JPH0140799Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to the improvement of a steering system for a ship, particularly a two-loop type steering system in which a rudder control mechanism and a rudder are mechanically coupled in a cascade.

<Conventional example> The block diagram shown in Fig. 1 is an example of a curved configuration of a conventional two-loop steering system. The control mechanism, the right part of which drives the rudder, is a rudder machine consisting of a hydraulic servo mechanism that also has its own feedback function, and both are connected in a cascade by a mechanical lever mechanism.

On the rudder control mechanism side A, block 1 is a control unit that receives an input signal e (the difference between the azimuth signal measured by the gyro compass and the set signal), and this signal is subjected to correction calculations based on weather and other factors by block 11. Ru. The output e′〓 is led to the input of the differential amplifier 12, where it is compared and amplified with the signal e〓 related to the displacement of the output shaft 4 of the servo cylinder 3, and the deviation signal e _d is led to the switch circuit 13. , is converted into an on/off signal for driving the power unit 2 according to the polarity of the deviation. This power unit 2 controls the direction and flow rate of the fluid in the fluid passages 31 and 32 to the servo cylinder 3, and is usually realized by a four-way electromagnetic switching valve driven by on/off control of the solenoid 21. The movement of the output shaft 4 of the servo cylinder 3 is converted into an electric signal e by a displacement/electrical signal converter 5 and fed back to the input of the differential amplifier 12. This output shaft 4 is further linked to an input lever 61 of a proportional control type fluid pressure pump 6 constituting the rudder, and transmits the output from the rudder control mechanism A to the rudder B. 7 is a rudder driven by the fluid pressure pump 6, and the rotation angle of the output shaft is fed back to the input lever 61 of the fluid pressure pump 6 via a lever 62.

That is, the two-loop system has a configuration in which a system having two feedback loops is connected in series in a cascade, and the rudder control mechanism A side and the rudder control mechanism B side are divided into two with C as a boundary. Therefore, (1) Each system can be adjusted and maintenance is easy.

(2) The scope of responsibility of the rudder control mechanism A and rudder B in each system is clear, making shipbuilding design easy.
For these reasons, it is mechanically a little more complicated than the so-called single-loop system, but it is a system that is often used in conventional ships.

In such a two-loop steering system, the fluid pressure pump 6 that drives the rudder 7 uses a proportional control type as described above, so the displacement of the output shaft 4 of the servo cylinder 3 and the feedback lever are controlled as shown in FIG. In the range where the difference in displacement of 62, that is, the deviation input, is less than α, the fluid output speed of the fluid pressure pump has a characteristic that it is proportional to the input, but the output speed of the servo cylinder 3 changes in an on-off manner as shown in Figure 3. The amplifier 12 is switched to improve course keeping accuracy.
When the gain is increased, hunting will occur in the system unless a dead zone is provided as shown in the figure. This dead zone needs to be approximately 0.5° in both the surface rudder direction and the steering direction, and a total range of approximately 1°.

In recent years, there has been an increasing trend toward energy-saving ships, and steering systems that minimize the dead zone have been proposed to address even the small meandering range described above. One such trend is the so-called single-loop system. The feature is that the displacement of the machine is directly fed back to the input of the amplifier.

However, when using the single-loop system, when manually controlling the proportional control fluid pressure pump 6 for controlling the rudder in an emergency, the output speed is relatively slow, so it is easy to overshoot, and the rudder and control mechanism Since the two loops form one feedback loop, maintenance is more difficult than with the two-loop system, and it is necessary to install the pump drive control unit, which is made up of electronic components, in the rudder cabin, which has a poor environment. There are other problems.

On the other hand, another approach is to minimize the dead zone by taking advantage of the two-loop system explained in Fig. There are attempts to add control properties. That is, input e _d
When the deviation is less than a certain value, the fluid supply speed to the servo cylinder 3 is made proportional to the value of _ed , and when the deviation is small, the steering gear control mechanism A side forms a proportional control loop. be. As a specific means for realizing proportional control of a servo cylinder, a device using a proportional control valve called a servo valve is known. Various servo valve structures have been proposed, but they are relatively complex structures that incorporate amplification means using nozzles and flappers in terms of curved shape, and have the following drawbacks.

(1) Design of hysteresis, resolution, zero drift, guide valve overlap, underlap, etc.
Compensation is complicated.

(2) The structure is complex and requires precision design;
It's expensive.

