CN111852973A - Control method of hydraulic system of compression mechanism of rear-mounted compression type garbage truck - Google Patents
Control method of hydraulic system of compression mechanism of rear-mounted compression type garbage truck Download PDFInfo
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- CN111852973A CN111852973A CN202010745051.2A CN202010745051A CN111852973A CN 111852973 A CN111852973 A CN 111852973A CN 202010745051 A CN202010745051 A CN 202010745051A CN 111852973 A CN111852973 A CN 111852973A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/20—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors controlling several interacting or sequentially-operating members
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/08—Servomotor systems incorporating electrically operated control means
- F15B21/087—Control strategy, e.g. with block diagram
Abstract
A control method of a hydraulic system of a compression mechanism of a rear-mounted compression type garbage truck. The invention discloses a control method for reducing overflow protection time of a hydraulic system, in one working stroke of a hydraulic cylinder, when a system pressure value is greater than a set value P2, a PLC (programmable logic controller) electric control unit calculates an instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is less than a set value A0, namely the rising speed of the system pressure is low, the hydraulic cylinder is determined to move to the maximum stroke position, the PLC electric control unit sends an instruction to enable a corresponding electromagnet to be uncharged, and oil supply is stopped.
Description
[ technical field ] A method for producing a semiconductor device
The application is a divisional application of a patent application with the application date of 2019, 7 and 22, the application number of 201910661653.7 and the name of 'a control method for reducing overflow protection time of a hydraulic system'.
[ background of the invention ]
The hydraulic cylinder is used as an important executing mechanism in a hydraulic system, the application of the hydraulic cylinder is very wide, for the hydraulic system, the control of starting-stopping-reversing-retracting-stopping of the hydraulic cylinder directly influences the action efficiency of the hydraulic cylinder, and meanwhile, the reversing time directly influences the time of high-pressure overflow (the high-pressure overflow refers to the phenomenon that a piston rod of the hydraulic cylinder moves to a limit position and continues to supply oil, and the high-pressure overflow is not reversed, and because of the protection mechanism of the hydraulic system, the higher the high-pressure overflow time is, the larger the calorific value is, the larger the useless work of the hydraulic system is, and the lower the efficiency of the hydraulic system is; meanwhile, the operation cycle is prolonged, the beat is reduced, and the operation efficiency of the mechanism is reduced.
For a hydraulic system adopting a travel switch to control reversing, the phenomenon of high-pressure overflow is basically avoided, because the piston moves in place, namely reversing is carried out, the high-pressure overflow time is extremely short, but the travel switch cannot be used in some cases, for example, an actuating mechanism bears a large load, and deformation occurs in a long time, so that the travel switch fails; therefore, the invention adopts a pressure relay to control the reversing of the hydraulic cylinder.
Fig. 7 is a diagram of the relationship between the system pressure and the time during the operation of the hydraulic system of the compression mechanism of the existing rear-loading compression garbage truck, the compression mechanism comprises the comprehensive movements of four actions of opening and closing of the scraper and the upward and downward movement of the slide block, and the comprehensive movements are circularly executed according to the sequence of 'scraper opening, slide plate downward movement, scraper closing and slide plate upward movement', and the control principle of the existing compression mechanism is now explained by combining fig. 7:
the first step is as follows: the electromagnet DT1 is electrified, the scraper begins to open, after 0.3 second, the PLC electronic control unit begins to receive and process a system pressure value Pt detected by the pressure relay, when Pt is larger than a set value P2 (corresponding to time T1), the electromagnet DT1 is not electrified after 0.6 second delay, the electromagnetic valve A resets, and the scraper opens to the maximum position;
the second step is that: the electromagnet DT4 is electrified (corresponding to time T1+0.6 seconds), the sliding plate starts to descend, after 0.3 seconds (corresponding to time T1+0.9 seconds), the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay, when the Pt is greater than a set value P2 (corresponding to time T2), the electromagnet DT4 is not electrified after 0.6 second delay, the electromagnetic valve B is reset, and the sliding plate descends to the maximum position;
the third step: the electromagnet DT2 is electrified (corresponding to time T2+0.6 seconds), the scraper starts to be scraped, after 0.3 second (corresponding to time T2+0.9 seconds), the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay, when the Pt is greater than a set value P2 (corresponding to time T3), the electromagnet DT2 is not electrified after 0.6 second delay, the electromagnetic valve A is reset, and the scraper starts to be scraped to the initial position;
the fourth step: the electromagnet DT3 is electrified (corresponding to time T3+0.6 seconds), the sliding plate starts to descend, after 0.3 seconds (corresponding to time T3+0.9 seconds), the PLC electronic control unit starts to receive and process a system pressure value Pt detected by the pressure relay, when the Pt is larger than a set value P2 (corresponding to time T4), the electromagnet DT3 is not electrified after 0.6 seconds of delay, the electromagnetic valve B is reset, and the sliding plate ascends to the initial position.
