulic lock master switch 1 is not opened, the hydraulic lock master switch 1 is in a normally closed position. At this time, the controller 4 detects a closing signal of the hydraulic lock master switch 1. As shown in fig. 2, when the hydraulic lock master switch 1 and the hydraulic lock relay 2 are both functioning normally, after the engine is started, when the operator opens the hydraulic lock master switch 1, the electric circuit is turned on, and the electric signal turns on the hydraulic lock solenoid valve 3 through the hydraulic lock relay 2. At this time, the controller 4 does not detect the off signal of the hydraulic lock master switch 1 (in other words, the controller 4 determines that the hydraulic lock master switch 1 is in the on state), while the controller 4 detects the on signal of the hydraulic lock relay 2. The controller 4 sends electric signals to main spool control ports (electric controls) 7, 8 of a main pump 13 and a main valve 11 of the construction machine so as to control the main pump 13 and the main valve 11 to be in an operating state. The pilot oil from the pilot oil passage (pilot pump or pressure reducing valve) is turned on for supplying the pilot hydraulic fluid required for the operation. At this time, when the operation handle 6 is operated, pilot oil is supplied to the main spool control ports (pilot controls) 9, 10 at both ends of the main valve 11, and the main valve 11 is opened to supply hydraulic oil from the main pump 13 to the hydraulic actuator 12.
According to the present invention, the controller 4 logically analyzes an electric signal (off or non-off signal) from the hydraulic lock master switch 1 and an electric signal (on or off signal) from the hydraulic lock relay 2, and the controller 4 transmits electric signals to the main pump and the main valve to control the main pump and the main valve to be in an operating state only when the controller 4 does not detect the off signal of the hydraulic lock master switch 1 and detects the on signal of the hydraulic lock relay 2.
Table 1 shows that the controller 4 performs logic analysis based on the states of the hydraulic lock master switch 1 and the hydraulic lock relay 2 and controls the main pump and the main valve according to the determination result.
Hydraulic lock master switch |
Hydraulic lock relay |
Controller for controlling a power supply |
Main pump and main valve |
OFF |
OFF |
OFF |
OFF |
ON |
OFF |
OFF |
OFF |
OFF |
ON |
OFF |
OFF |
ON |
ON |
ON |
ON |
TABLE 1
As shown in table 1, when the controller 4 detects the OFF signal from the hydraulic lock master switch 1, the controller 4 determines that the hydraulic lock master switch 1 is in the OFF state (OFF). When the controller 4 does not detect the off signal from the hydraulic lock master switch 1, the controller 4 determines that the hydraulic lock master switch 1 is in the ON state (ON). When the controller 4 detects the open signal of the hydraulic lock relay 2, it is determined that the hydraulic lock relay 2 is in the open/ON state (ON). When the controller 4 does not detect the open signal of the hydraulic lock relay 2, it is determined that the hydraulic lock relay 2 is in the OFF/disconnected state (OFF).
When the function of either one of the hydraulic lock master switch 1 and the hydraulic lock relay 2 fails or fails at the same time or feedback is in abnormal operation, the determination result given by the controller 4 through logic analysis is OFF, that is, the controller 4 determines that the machine is in a state of being unable to work normally, the controller 4 notifies the main pump 13 and the electric proportional pressure reducing valves 7 and 8 (electric control) which control the reversing of the main valve core at both ends of the main valve 11 to stop working, and the whole vehicle does not act. At this time, the main pump 13 and the main valve 11 are in a locked state, the main pump 13 is adjusted to a minimum output flow rate, and the main valve 11 does not respond to the pilot pressure and the control signal from the operation handle 6. Therefore, even if the operation handle 6 is erroneously operated or accidentally touched, no hydraulic oil enters the actuator, so that malfunction does not occur.
Only when the controller 4 determines that the hydraulic lock main switch 1 is in the open state (ON) and the hydraulic lock relay 2 is in the open/ON state (ON), the determination result given by the controller 4 through the logic analysis is ON, indicating that the hydraulic lock main switch 1 and the hydraulic relay 2 are functioning normally and the hydraulic lock main switch 1 is turned ON, the controller 4 sends electric signals to the main pump 13 and the main valve 11 so as to control the main pump and the main valve to be in the operating state. Thereby enhancing the safety control level of the control system.
In addition, if the controller 4 determines that the hydraulic lock master switch 1 is in the ON state (ON), but at the same time determines that the hydraulic lock relay 2 is in the OFF state (OFF), it indicates that the hydraulic lock relay 2 is malfunctioning.
According to the electrohydraulic control system disclosed by the invention, the controller 4 is electrically connected with the closing position of the hydraulic lock master switch 1 to transmit a feedback signal to the controller 4, and an electric wire is added between a position downstream of the hydraulic lock relay 2 and upstream of the hydraulic lock electromagnetic valve 3 and the controller 4 to transmit the feedback signal to the controller 4, the controller 4 makes a logic relation judgment based on the closing/non-closing signal of the hydraulic lock master switch 1 and the opening/closing signal of the hydraulic lock relay 2, and controls whether the main pump 13 and the main valve 11 need to normally output according to the judgment result, thereby avoiding misoperation, eliminating potential safety hazards, enhancing the safety control level, and realizing control and safety requirements with minimum cost. In addition, whether the hydraulic lock relay is damaged can be judged.
Industrial applicability
The electrohydraulic control system improves the safety of engineering machinery through simple structural improvement, and realizes the control and safety requirements with minimum cost. Such safety design logic is applicable to work machines such as excavators, loaders, and other types of machines having similar operating conditions requirements.
After the engine is started, when the operator opens the hydraulic lock master switch 1, the controller 4 controls the main pump 13 and the main valve 11 to be in a non-operating state in one of the following cases:
-the controller detects a closing signal of the hydraulic lock master switch and does not detect an opening signal of the hydraulic lock relay;
-the controller does not detect a closing signal of the hydraulic lock master switch and does not detect an opening signal of the hydraulic lock relay;
The controller detects a closing signal of the hydraulic lock master switch and an opening signal of the hydraulic lock relay.
The controller 4 controls the main pump 13 and the main valve 11 to be in an operating state if and only if the controller 4 does not detect the closing signal of the hydraulic lock master switch and detects the opening signal of the hydraulic lock relay.
The electro-hydraulic control system and method of the present invention has been described above with the aid of specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made to the above-disclosed embodiments without departing from the scope or spirit of the invention. For example, implementations of the invention may not include some of the specific features described, nor is the invention limited to the specific embodiments described, but any combination of the described features and elements is contemplated. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed electro-hydraulic control system and method. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.