JPH06235406A - Cooling mechanism for liquid pressure cylinder - Google Patents

Abstract

PURPOSE:To provide a cooling mechanism for a liquid pressure cylinder, of which constitution is simple to prevent enlarging of a device and which can perform required cooling without providing an exclusive cooling means such as a water cooling jacket while reducing a cost. CONSTITUTION:Two ports 20, 22 are provided in one pressure chamber 8 of a cylinder main body 6, and a liquid pressure change-over valve 10 is provided which changes over leading of liquid fed from a liquid feed source 12 to either the pressure chamber 8 on the rod side or a pressure chamber 9 on the head side. A bypass liquid passage 23 is provided branching from a liquid passage 9a extending from the liquid pressure change over valve 10 to the pressure chamber 9 on the head side, and extending to the pressure chamber 9 on the rod side, and a two-position change-over valve 24 for changing over to either of two positions of shut-off and opening is interposed in the bypass liquid passage 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling mechanism for a hydraulic cylinder.

[0002]

2. Description of the Related Art A hydraulic cylinder for driving a mechanism in a high temperature state is prevented from being damaged due to heat, resulting in damage to a packing of a sliding portion of a piston rod or deterioration of hydraulic oil in a hydraulic chamber. Therefore, various measures have been taken to suppress the influence of conduction heat and radiant heat received from the high temperature portion of the mechanism as small as possible.

FIG. 4 shows an example of a hydraulic cylinder devised for cooling. A hydraulic cylinder 1 shown in the figure is provided as a means for driving a needle nozzle 2 of a resin molding machine, and the needle nozzle 2 uses a molten plastic resin injection mechanism (not shown) for injecting a molten resin into a molding machine at a subsequent stage. It is used to supply or stop the supply to the mold cavity (not shown).

An inflow port 3a is formed on the side of the nozzle body 3, and the molten resin entering from the inflow port 3a communicates with the lateral hole 3b extending in the nozzle body 3 in the radial direction and the lateral hole 3b. It is adapted to be supplied from an outlet 3d formed at the tip of the nozzle body 3 via a vertical hole 3c formed along the central axis of the nozzle body 3. The first and second heaters 4 and 4 are attached to the outer periphery of the nozzle body 3 to keep the resin in a molten state.

The proximal end side of the needle pin 5 which opens and closes the outlet 3d of the nozzle body 3 projects to the outside of the nozzle body 3 through the vertical hole 3c, and the hydraulic cylinder 1 is attached to the proximal end thereof. Has been. Then, the needle pin 5 which is integral with or connected to the piston rod is moved forward and backward by the hydraulic cylinder 1, whereby the outlet 3d of the nozzle body 3 is opened and closed.

The hydraulic cylinder 1 used here is generally a double-acting type, and the rod-side hydraulic chamber 8 and the head-side hydraulic chamber 9 of the cylinder body 6 are connected to an oil passage 8a, respectively. It is connected to the nozzle movement switching valve 10 via 9a.

The nozzle movement switching valve 10 is a 4-port 3-position electromagnetic switching valve, and has A port and B port at the neutral position.
The port and the D port are communicated with each other, and when the solenoid 10a is energized and switched to the right side in the figure, the A port and the C port are communicated with each other, and the B port and the D port are communicated with each other, and the solenoid 10b is energized. When switched to the left side, the A port and the D port and the B port and the C port are communicated with each other.

The nozzle movement switching valve 10 has an A port connected to the rod side hydraulic chamber 8 of the cylinder body 6 through an oil passage 8a, and a B port connected to the head side hydraulic chamber through an oil passage 9a. 9 is connected. The C port is connected to the discharge side of the hydraulic pump 12 via the oil passage 12a, and
The port is connected to the oil tank 14 via an oil passage 14a having a cooler 13 interposed therein. Although not shown, the hydraulic pump 12, the cooler 13, and the oil tank 14 form a part of a hydraulic device including many actuators including this cylinder and many valves. The cooler 13 is controlled and operated so that the hydraulic fluid in the oil tank 14 has a constant temperature (generally around 40 ° C.).

In the needle nozzle 2 having the above structure, when the molten resin is supplied, the solenoid 10a is energized to switch the nozzle movement switching valve 10 to the left side in the drawing. The hydraulic oil supplied from the hydraulic pump 12 reaches the rod-side hydraulic chamber 8 through the oil passage 12a, the C port and the oil passage 8a,
The needle pin 5 is moved to the right side and retracted. As a result, the outflow port 3d is opened, and the molten resin supplied from the inflow port 3a flows out from the opened outflow port 3d through the horizontal hole 3b and the vertical hole 3c to a cavity (not shown).