In summary, in each stroke (extending or retracting) of the two hydraulic cylinders, the oil supply to the hydraulic cylinder is stopped only after the system pressure value Pt detected by the relay is larger than the set value P2 and is delayed for a period of time, and the delayed time is taken as empirical data as the time starting point of the next step. By adopting the control method, when the garbage is light and sparse (namely light load such as leaves), the pressure of the system rises rapidly, and high-pressure overflow is achieved quickly, and the high-pressure overflow time is long under the condition; when the garbage is heavy and dense (i.e. heavy load such as soil and stones), the pressure of the system rises slowly, and high-pressure overflow is difficult to achieve, even under the condition of not moving in place.
The invention is researched and proposed aiming at the defects of the prior art.
[ summary of the invention ]
The invention aims to solve the technical problem of providing a control method for reducing the overflow protection time of a hydraulic system, and overcomes the problems that the hydraulic system in the prior art has long light-load high-pressure overflow time and does not move in place under heavy load.
To solve the above technical problems, the present invention provides a control method for reducing an overflow protection time of a hydraulic system, the hydraulic system comprises an oil tank, a hydraulic pump connected with the oil tank, a main oil inlet channel connected with the hydraulic pump, a main oil return channel connected with the oil tank, an actuating oil cylinder, an electromagnetic valve for controlling the reversing of the actuating oil cylinder and a PLC (programmable logic controller) electric control unit, the actuating oil cylinder is connected between the main oil inlet path and the main oil return path through an electromagnetic valve, the electromagnetic valve comprises an electromagnet DT01 used for controlling the extension of a piston rod of the actuating oil cylinder and an electromagnet DT02 used for controlling the retraction of the piston rod of the actuating oil cylinder, an overflow valve which starts to overflow when the system pressure value reaches P1 is connected between the main oil inlet path and the main oil return path, the main oil inlet path is connected with a pressure relay for detecting the system pressure, and the control method comprises the following steps of:
s01: the PLC electric control unit sends out an instruction to electrify the electromagnet DT01, and a piston rod of the action oil cylinder begins to extend out;
s02: after time t1, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay, and when Pt is larger than a set value P2, the next step is executed;
s03: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s04: the PLC electric control unit sends out an instruction to enable the electromagnet DT01 to be uncharged, and a piston rod of the action oil cylinder stops extending;
s05: the PLC electric control unit sends out an instruction to electrify the electromagnet DT02, and a piston rod of the actuating oil cylinder begins to retract;
s06: after time t2, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay, and when Pt is larger than a set value P2, the next step is executed;
s07: the PLC electric control unit calculates the instantaneous change rate At of the system pressure value Pt, when the instantaneous change rate At is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s08: the PLC electronic control unit sends out an instruction to enable the electromagnet DT02 to be uncharged, and a piston rod of the actuating oil cylinder returns to the initial position and stops.
In the control method for reducing the overflow protection time of the hydraulic system, the P1 and the P2 satisfy the following conditions: 80% P1 ≤ P2 ≤ 95% P1. .
