JPH0158390B2 - - Google Patents

Description

[Detailed description of the invention] Technical field The present invention relates to an electromagnetic pressure control valve,
In particular, it relates to an electromagnetic pressure control valve using a solenoid coil excited by alternating current.

Prior Art Conventional electromagnetic pressure control valves use solenoid coils that are excited by direct current, but the force that attracts the armature of this direct current solenoid coil is easily affected by temperature changes, so pressure control The drawback was that the characteristics inevitably changed significantly. The attraction force of a DC solenoid assembly is determined by the current flowing through the solenoid coil, but since the resistance of the solenoid coil changes considerably depending on temperature, the attraction force of the solenoid coil is greatly affected by temperature. To avoid this, it was necessary to use a constant current power supply.

In addition, in pressure control valves using DC solenoid assemblies, hysteresis tends to be large when increasing and decreasing the pressure, and to reduce this, alternating current is superimposed on the direct current used to excite the solenoid coil. Countermeasures such as reducing the hysteresis had been taken, but these were still not sufficient due to the effects of residual magnetism, and the reality was that an electromagnetic pressure control valve with even lower hysteresis had been awaited.

Purpose of the Invention In view of the above circumstances, the present invention has been made with the object of providing an electromagnetic pressure control valve that is less susceptible to temperature changes and has less hysteresis.

Structure of the Invention In order to achieve this object, an electromagnetic pressure control valve according to the first invention includes (a) an AC power supply device with variable voltage or current, and (b) a solenoid coil connected to the AC power supply device. (c) an armature movably disposed inside the solenoid coil; (d) a spool having a land and capable of abutting the armature directly or indirectly through a rigid member at a first end; (e) having a pressure port and a drain port, the spool being movable in the axial direction, and
(f) a housing in which the land accommodates the pressure port and the drain port in a state where communication with the pressure port and the drain port is cut off; (g) a notch formed to increase the throttling effect when moving toward the second end opposite to the first end; and (g) feedback of a force corresponding to the pressure of the pressure port to the second end of the spool. and a feedback mechanism.

Moreover, the electromagnetic pressure control valve according to the second invention is configured to include a vibration absorbing member in addition to the above-mentioned components. This vibration absorbing member has an elastic deformability smaller than the axial dimension of the notch, and when the spool and the armature are in direct contact with each other, there is a vibration absorbing member between them, or between the two with another rigid member interposed between them. When the rigid member is brought into contact with the armature or the spool, it is interposed between the rigid member and the armature or spool.

Functions and Effects of the Invention When alternating current is used to excite the solenoid coil as described above, the proportion of resistance in the impedance of the solenoid coil becomes significantly small, so the armature attraction force of the solenoid coil due to temperature changes decreases. Changes are also significantly reduced, resulting in an electromagnetic pressure control valve that is less susceptible to temperature changes.

In addition, DC solenoid assemblies have large hysteresis due to the influence of residual magnetism, but when using AC solenoid assemblies, residual magnetism is small, and hysteresis due to frictional resistance is also reduced because vibrations occur in the armature and spool. , an electromagnetic pressure control valve with very small hysteresis can be obtained. However, AC solenoid assemblies have not been considered in the past because they are accompanied by large vibrations in the armature, and the state of vibration changes markedly depending on the position of the armature, especially when the stroke range is widened. In this respect, in the first invention, the armature is brought into direct contact with the spool, and when brought into contact indirectly, the armature is brought into contact through a rigid member instead of through an elastic member such as a spring as in the conventional method. As a result, only a small stroke of the armature is required. Further, when the armature and the valve element (spool) are brought into rigid contact as described above, the vibration of the armature is transmitted to the valve element, causing the valve element to vibrate. Therefore, if a seated valve is used, if the valve element vibrates, the area of the orifice formed by the seat and valve element will change greatly due to the vibration, and the controlled pressure will also fluctuate greatly, making it difficult to stabilize. pressure control cannot be obtained. However, in the first invention, since the spool is used as the valve and the notch formed in the land is used, stable pressure control characteristics can be obtained without the vibration of the spool causing a large change in the aperture area. It can be done.