(3) The nozzle/flap mechanism is susceptible to contamination of the working fluid and is prone to failure.

(4) In order to perform emergency steering in the event of a failure, it is necessary to install an electromagnetic switching valve that bypasses the servo valve and manually controls the on/off of the servo cylinder, making the overall system structure complex.

<Objective of the present invention> The present invention aims to eliminate the drawbacks of the two-loop system as described above, and to realize a steering device that is additional, simple in structure, inexpensive, and highly reliable.

<Configuration of the present invention> The feature of the present invention is that it uses an electromagnetic proportional valve, which has become inexpensive and highly reliable in recent years, and combines it with a conventional on/off controlled four-way electromagnetic switching valve to reduce deviation. It is characterized by proportionally controlling the fluid supply flow rate to the servo cylinder within a certain range.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram showing the basic configuration of the device of the present invention, and the same elements as those in the conventional configuration shown in FIG. The first difference from Fig. 1 is that there is an electromagnetic proportional valve 2 in the power unit 2.
2 is provided and combined with the 4-way electromagnetic switching valve 21,
A second difference is that a proportional control means 14 is provided in the control unit 1 for supplying a current i _p (or a current _p inversely proportional) to the electromagnetic proportional valve 22.

FIG. 5 shows an example of a specific configuration inside the power unit 2, in which electromagnetic proportional valves 22 are combined in a bleed-off method, and in this case, the solenoid 22a of the electromagnetic proportional valve has a deviation _signal An inversely proportional signal _p is supplied. The fluid 9 in the oil tank 8 is supplied by a pump 10 to a four-way electromagnetic switching valve 21 and an electromagnetic proportional valve 22 forming a bleed-off circuit.
It is supplied to the servo cylinder 3 via both of these. 91 is the pump port, 92 is the tank port,
Reference numerals 93 indicate bleed-off channels. In this configuration, the electromagnetic proportional valve 22 is controlled in inverse proportion to the deviation, so when the deviation is large, the bleed-off flow path 9
3 is small, and therefore the flow velocity in the flow paths 31 and 32 to the servo cylinder 3 is high. Conversely, when the deviation e _d becomes small, the flow rate in the bleed-off flow path 93 becomes large, and the flow rate of the fluid to the servo cylinder 3 increases. becomes smaller. Such proportional control of the flow velocity to the servo cylinder 3 occurs within a certain range of deviation e _d ,
On/off control is performed for deviation signals exceeding a certain value. The four-way electromagnetic switching valve 21 has a pair of solenoids 21a and 21b, and is selectively driven on and off by drive voltages Vp and Vs selectively supplied according to the polarity of the deviation signal _ed .

FIG. 6 shows an example of the configuration inside the control unit 1, in which the switch circuit 13 receives the deviation signal.
A switch 132 that switches the power supply voltage +V according to the polarity of e _d , and a comparator 13 that drives this switch.
1, and selectively supplies driving voltages Vp and Vs to the solenoids 21a and 21b of the four-way electromagnetic switching valve 21. Eh is a variable voltage source that provides the comparator threshold and sets the dead zone of the system. Vp,
The interlocking switches 151 and 152 inserted in the middle of the supply circuit of
This is an automatic/manual changeover switch for manually controlling the power supply voltage +V when switched to manual side M.
are supplied to solenoids 21a and 22b, respectively.
141 is an inverter that inverts the polarity of the deviation signal _ed , and 142 is an adder, in which the output _d of 141 and signals for various adjustments such as zero point and dither given from block 143 are added. The output of this adder 142 is converted by a voltage/current converter 144 into a current _p related to the reciprocal of the deviation, 151, 15
The electric power is supplied to the solenoid 22a of the electromagnetic proportional valve 22 in the power unit 2 through an automatic/manual changeover switch 153 that operates in conjunction with the power unit 2.

Next, the operating characteristics will be explained with reference to FIG. In this example, the range of proportional control for deviation is
In the range where the deviation is set to 5 degrees and the deviation is extremely small, overall controllability is improved by using on/off characteristics with an extremely small dead zone rather than complete proportional control.

Figure A shows the steering speed, that is, the fluid flow velocity characteristics to the servo cylinder 3. If the deviation is 5° or more, the maximum speed is 7°/22 seconds, and if the deviation is 5° or less, this speed is proportional to the deviation. and become smaller,
In the vicinity where the deviation is very close to zero, a small flow rate on/off characteristic with a dead zone of 0.1° each for surface rudder and steering, and a total of 0.2° is provided to prevent deterioration of controllability due to complete proportional control.