In the control method for reducing the overflow protection time of the hydraulic system, t1 satisfies the following conditions: t1 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t2 satisfies: t2 is more than or equal to 0.25 second and less than or equal to 0.35 second.
A control method for reducing the spill guard time for a hydraulic system as described above, a0 satisfies: a0 is more than or equal to 2.8(MPa/s) and less than or equal to 3.2 (MPa/s).
Based on the conception of the hydraulic system control method, the invention provides a control method of a hydraulic system of a compression mechanism of a rear-loading compression type garbage truck, the hydraulic system of the compression mechanism of the rear-loading compression type garbage truck comprises an oil tank, a hydraulic pump connected with the oil tank, a main oil inlet channel connected with the hydraulic pump, a main oil return channel connected with the oil tank, a scraper oil cylinder for controlling the opening or closing of a scraper, a slide plate oil cylinder for controlling the ascending or descending of a slide plate, an electromagnetic valve A for controlling the reversing of the scraper oil cylinder, an electromagnetic valve B for controlling the reversing of the slide plate oil cylinder and a PLC (programmable logic controller), the scraper oil cylinder is connected between the main oil inlet channel and the main oil return channel through the electromagnetic valve A, the electromagnetic valve A comprises an electromagnet DT1 for controlling the opening of the scraper and an electromagnet DT2 for controlling the closing of the scraper, the slide plate oil cylinder is connected, the electromagnetic valve B comprises an electromagnet DT3 for controlling the upward movement of the sliding plate and an electromagnet DT4 for controlling the downward movement of the sliding plate, an overflow valve which starts to overflow when the system pressure value reaches P1 is connected between the main oil inlet path and the main oil return path, the main oil inlet path is connected with a pressure relay for detecting the system pressure, and the control method of the compression mechanism comprises the following steps in sequence:
s01: the PLC electric control unit sends out an instruction to electrify the electromagnet DT1, and the scraper begins to open;
s02: after time t1, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay, and when Pt is larger than a set value P2, the next step is executed;
s03: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s04: the PLC electric control unit sends out an instruction to enable the electromagnet DT1 to be uncharged, and the scraper is stopped and kept after being stretched to the maximum position;
s05: the PLC electric control unit sends out an instruction to electrify the electromagnet DT4, and the sliding plate starts to descend;
s06: after time t2, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay, and when Pt is larger than a set value P2, the next step is executed;
s07: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s08: the PLC electric control unit sends out an instruction to enable the electromagnet DT4 to be uncharged, and the sliding plate stops and is kept after descending to the lowest position;
s09: the PLC electric control unit sends out an instruction to electrify the electromagnet DT2, and the scraper starts to scrape;
s10: after time t3, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay, and when Pt is larger than a set value P2, the next step is executed;
s11: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s12: the PLC electric control unit sends out an instruction to enable the electromagnet DT2 to be uncharged, and the scraper stops and keeps after being scraped to the initial position;
s13: the PLC electric control unit sends out an instruction to electrify the electromagnet DT3, and the sliding plate starts to move upwards;
s14: after time t4, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay, and when Pt is larger than a set value P2, the next step is executed;
s15: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s16: the PLC electric control unit sends out an instruction to enable the electromagnet DT3 to be uncharged, and the sliding plate stops after moving upwards to the initial position.
In the method for controlling the hydraulic system of the compression mechanism of the rear-loading compression-type garbage truck as described above, P1 and P2 satisfy: 80% P1 ≤ P2 ≤ 95% P1. .
In the method for controlling the hydraulic system of the compression mechanism of the rear-loading compression type garbage truck as described above, t1 satisfies the following conditions: t1 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t2 satisfies: t2 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t3 satisfies: t3 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t4 satisfies: t4 is more than or equal to 0.25 second and less than or equal to 0.35 second.
In the method for controlling the hydraulic system of the compression mechanism of the rear-loading compression type garbage truck as described above, a0 satisfies the following conditions: a0 is more than or equal to 2.8(MPa/s) and less than or equal to 3.2 (MPa/s).