Further, if a vibration absorbing member is interposed between the armature and the spool as in the second invention, the vibration of the spool can be reduced to an appropriate level that can reduce friction but does not adversely affect pressure control. Can be done. Furthermore, if the elastic deformability of the vibration absorbing member is made smaller than the axial dimension of the notch, the stroke of the armature will increase somewhat due to the elastic deformation of the vibration absorbing member. The state of vibration does not change significantly.

Embodiments Hereinafter, two or three embodiments of the present invention will be described in detail based on the drawings.

In FIG. 1, reference numeral 10 denotes a housing which is the main body of the hydraulic control valve.For convenience of manufacture, it is divided into two parts, but after assembly, it functions as an integrated housing. This housing 10 has a pressure port 1
2 and a drain port 14 are provided, the pressure port 12 being connected to a pump circuit 20 by a line 18 with a restriction 16, while the drain port 14 is connected to a tank 24 by a line 22. It is connected. Therefore, from tank 24 to pump 2
A part of the hydraulic oil pumped up by 6 is transferred to pipe 1.
8 to the pressure port 12, and is returned to the tank 24 from the drain port 14 via the conduit 22.

The flow path from this pressure port 12 to the drain port 14 is constricted by a spool 28. Spool 28 is housing 1
It is fitted into a spool hole formed in the spool hole substantially oil-tightly and slidably in the axial direction, and is provided with a land 30 at one end. The land 30 is formed to cut off communication between the pressure port 12 and the drain port 14, and the land 30 is formed with a notch 32 as shown enlarged in FIGS. 2 and 3. The hydraulic oil led to the pressure port 12 is spouted from an annular groove 34 of the spool 28 through a notch 32 into a low pressure chamber 36. Moreover,
As is clear from FIG. 2, the notch 32 is formed to become deeper toward the end of the land 30. Therefore, as the spool 28 moves to the right in FIG.
This will increase the throttling effect on the hydraulic oil flowing to.

An armature tube 38 is fixed to the end of the housing 10 on the low pressure chamber 36 side by screwing, and an armature 40 is disposed within the armature tube 38 so as to be movable in the axial direction. A working protrusion 42 protruding from one end surface of the armature 40 is adapted to come into contact with one end of the spool 28. Further, a solenoid coil 44 is fixed to the outside of the armature tube 38, and this solenoid coil 44 is connected to an AC power source 46 whose voltage (or current) is variable. Thus, when solenoid coil 44 is supplied with alternating current, armature 40 is attracted to the central position of solenoid coil 44 and exerts a force on spool 28 in the positive direction, i.e., to the right in FIG. It happens. This rightward force increases or decreases as the voltage applied to the solenoid coil 44 by the AC power source 46 increases or decreases.

A force in the opposite direction, ie, to the left, is applied to the spool 28 by the feedback mechanism 50, and at a position where this force and the rightward force by the armature 40 are balanced, the spool 28
has been stopped. The feedback mechanism 50 includes a backup plunger 5 that operates in response to pressure from a pressure port 12 guided by a feedback passage 52 formed in the housing 10.
It is equipped with 4. This backup plunger 5
4 is fixed to a piston 58 that is fitted in an oil-tight and slidable manner within an oil chamber 56 formed in the housing 10. This piston 58 is provided facing the end of the spool 28 opposite to the side that contacts the armature 40, and is supported by a spring 60 with a large elastic force disposed between the piston 58 and the housing 10. It is urged in the direction away from the spool 28. Also, piston 5
8 and another piston 62 fixed to the end of the spool 28 is a spring 6 with a small elastic force.
4 is provided, and the elastic force of this spring 64 is applied to the spool 28 via the piston 62.