Figure B shows the flow rate of fluid that bleeds the electromagnetic proportional valve 22. The maximum discharge flow rate from pump 10 is 5
/min, and the flow rate at which the electromagnetic proportional valve 22 bleeds off is selected to be a maximum of 4.5/min and a minimum of 2/min, and in the range where the deviation is 5° or more, the bleed-off flow rate is the minimum value of 2/min, and the deviation is zero. Maximum 4.5/min when
When the deviation is in the range of 0° to 5°, the bleed-off flow rate changes in inverse proportion to the span deviation of 2.5/min. Therefore, even when the deviation is zero, the bleed-off flow rate is 4.5/min, and 0.5/min is supplied to the 4-way electromagnetic switching valve side 21, making it possible to perform on/off control for the servo cylinder 3 within a range where the deviation is extremely small. It's getting old. Figure C shows the operating characteristics of the four-way electromagnetic switching valve 21 showing an enlarged view of the extremely small deviation range, and the dead band width θ is approximately
It is less than 0.2°, and the dead zone can be significantly reduced to 1/5 of that of conventional on/off control.

FIG. 8 shows an example in which the electromagnetic proportional valve 22 is inserted in series into the pump port 91 of the four-way electromagnetic switching valve 21. The operation of 22 in this case is opposite to that in FIG. 5, and is driven by a current i _p proportional to the deviation. Therefore, the inverter 14 in the control unit 1
1 becomes unnecessary. Since the proportional control operation for the servo cylinder 3 is almost the same as the operation explained in FIGS. 5 to 7, the explanation will be omitted. In this case, the same effect can be obtained even if the electromagnetic proportional valve 22 is provided on the tank port 92 side.

<Effects> As explained above, the present invention can be realized by combining a conventionally commonly used four-way electromagnetic switching valve with an electromagnetic proportional valve, so the following effects can be expected.

(1) The solenoid proportional valve has an extremely simple structure.
Even when combined with a 4-way electromagnetic switching valve, no complicated adjustment or compensation is required.

(2) Compared to servo valves, the price is extremely low and the economical effect is high.

(3) Since the proportional operation part has a structure that does not allow fluid contamination, there are fewer failures and the reliability of the entire system is improved. Generally, the failure mode of a proportional solenoid valve is in the direction of blocking the flow path, so when used in the bleed-off type as shown in Figure 5, even if the proportional solenoid valve has an electrical failure due to wire breakage, the As explained in Figure 6, conventional automatic steering is possible by simply returning the dead zone setting to the on/off type, and it is also possible to manually operate the 4-way electromagnetic switching valve to drive the servo cylinder. be. In the case of series insertion as shown in FIG. 8, a step is required to open the flow path by operating the electromagnetic proportional valve.

(4) When modifying an existing two-loop system with an on-off type servo cylinder, the electromagnetic proportional valve and its drive circuit are additional, and it can be modified to a proportional control type steering device with extremely simple construction.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of a conventional steering device, Figs. 2 and 3 are explanatory diagrams of its operation, Fig. 4 is a block diagram showing an embodiment of the present invention, and Figs. 5 and 6. 7 is a diagram for explaining its operation, and FIG. 8 is a diagram showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Control unit, 2... Power unit, 3... Servo cylinder, 6... Fluid pressure pump, 7... Rudder, 21... 4-way electromagnetic switching valve, 2
2...Solenoid proportional valve.

Claims (1)

[Scope of utility model registration request] A deviation detection means for detecting and amplifying a deviation between an input signal related to a difference between a measured azimuth signal and a set azimuth signal and an electric signal corresponding to a mechanical output of a hydraulic servo mechanism for driving a rudder gear; and this deviation detection means. a power unit that receives the output of the fluid pressure servo mechanism and controls the fluid supply flow rate to the fluid pressure servo mechanism; and a rudder machine that receives the mechanical output of the fluid pressure servo mechanism and controls the position of the rudder in proportion to this output. In the loop type steering device, means for switching the direction of fluid supply to the fluid pressure servo mechanism according to the polarity of the deviation, and means for switching the direction of fluid supply to the fluid pressure servo mechanism in response to the deviation within a range of a certain value or less. A steering device comprising means for proportionally controlling a fluid supply flow rate.