Compared with the prior art, the invention has the following advantages:
1. in one working stroke (extending or retracting) of the hydraulic cylinder, when a system pressure value is larger than a set value P2, the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, namely the rising speed of the system pressure is slow (Kt is 0 during high-pressure overflow), the hydraulic cylinder is determined to move (extend or retract) to the maximum stroke position, the PLC electric control unit sends an instruction to enable the corresponding electromagnet to be uncharged and stop oil supply, and by adopting the control mode, no matter how the load changes, the piston rod can always move in place, the high-pressure overflow time is reduced, the useless power and the heat are reduced, the efficiency of the hydraulic system is improved, the oil temperature is reduced, the working cycle time is reduced, the working rhythm is improved, and the working efficiency is improved.
[ description of the drawings ]
The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings, in which:
fig. 1 is a hydraulic schematic diagram of a hydraulic system of embodiment 1 of the invention;
FIG. 2 is a schematic diagram of a hydraulic system of a rear-loading compression type garbage truck in embodiment 2 of the present invention;
fig. 3 is a comparison table of the action state of the hydraulic system of the rear-loading compression type garbage truck and the electrification state of the electromagnet in the embodiment 2 of the invention;
fig. 4 is a schematic diagram of a hydraulic system of a compression mechanism of a rear-loading compression type garbage truck according to embodiment 2 of the present invention;
fig. 5 is a comparison table of the hydraulic system operating state and the electromagnet energization state of the compression mechanism of the rear-loading compression type garbage truck in embodiment 2 of the present invention;
FIG. 6 is a graph of system pressure versus time for the hydraulic system of embodiment 2 of the present invention;
fig. 7 is a diagram of the system pressure versus time of a hydraulic system of a conventional rear-loading compression-type garbage truck.
[ detailed description ] embodiments
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Example 1:
as shown in fig. 1, a control method for reducing an overflow protection time of a hydraulic system according to this embodiment includes an oil tank 1, a hydraulic pump 2 connected to the oil tank 1, a main oil inlet 101 connected to the hydraulic pump 2, a main oil return 102 connected to the oil tank 1, an actuating cylinder 3, an electromagnetic valve 4 for controlling a direction change of the actuating cylinder 3, and a PLC electronic control unit, wherein the actuating cylinder 3 is connected between the main oil inlet 101 and the main oil return 102 through the electromagnetic valve 4, the electromagnetic valve 4 includes an electromagnet DT01 for controlling a piston rod of the actuating cylinder 3 to extend and an electromagnet DT02 for controlling a piston rod of the actuating cylinder 3 to retract, an overflow valve 5 for starting to overflow when a system pressure value reaches P1 is connected between the main oil inlet 101 and the main oil return 102, the main oil inlet 101 is connected to a pressure relay 6 for detecting a system pressure, the control method comprises the following steps of:
s01: the PLC electric control unit sends out an instruction to electrify the electromagnet DT01, and a piston rod of the actuating oil cylinder 3 begins to extend;
s02: after time t1, the PLC electric control unit starts to receive and process the system pressure value Pt detected by the pressure relay 6, and when Pt is larger than a set value P2, the next step is executed;
s03: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s04: the PLC electric control unit sends out an instruction to enable the electromagnet DT01 to be uncharged, and a piston rod of the actuating oil cylinder 3 stops extending;
s05: the PLC electric control unit sends out an instruction to electrify the electromagnet DT02, and the piston rod of the actuating oil cylinder 3 begins to retract;
s06: after time t2, the PLC electric control unit starts to receive and process the system pressure value Pt detected by the pressure relay 6, and when Pt is larger than a set value P2, the next step is executed;
s07: the PLC electric control unit calculates the instantaneous change rate At of the system pressure value Pt, and when the instantaneous change rate At is smaller than a set value A0, the next step is executed;
s08: the PLC electronic control unit sends out an instruction to enable the electromagnet DT02 to be uncharged, and the piston rod of the actuating oil cylinder 3 returns to the initial position and stops.