By disposing the pistons 58 and 62 in the oil chamber 56 as described above, the oil chamber 56 is divided into a first chamber 66, a second chamber 68, and a third chamber 70. One room 66 has drain port 7
2 to the tank 24, and the third chamber 70
is communicated with the low pressure chamber 36 through a communication passage 74. Further, the second chamber 68 is communicated with the third chamber 70 by a communication passage 76 that is formed between the outer circumferential surface of the piston 62 and the inner circumferential surface of the oil chamber 56 and has a throttle effect.

When a constant voltage is applied by the AC power supply 46 to the solenoid coil 44 of the hydraulic control valve configured as described above, and a constant hydraulic pressure is introduced from the pump circuit 20 to the pressure port 12, the spool 28 is stopped at the position shown in FIG. That is, the armature 40 applies a rightward force to the spool 28 based on the attraction force of the solenoid coil 44, and the spring 64 applies a rightward force to the spool 28.
The leftward force applied to is balanced.

When the voltage of the AC power supply 46 is increased from this state, the rightward force applied by the armature 40 to the spool 28 increases, causing the spool 28 to
Move it to the right against the elastic force of step 4. As a result, the flow path area in the notch 32 is reduced and the throttling effect is enhanced, so that the oil pressure in the pressure port 12 increases, and this is transmitted to the plunger 54 through the feedback passage 52. As a result, the plunger 54 moves the piston 58 forward against the elastic force of the spring 60, thereby compressing the spring 64 and increasing the leftward force on the spool 28. That is, as the pressure in the pressure port 12 increases, the piston 58 advances, and this advancement increases the elastic force of the spring 64, which ultimately increases the amount of pressure increase in the pressure port 12 and the amount applied to the spool 28. It is proportional to the amount of increase in the leftward force. Then, the spool 28 stops when this leftward force is balanced with the above-mentioned rightward force by the armature 40, so the pressure in the pressure port 12 is reduced by the armature 4.
By changing the attraction force of 0, that is, the voltage of the AC power source 46, it can be changed arbitrarily. The hydraulic pressure from this pressure port 12 can be taken out and used for various purposes.

Note that the voltage of the AC power supply 46 is suddenly increased,
If the rightward force applied to the spool 28 by the armature 40 suddenly increases,
Before the piston 58 moves forward and increases the elastic force of the spring 64, the spool 28 moves to the right, and the throttling effect in the notch 32 becomes too high, resulting in a so-called overshoot in which the pressure in the pressure port 12 becomes temporarily excessive. However, this hydraulic control valve prevents this overshoot from occurring. That is, the piston 58, which moves forward as the oil pressure in the pressure port 12 increases, transfers the hydraulic oil in the second chamber 68 to the third chamber 70 and the communication passage 7.
4 to the drain port 14, and since the second chamber 68 and the third chamber 70 are only communicated through a narrow communication passage 76, the hydraulic pressure in the pressure port 12 is When the piston 58 rapidly moves forward, a throttling effect is applied to the flow of hydraulic oil from the second chamber 68 to the third chamber 70, and the oil pressure in the second chamber 68 increases. applies a leftward force to the spool 28 via the piston 62, and the magnitude of this force increases as the forward speed of the piston 58 increases, that is, as the oil pressure in the pressure port 12 increases rapidly. against the rightward force of
This prevents the spool 28 from moving suddenly to the right.

As is clear from the above explanation, in this hydraulic control valve, hydraulic control is performed by moving the armature 40 by the same amount as the spool 28, and since the amount of movement of the spool 28 is small, the hydraulic pressure is The stroke of the armature 40 for control purposes is small. For example, the length of the notch 32 formed in the spool 28 of this embodiment is 1 mm, and a stroke of the armature 40 of less than that length allows hydraulic control over a wide range. Therefore, it is less affected by changes in the suction force due to changes in the position of the armature 40 with respect to the solenoid coil 44, and hydraulic control characteristics that can withstand practical use can be obtained with a simple electric circuit. For example, it is sufficient to control the voltage and current of a 50- or 60-cycle commercial power supply using a resistor or thyristor.