When the resin supply is stopped, the solenoid 10b is energized to switch the nozzle movement switching valve 10 to the right side in the figure. The hydraulic oil supplied from the hydraulic pump 12 reaches the head side hydraulic chamber 9 through the oil passage 12a and the oil passage 9a, and moves the needle pin 5 to the left. As a result, the outlet 3d is closed and the supply of the molten resin is stopped.

In the conventional hydraulic cylinder 1 shown above, heat is prevented from damaging the packing 15 provided on the outer circumference of the piston rod, or in the hydraulic chambers 8 and 9 of the cylinder body 6. The following two cooling mechanisms are connected in order to prevent deterioration of the hydraulic oil.

That is, the first cooling mechanism is the nozzle body 3
The distance between the hydraulic cylinder 1 and the hydraulic cylinder 1 is widened, and the extension bracket 16 is provided between them, which makes it difficult for heat to be transferred from the nozzle body 3 in the high temperature state to the hydraulic cylinder 1. The second cooling mechanism is that the radiation fins 17 are provided on the outer periphery of the needle pin 2, and the radiation fins 17 increase the amount of heat radiation from the needle pins 2.

[0013]

However, in the cooling mechanism for the hydraulic cylinder having the above structure, the distance between the nozzle body 3 and the hydraulic cylinder 1 is widened, and the extension bracket 16 which is an extra member is provided. Since the radiating fins 17 that require a relatively large occupied space are provided, there is a drawback that the size of the entire device increases.

On the other hand, as another mechanism for cooling the hydraulic cylinder, a water passage is provided in the wall portion of the hydraulic cylinder 1 to allow cooling water to pass therethrough, or a jacket is provided on the outer peripheral portion of the hydraulic cylinder 1. There is also a structure to supply water to forcibly cool.

However, even in this type of cooling mechanism, a water circulating mechanism dedicated to cooling is required, and the structure of the entire apparatus becomes complicated. In addition, the structure of the hydraulic cylinder itself may be complicated, resulting in high cost.

The present invention has been made in view of the above circumstances, and is intended to perform cooling by using a hydraulic fluid for operating a hydraulic cylinder. A cooling water passage is provided in a wall portion of a cylinder body or a water cooling jacket. To provide a cooling mechanism for a hydraulic cylinder, which can perform cooling without providing a dedicated cooling means such as forming, has a simple structure, prevents an increase in size of the device, and can perform desired cooling while reducing cost. The purpose is.

[0017]

In order to achieve this object, in the invention according to claim 1, at least one pressure chamber of the cylinder body is provided with two ports, and a hydraulic fluid circulation path is connected to the ports. In addition, the liquid cooling means is interposed in the working liquid circulation path.

According to a second aspect of the invention, in addition to the first aspect of the invention, the pressure chamber to which the hydraulic fluid circulation path is connected is a pressure chamber formed on the rod side of the cylinder body. did.

According to a third aspect of the present invention, in addition to the above-described second aspect, the liquid supplied from the liquid supply source is introduced into either the rod side pressure chamber or the head side pressure chamber. Is provided, and a bypass fluid passage that branches from a fluid passage extending from the fluid pressure switching valve to the head-side pressure chamber and extends to the rod-side pressure chamber is provided. A two-position switching valve for switching to either of the two positions of shutoff and opening is provided in the above.

[0020]

According to the present invention, the working fluid kept at a constant temperature (around 40 ° C.) is passed through the working fluid circulating passage connected to the pressure chamber of the cylinder body and the cooling means interposed in the working fluid circulating passage. Supplied. As a result, the cylinder can be forcibly cooled, so that it is possible to prevent the working oil from being deteriorated by heat and the packing around the piston rod from being damaged.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same components as those described in the conventional example are designated by the same reference numerals to simplify the description.

In the present embodiment, as shown in FIG. 1, the pressure oil supplied from the hydraulic pump 12 which is a hydraulic pressure supply source is connected to the first port 20 formed in the rod side pressure chamber 8. A nozzle movement switching valve 10 is provided for switching to either the passage 8a or the oil passage 9a connected to a port 21 formed in the pressure chamber on the head side. A branch from an oil passage 9a extending to a port 21 formed in the pressure chamber 9 on the head side is branched to a second port 22 newly formed in the pressure chamber 8 on the rod side separately from the first port 20. An extended bypass oil passage 23 is provided.

Then, in the bypass oil passage 23, a two-position switching valve 24 for switching the bypass oil passage 23 to either a closed state or an open state, and a flow rate adjusting valve for adjusting the flow rate of the pressure oil flowing through the bypass oil passage 23. 25 are interposed. Two
When the position switching valve 24 is in the neutral position, both ports are in a cutoff state, and when the solenoid 24a is energized and switched to the right side in the drawing, both ports are in a communication state. Here, the oil passage 12a, the oil passage 8a, the bypass oil passage 23,
The oil passage 9a and the oil passage 14a constitute a pressure oil circulation passage 27 that circulates pressure oil in the pressure chamber of the cylinder body.