Among the above steps, steps S01 to S04 correspond to the process of "start-extend-stop" of the action cylinder 3, in which: in the time period of 0-t1, the corresponding process is the starting process, and the system pressure in the time period has larger impact and can exceed the set value P2, so in order to avoid interference, the PLC electronic control unit does not process the system pressure value Pt of the pressure relay in the time period of 0-t 1; when Pt is larger than a set value P2, the PLC electronic control unit calculates the instantaneous change rate Kt of the system pressure value Pt, and when the instantaneous change rate Kt is smaller than a set value A0, the PLC electronic control unit sends an instruction to enable the electromagnet DT01 to be uncharged, and the piston rod of the action oil cylinder 3 stops extending out; steps S05 to S08 correspond to the process of "start-retract-stop" of the actuating cylinder 3, and the control principle thereof is the same as that of the extending process, and further description thereof is omitted.
Compared with the prior art, in one working stroke (extending or retracting) of the hydraulic cylinder, when the system pressure value is larger than a set value P2, the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, namely the rising speed of the system pressure is slow (Kt is 0 during high-pressure overflow), the hydraulic cylinder is determined to move (extend or retract) to the maximum stroke position, the PLC electric control unit sends an instruction to enable the corresponding electromagnet to be uncharged, and oil supply is stopped.
In this embodiment, P2 satisfies: 80% P1-95% P2-1; t1 satisfies: t1 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t2 satisfies: t2 is more than or equal to 0.25 second and less than or equal to 0.35 second; a0 satisfies: a0 is more than or equal to 2.8(MPa/s) and less than or equal to 3.2 (MPa/s). t1, t2 and A0 can be obtained through experimental analysis, and the values adopted by different hydraulic systems are different.
In the embodiment, a universal control method of the hydraulic cylinder is provided.
Example 2:
as shown in fig. 2 to 6, the method for controlling a hydraulic system of a compression mechanism of a rear loading compression type garbage truck according to the present embodiment includes an oil tank 1, a hydraulic pump 2 connected to the oil tank 1, a main oil inlet 101 connected to the hydraulic pump 2, a main oil return 102 connected to the oil tank 1, a scraper cylinder 31 for controlling opening or closing of a scraper, a slide plate cylinder 32 for controlling ascending or descending of a slide plate, a solenoid valve a41 for controlling reversing of the scraper cylinder 31, a solenoid valve B42 for controlling reversing of the slide plate cylinder 32, and a PLC electric control unit, wherein the scraper cylinder 31 is connected between the main oil inlet 101 and the main oil return 102 through a solenoid valve a41, the solenoid valve a41 includes an electromagnet DT1 for controlling opening of the scraper and an electromagnet DT2 for controlling closing of the scraper, the slide plate cylinder 32 is connected between the main oil inlet 101 and the main oil return 102 through a solenoid valve B42, the electromagnetic valve B42 comprises an electromagnet DT3 for controlling the upward movement of the sliding plate and an electromagnet DT4 for controlling the downward movement of the sliding plate, an overflow valve 5 which starts to overflow when the system pressure value reaches P1 is connected between the main oil inlet channel 101 and the main oil return channel 102, the main oil inlet channel 101 is connected with a pressure relay 6 for detecting the system pressure, and the control method of the compression mechanism comprises the following steps in sequence:
s01: the PLC electric control unit sends out an instruction to electrify the electromagnet DT1, and the scraper begins to open;
s02: after time t1, the PLC electric control unit starts to receive and process the system pressure value Pt detected by the pressure relay 6, and when Pt is larger than a set value P2, the next step is executed;
s03: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s04: the PLC electric control unit sends out an instruction to enable the electromagnet DT1 to be uncharged, and the scraper is stopped and kept after being stretched to the maximum position;
s05: the PLC electric control unit sends out an instruction to electrify the electromagnet DT4, and the sliding plate starts to descend;
s06: after time t2, the PLC electric control unit starts to receive and process the system pressure value Pt detected by the pressure relay 6, and when Pt is larger than a set value P2, the next step is executed;
s07: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s08: the PLC electric control unit sends out an instruction to enable the electromagnet DT4 to be uncharged, and the sliding plate stops and is kept after descending to the lowest position;
s09: the PLC electric control unit sends out an instruction to electrify the electromagnet DT2, and the scraper starts to scrape;
s10: after time t3, the PLC electric control unit starts to receive and process the system pressure value Pt detected by the pressure relay 6, and when Pt is larger than a set value P2, the next step is executed;
s11: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s12: the PLC electric control unit sends out an instruction to enable the electromagnet DT2 to be uncharged, and the scraper stops and keeps after being scraped to the initial position;
s13: the PLC electric control unit sends out an instruction to electrify the electromagnet DT3, and the sliding plate starts to move upwards;
s14: after time t4, the PLC electric control unit starts to receive and process the system pressure value Pt detected by the pressure relay 6, and when Pt is larger than a set value P2, the next step is executed;
s15: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s16: the PLC electric control unit sends out an instruction to enable the electromagnet DT3 to be uncharged, and the sliding plate stops after moving upwards to the initial position.