Moreover, this hydraulic control valve is extremely unlikely to be affected by temperature changes in the solenoid coil. This is clear from FIGS. 4 and 5. Figure 4 is a graph showing the change in suction force when the solenoid coil 44 used in this example is in a cooling state of 30°C and when it is in a saturated temperature state of 150°C. This is a graph showing the change in attraction force between the cooling state and the saturated temperature state when the solenoid coil is excited with direct current. Comparing the two, it is clear that this hydraulic control valve is a hydraulic control valve using a conventional direct current solenoid coil. It can be seen how much less affected by temperature it is compared to .

Moreover, in this hydraulic control valve, the hysteresis between increasing and decreasing the hydraulic pressure is so small that it cannot be measured with a normal meter.

Although the configuration, operation, and effects of one embodiment of the present invention have been described in detail above, the present invention is not limited to this embodiment and can be implemented in various ways.

An example is shown in FIG. In this embodiment, pressure port 1 in the embodiment shown in FIG.
In addition to 2, another pressure port 77 is provided,
The hydraulic pressure of the pump circuit 20 is introduced to this pressure port 77 through a conduit 18. The spool 28 has a land 30 and a notch 3.
2, a land 78 and a notch 79 are provided. The hydraulic fluid led to the pressure port 77 flows through the notch 79 to the pressure port 12, and further flows from the pressure port 12 through the notch 32 to the low pressure chamber 36, and the pump circuit 2
0 oil pressure is reduced by the throttling effect of the notch 79 and guided to the pressure port 12.
2 is further controlled by the throttling effect of the notch 32. When the spool 28 is moved in the forward direction, the notch 79
By increasing the flow passage area of the notch 32 and decreasing the flow passage area of the notch 32, or by blocking the flow, the hydraulic pressure of the pressure port 12 is increased, and when the flow is moved in the opposite direction, the flow at the notch 32 is increased. The hydraulic pressure of the pressure port 12 is decreased by increasing the passage area and decreasing the passage area in the notch 79 or cutting off the flow. The hydraulic pressure of the pressure port 12 controlled in this manner is taken out to the outside and used for various purposes. Other parts are the same as the embodiment shown in Fig. 1, so corresponding parts are given the same reference numerals and detailed explanations are omitted. However, this embodiment has a drain port for pressure control. There is an advantage that only a small amount of hydraulic oil is required to be returned from 14 to tank 24.

Another embodiment of the invention is shown in FIGS. 7 and 8. The one shown in FIG. 7 corresponds to the embodiment shown in FIG. 1 in which the backup plunger 54 is brought into direct contact with the spool 28, and a variable throttle valve is installed in the middle of the feedback passage 52 to prevent vibration of the spool 28. 80 are provided. Also, the 8th
In the pressure control valve shown in the figure, a piston 82 is fixed to the rear end of the plunger 54, and a first chamber 83 and a third chamber 84 on both sides of the piston 82 are communicated with each other through a communication passage 86. A variable throttle valve 88 is provided in the middle of the passage 86.
The piston 82, communication passage 86, and variable throttle valve 88 are also provided to prevent vibration of the spool 28. Since other parts are the same as those in the embodiment shown in FIG. 1, corresponding parts are given the same reference numerals and detailed explanations will be omitted.

In the above two embodiments, the operating force of the backup plunger 54 is directly transmitted to the spool 28, and since the diameter of the backup plunger 54 cannot be made as small as desired due to processing constraints, control is required. When the oil pressure is high, there is a disadvantage that the solenoid coil 44 and the armature 40 need to be enlarged to resist the operating force of the back-up plunger 54, but since the feedback mechanism can be simplified, it is relatively simple. This is suitable as a hydraulic control valve used in a low pressure range.