The adjustment of the flow rate adjusting valve 25 is performed by moving the needle pin 5 as a piston rod in the left-right direction from the nozzle movement switching valve 10 to the hydraulic chamber 8 on the rod side or the hydraulic chamber 9 on the head side. The flow rate of the pressure oil flowing through the bypass oil passage 23 is appropriately set to be smaller than the flow rate of the pressure oil flowing into the bypass oil passage 23.

In addition, in the hydraulic cylinder of this embodiment, the hydraulic cylinder is attached so as to directly contact the rear surface of the needle nozzle 2 without a gap. Further, no fin for cooling is provided on the outer periphery of the needle pin 5.

The point that the needle nozzle 2 operated by the hydraulic cylinder 1 controls the supply and stop of the supply of the molten resin, and that the cooler 13 is provided in the oil passage 13a connected to the nozzle movement switching valve 10, This is the same as the conventional one described above.

Next, the operation of the cooling mechanism for the hydraulic cylinder having the above structure will be described. When the needle pin 5 is retracted to supply the molten resin (when it is moved to the right in FIG. 1), the solenoid 24a is de-energized and the two-position switching valve 24 is switched to the neutral position left side. The bypass oil passage 23 is turned off. Then, the solenoid 10a is energized to switch the nozzle movement switching valve 10 to the left side in the figure. As a result, from the hydraulic pump 12 to the oil passage 12a
The hydraulic oil supplied to the nozzle movement switching valve 10 via the oil reaches the rod-side hydraulic chamber 8 via the oil passage 8a, moves the needle pin 5 to the right, and retracts it to the position where it abuts the stopper 7. At the same time, the pressure oil in the hydraulic chamber 9 on the head side is
It flows out to the oil tank 14 through the oil passage 9a, the port B, the port D, and the oil passage 14a. As a result, the outlet 3d of the nozzle body 3 shown in FIG. 1 is opened, and the molten resin supplied from the inlet 3a is discharged from the outlet 3d opened through the horizontal holes 3b and the vertical holes 3c, not shown. Supplied to mold cavity.

When the hydraulic cylinder 1 is cooled while the molten resin can be supplied in this manner, the solenoid 24a is energized to switch the two-position switching valve 24 to the right to open the bypass oil passage 23 (FIG. 2). reference). Then, the hydraulic oil from the hydraulic pump 12 receives the oil passage 12a, the switching valve 10, the oil passage 8a, the hydraulic chamber 8, the port 22, the adjusting valve 25, and the switching valve 2.
4, the switching valve 10 and the cooler 13 in this order to the oil tank 1
Return to 4. At this time, since the adjusting valve 25 is properly adjusted, the pressure in the hydraulic chamber 8 is high and the retracted position of the cylinder is maintained.

As described above, since the hydraulic fluid in the oil tank 14 having a constant temperature is circulated in the hydraulic chamber 8, the heat conducted from the nozzle body 6 and the needle pin 5 is removed to cool it. Will be done. Since the hydraulic cylinder 1 is cooled by the circulating pressure oil in this way, the hydraulic cylinder 1 is arranged far away from the heat source portion for heat insulation, and the cylinder body 6 is provided with a water jacket and a cooling passage. Things become unnecessary.

On the other hand, when the needle pin 5 is advanced to stop the supply of the molten resin (when it is moved to the left in FIG. 1), the solenoid 24a is de-energized and the two-position switching valve 24 is neutralized. The position is switched to the left side, and the bypass oil passage 23 is cut off. And the solenoid 10
By energizing b, the nozzle movement switching valve 10 is switched to the right side in the figure. The hydraulic oil supplied from the hydraulic pump 12 to the nozzle movement switching valve 10 via the oil passage 12a reaches the head side hydraulic chamber 9 via the oil passage 9a and moves the needle pin 5 to the left side to move the needle pin 5 to the left side. Is advanced to a position where the tip of the abuts the outlet 3d. At the same time, the pressure oil in the rod-side hydraulic chamber 8 flows out from the port 20 and reaches the oil tank 14 via the oil passage 8a, the nozzle movement switching valve 10 and the oil passage 14a. As a result, the outlet 3d of the nozzle body 3 is closed and the supply of molten resin is stopped.