Wherein, the steps S01 to S04 correspond to the process of driving the scraper to open by the scraper cylinder, and correspond to the section 0-T1 of the system pressure and time relation graph (P-T graph) in the attached figure 6; wherein: in the time period of 0-t1, the corresponding process is the starting process, and the system pressure in the time period has larger impact and can exceed the set value P2, so in order to avoid interference, the PLC electronic control unit does not process the system pressure value Pt of the pressure relay in the time period of 0-t 1; when Pt is larger than a set value P2 (corresponding to time G1), the PLC electronic control unit calculates the instantaneous change rate Kt of the system pressure value Pt, and when the instantaneous change rate Kt is smaller than a set value A0 (corresponding to time T1), the PLC electronic control unit sends an instruction to enable the electromagnet DT1 to be uncharged, and the scraper oil cylinder stops acting.
Steps S05 to S08, which correspond to the process of the slide plate cylinder driving the slide plate to move downwards and correspond to the sections T1-T2 of the system pressure and time relation graph (P-T graph) of the attached figure 6; wherein: the time period from T1 to T1+ T2 corresponds to the starting process, and the system pressure at the stage has larger impact and can exceed a set value P2, so in order to avoid interference, the PLC electronic control unit does not process the system pressure value Pt of the pressure relay in the time period from T1 to T1+ T2; when Pt is larger than a set value P2 (corresponding to time G2), the PLC electronic control unit calculates the instantaneous change rate Kt of the system pressure value Pt, and when the instantaneous change rate Kt is smaller than a set value A0 (corresponding to time T2), the PLC electronic control unit sends an instruction to enable the electromagnet DT4 to be uncharged, and the sliding plate oil cylinder stops acting.
Steps S09 to S12, which correspond to the scraping process of the scraper cylinder driving the scraper and correspond to the sections T2-T3 of the system pressure and time relation diagram (P-T diagram) of the attached figure 6; wherein: the time period from T2 to T2+ T3 corresponds to the starting process, and the system pressure at the stage has larger impact and can exceed a set value P2, so in order to avoid interference, the PLC electronic control unit does not process the system pressure value Pt of the pressure relay in the time period from T2 to T2+ T3; when Pt is larger than a set value P2 (corresponding to time G3), the PLC electronic control unit calculates the instantaneous change rate Kt of the system pressure value Pt, and when the instantaneous change rate Kt is smaller than a set value A0 (corresponding to time T3), the PLC electronic control unit sends an instruction to enable the electromagnet DT3 to be uncharged, and the scraper oil cylinder stops acting.
Steps S13 to S16, which correspond to the process of driving the slide plate to move upwards by the slide plate oil cylinder, and correspond to the sections T3-T4 of the system pressure and time relation graph (P-T graph) of the attached figure 6; wherein: the time period from T3 to T3+ T4 corresponds to the starting process, and the system pressure at the stage has larger impact and can exceed a set value P2, so in order to avoid interference, the PLC electronic control unit does not process the system pressure value Pt of the pressure relay in the time period from T3 to T3+ T4; when Pt is larger than a set value P2 (corresponding to time G4), the PLC electronic control unit calculates the instantaneous change rate Kt of the system pressure value Pt, and when the instantaneous change rate Kt is smaller than a set value A0 (corresponding to time T4), the PLC electronic control unit sends an instruction to enable the electromagnet DT3 to be uncharged, and the sliding plate oil cylinder stops acting.