Yet another embodiment of the invention is shown in FIG. In this embodiment, a vibration absorbing member 90 is added to the embodiment shown in FIG. That is, a cup-shaped holding member 92 is fitted to the tip of the working projection 42 of the armature 40, and a vibration absorbing member 90 is disposed between the bottom of this holding member 92 and the tip surface of the working projection 42. . Therefore, armature 4
0 and the spool 28 come into contact with each other via the vibration absorbing member 90. The vibration absorbing member 90 is made of rubber and can be elastically deformed, but its elastic deformability, that is, the amount by which it can be elastically deformed without being damaged or plastically deformed, is smaller than the dimension of the notch 32 in the spool axial direction. ing.

The vibration absorbing member 90 absorbs the vibration of the armature 40 and acts to reduce the amount of vibration transmitted to the spool 28. Therefore, the spool 28 receives an amount of vibration suitable for reducing the frictional force with the housing 10. Vibrations of the spool 28 that would otherwise be transmitted and adversely affect pressure control are prevented. Although the vibration absorbing member 90 is made of rubber in this embodiment, it is also possible to use an elastic member made of metal.

In addition, although all of the above embodiments are hydraulic control valves, it is also possible to apply the present invention to pressure control valves that control the pressure of gases such as air as well as liquids other than oil. Although not illustrated, it is of course possible to implement the present invention in various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing a hydraulic control valve according to an embodiment of the present invention. Figure 2 is an enlarged front view (partially cut away) of the spool used in the above hydraulic control valve.
FIG. 3 is a plan view showing the main parts of the spool. FIGS. 4 and 5 are graphs showing changes in attractive force based on temperature changes of the solenoid coil when the same solenoid coil is excited with alternating current and when excited with direct current. 6 to 9 are front sectional views showing other embodiments of the present invention, respectively. 10: Housing, 12: Pressure port, 14:
Drain port, 16: Throttle, 20: Pump circuit,
28: Spool, 30,78: Land, 32,7
9: Notch, 38: Armature tube, 4
0: Armature, 44: Solenoid coil, 4
6: AC power supply, 50: Feedback mechanism, 5
2: Feedback passage, 54: Backup plunger, 58, 62: Piston, 60, 64:
Spring, 74, 76: Communication path, 77: Pressure extraction port.

Claims (1)

[Claims] 1. An AC power supply device with variable voltage or current, a solenoid coil connected to the AC power supply device, an armature movably disposed inside the solenoid coil, and a land, A spool that can come into contact with the armature directly or indirectly through a rigid member at a first end, and a pressure port and a drain port, the spool being movable in the axial direction, and the land being connected to the pressure port. a housing housing the spool in a state in which communication with the drain port is cut off, and a land of the spool that allows the pressure port and the drain port to communicate with each other while giving a throttling effect; a notch formed to increase the throttling effect when moving toward the second end, and a feedback mechanism that feeds back a force corresponding to the pressure of the pressure port to the second end of the spool, the solenoid coil An electromagnetic pressure control valve characterized in that the pressure in the pressure port can be changed by changing the power supplied to the pressure control valve. 2. An AC power supply device with variable voltage or current, a solenoid coil connected to the AC power supply device, an armature movably disposed inside the solenoid coil, and a land, the armature being connected to the armature at a first end. a spool facing the spool; a housing having a pressure port and a drain port and accommodating the spool so as to be movable in the axial direction and with the land cutting off communication between the pressure port and the drain port; The land is formed so that the pressure port and the drain port communicate with each other while giving a throttling effect, and the throttling effect increases when the spool moves toward a second end opposite to the first end. a notch having an elastic deformation capacity smaller than the axial dimension of the notch and interposed between the first end of the spool and the armature, alone or together with a rigid member, and from the armature to the spool; A vibration absorbing member that reduces transmitted vibration; and a feedback mechanism that feeds back a force corresponding to the pressure of the pressure port to the second end of the spool, and the pressure can be adjusted by changing the power supplied to the solenoid coil. An electromagnetic pressure control valve characterized by being able to change port pressure.