When the hydraulic cylinder 1 is cooled while the supply of the molten resin is stopped in this way, the solenoid 2
4a is energized and the two-position switching valve 24 is switched to the right side to open the bypass oil passage 23 (see FIG. 3). Then, the pressure oil supplied from the nozzle movement switching valve 10 to the hydraulic chamber 9 through the oil passage 9a is transferred to the two-position switching valve 24 and the flow rate adjusting valve 25.
After passing through the bypass oil passage 23, the oil is supplied from the port 22 to the rod-side hydraulic chamber 8, further flows out of the port 20, reaches the A port of the nozzle movement switching valve 10 through the oil passage 8a, and further from there. Return to oil tank 14 through D port and cooler 13. In this case, since the pressure oil flowing to the bypass passage 23 is given flow passage resistance by the bypass oil passage 23 and the flow rate adjusting valve 25, by maintaining the pressurization of the pressure oil in the pressure chamber 9, The pin is circulated while maintaining the state in which the pin is moved to the forward end position. The pressure oil returned to the oil tank 14 is returned from the hydraulic pump 12 to the oil passage 12 again.
is supplied to a.

The cooling mechanism for the hydraulic cylinder according to the present invention is not limited to the above-mentioned embodiment, and the specific configurations such as the shape and size of each member can be appropriately changed in practice.

For example, in the above-described embodiment, the original path such as the oil passage 8a or 9a is utilized, and the oil passage 9a extending from the nozzle movement switching valve 10 to the port formed in the pressure chamber on the head side is branched. Although the bypass oil passage 23 extending to the port 22 formed in the pressure chamber 8 on the rod side is added to form the circulation passage for cooling the pressure oil, the present invention is not limited to this, and the circulation passage is newly formed. It may be configured.

Further, in the above embodiment, the cooling is performed only when the cylinder is stopped. However, the present invention is not limited to this, and the cooling may be performed during the cylinder operation. In this case, this can be done simply by omitting the two-position switching valve 24. However, in this case, the operating speed of the cylinder is reduced by the flow rate of the pressure oil flowing through the cooling circulation path, resulting in a loss of the piston operation flow rate, and the cylinder operating speed is correspondingly reduced.

As described above, according to the present invention, the following excellent effects are obtained.

According to the first aspect of the invention, the working fluid is used for cooling, and for cooling, a cylinder body is provided with a jacket, a wall of the cylinder is provided with a cooling water passage, or the like. There is no need to provide special cooling means,
The configuration is simple, the desired size of the device can be prevented, and the cost can be reduced while the desired cooling can be performed.

According to the second aspect of the invention, the pressure chamber on the rod side of the cylinder body, which is arranged near the high temperature generating portion, can be positively cooled, in other words, the pressure chamber that tends to become high temperature can be cooled. , Efficient cooling can be performed.

According to the third aspect of the present invention, the existing liquid passage extending from the hydraulic fluid switching valve to the port formed in the pressure chamber on the head side can be used as a circulation passage for cooling. Cooling is possible by simply adding a simple structure to the structure, so that the structure can be further simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing the operation of the embodiment.

FIG. 3 is a hydraulic circuit diagram showing the operation of the same embodiment.

FIG. 4 is a diagram illustrating a conventional cooling mechanism for a hydraulic cylinder.

[Explanation of symbols]

 1 Hydraulic Cylinder 2 Needle Nozzle 3 Nozzle Main Body 5 Needle Pin 6 Cylinder Main Body 8 Rod Side Hydraulic Chamber (Pressure Chamber) 9 Head Side Hydraulic Chamber (Pressure Chamber) 10 Nozzle Movement Switching Valve 12 Hydraulic Pump 13 Cooler (Liquid Cooling Means) 20 port 21 port 22 port 23 Bypass oil passage (bypass liquid passage) 24 2 Position switching valve 25 Flow rate adjusting valve 27 Pressure oil circulation passage (hydraulic circulation passage)

Claims (3)

[Claims] 1. A cylinder body, wherein at least one pressure chamber is provided with two ports, a working fluid circulation passage is connected to the ports, and a liquid cooling means is interposed in the working fluid circulation passage. Cooling mechanism for hydraulic cylinders. 2. The cooling mechanism for a hydraulic cylinder according to claim 1, wherein the pressure chamber to which the hydraulic fluid circulation path is connected is a pressure chamber formed on the rod side of the cylinder body. Cooling mechanism for pressure cylinder. 3. The cooling mechanism for a hydraulic cylinder according to claim 2, wherein the liquid pressure is switched so as to guide the liquid supplied from the liquid supply source to either the rod side pressure chamber or the head side pressure chamber. A valve is provided, and a bypass fluid passage that branches from the fluid pressure switching valve to the head-side pressure chamber and extends to the rod-side pressure chamber is provided. Switch to either of 2 positions 2
A cooling mechanism for a hydraulic cylinder, wherein a position switching valve is interposed.