In this embodiment, P2 satisfies: 80% P1-95% P2-1; t1 satisfies: t1 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t2 satisfies: t2 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t3 satisfies: t3 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t4 satisfies: t4 is more than or equal to 0.25 second and less than or equal to 0.35 second; a0 satisfies: a0 is more than or equal to 2.8(MPa/s) and less than or equal to 3.2 (MPa/s).
Comparing the description with figure 6 and the description with figure 7, it can be clearly found that: by adopting the control method, the high-pressure overflow time is shortened, the time of one action is shortened, the high-pressure overflow time is reduced, the useless power and the heat are reduced, the efficiency of a hydraulic system is improved, the oil temperature is reduced, the operation cycle time is shortened, the operation beat is improved, and the operation efficiency is improved.
Claims (2)
1. A control method of a hydraulic system of a compression mechanism of a rear-loading compression type garbage truck comprises an oil tank (1), a hydraulic pump (2) connected with the oil tank (1), a main oil inlet path (101) connected with the hydraulic pump (2), a main oil return path (102) connected with the oil tank (1), a scraper oil cylinder (31) for controlling opening or closing of a scraper, a sliding plate oil cylinder (32) for controlling ascending or descending of a sliding plate, an electromagnetic valve A (41) for controlling reversing of the scraper oil cylinder (31), an electromagnetic valve B (42) for controlling reversing of the sliding plate oil cylinder (32) and a PLC (programmable logic controller) unit, wherein the scraper oil cylinder (31) is connected between the main oil inlet path (101) and the main oil return path (102) through the electromagnetic valve A (41), the electromagnetic valve A (41) comprises an electromagnet DT1 for controlling opening of the scraper and an electromagnet DT2 for controlling closing of the scraper, the slide plate oil cylinder (32) is connected between a main oil inlet path (101) and a main oil return path (102) through an electromagnetic valve B (42), the electromagnetic valve B (42) comprises an electromagnet DT3 for controlling upward movement of the slide plate and an electromagnet DT4 for controlling downward movement of the slide plate, an overflow valve (5) which starts to overflow when a system pressure value reaches P1 is connected between the main oil inlet path (101) and the main oil return path (102), the main oil inlet path (101) is connected with a pressure relay (6) for detecting the system pressure, and the control method of the compression mechanism is characterized by comprising the following steps in sequence:
s01: the PLC electric control unit sends out an instruction to electrify the electromagnet DT1, and the scraper begins to open;
s02: after time t1, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay (6), and when Pt is larger than a set value P2, the next step is executed;
s03: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s04: the PLC electric control unit sends out an instruction to enable the electromagnet DT1 to be uncharged, and the scraper is stopped and kept after being stretched to the maximum position;
s05: the PLC electric control unit sends out an instruction to electrify the electromagnet DT4, and the sliding plate starts to descend;
s06: after time t2, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay (6), and when Pt is larger than a set value P2, the next step is executed;
s07: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s08: the PLC electric control unit sends out an instruction to enable the electromagnet DT4 to be uncharged, and the sliding plate stops and is kept after descending to the lowest position;
s09: the PLC electric control unit sends out an instruction to electrify the electromagnet DT2, and the scraper starts to scrape;
s10: after time t3, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay (6), and when Pt is larger than a set value P2, the next step is executed;
s11: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s12: the PLC electric control unit sends out an instruction to enable the electromagnet DT2 to be uncharged, and the scraper stops and keeps after being scraped to the initial position;
s13: the PLC electric control unit sends out an instruction to electrify the electromagnet DT3, and the sliding plate starts to move upwards;
s14: after time t4, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay (6), and when Pt is larger than a set value P2, the next step is executed;
s15: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s16: the PLC electric control unit sends out an instruction to enable the electromagnet DT3 to be uncharged, and the sliding plate stops after moving upwards to an initial position;
wherein: p1 and P2 satisfy: 80% P1-95% P2-1; t1 satisfies: t1 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t2 satisfies: t2 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t3 satisfies: t3 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t4 satisfies: t4 is more than or equal to 0.25 second and less than or equal to 0.35 second; a0 satisfies: a0 is more than or equal to 2.8(MPa/s) and less than or equal to 3.2 (MPa/s).
2. A control method for reducing overflow protection time of a hydraulic system comprises an oil tank (1), a hydraulic pump (2) connected with the oil tank (1), a main oil inlet path (101) connected with the hydraulic pump (2), a main oil return path (102) connected with the oil tank (1), an action oil cylinder (3), an electromagnetic valve (4) for controlling the reversing of the action oil cylinder (3) and a PLC (programmable logic controller) electric control unit, wherein the action oil cylinder (3) is connected between the main oil inlet path (101) and the main oil return path (102) through the electromagnetic valve (4), the electromagnetic valve (4) comprises an electromagnet DT01 for controlling the extension of a piston rod of the action oil cylinder (3) and an electromagnet DT02 for controlling the retraction of the piston rod of the action oil cylinder (3), an overflow valve (5) for starting to overflow when a system pressure value reaches P1 is connected between the main oil inlet path (101) and the main oil return path (102), the main oil inlet path (101) is connected with a pressure relay (6) for detecting system pressure, and the control method is characterized by comprising the following steps of:
s01: the PLC electric control unit sends out an instruction to electrify the electromagnet DT01, and a piston rod of the action oil cylinder (3) begins to extend out;
s02: after time t1, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay (6), and when Pt is larger than a set value P2, the next step is executed;
s03: the PLC electric control unit calculates the instantaneous change rate Kt of the system pressure value Pt, when the instantaneous change rate Kt is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s04: the PLC electric control unit sends out an instruction to enable the electromagnet DT01 to be uncharged, and a piston rod of the action oil cylinder (3) stops extending;
s05: the PLC electric control unit sends out an instruction to electrify the electromagnet DT02, and the piston rod of the actuating oil cylinder (3) begins to retract;
s06: after time t2, the PLC electric control unit starts to receive and process a system pressure value Pt detected by the pressure relay (6), and when Pt is larger than a set value P2, the next step is executed;
s07: the PLC electric control unit calculates the instantaneous change rate At of the system pressure value Pt, when the instantaneous change rate At is smaller than a set value A0, the rising speed of the system pressure is slow, the hydraulic cylinder is determined to move to the maximum stroke position, and the next step is executed;
s08: the PLC electric control unit sends out an instruction to enable the electromagnet DT02 to be uncharged, and a piston rod of the action oil cylinder (3) returns to an initial position and stops;
wherein: p1 and P2 satisfy: 80% P1-95% P2-1; t1 satisfies: t1 is more than or equal to 0.25 second and less than or equal to 0.35 second, and t2 satisfies: t2 is more than or equal to 0.25 second and less than or equal to 0.35 second; a0 satisfies: a0 is more than or equal to 2.8(MPa/s) and less than or equal to 3.2 (MPa/s).
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| CN202010745051.2A CN111852973B (en) | 2019-07-22 | 2019-07-22 | Control method of hydraulic system of compression mechanism of rear-mounted compression type garbage truck |
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| CN202010745051.2A CN111852973B (en) | 2019-07-22 | 2019-07-22 | Control method of hydraulic system of compression mechanism of rear-mounted compression type garbage truck |
| CN201910661653.7A CN110388342B (en) | 2019-07-22 | 2019-07-22 | Control method for reducing overflow protection time of hydraulic system |
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| CN110388342B (en) | 2020-09-04 |
| CN111852973B (en) | 2022-07-01 |
| CN110388342A (en) | 2019-10-29 |
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