JP2755092B2 - Hydraulic cylinder cooling mechanism - Google Patents

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, such as damage to packing at a sliding portion of a piston rod or deterioration of hydraulic oil in a hydraulic chamber. Therefore, various devices have been devised in order to minimize the effects of conduction heat and radiant heat received from the high-temperature portion of the mechanism.

FIG. 4 shows an example of a hydraulic cylinder devised for cooling. The hydraulic cylinder 1 shown in FIG. 1 is provided as a means for driving a needle nozzle 2 of a resin molding machine. The needle nozzle 2 applies a molten resin injected from a plasticizing and injection mechanism (not shown) of a resin to a molding machine at a subsequent stage. Is used to supply or stop supply to a mold cavity (not shown).

An inlet 3a is formed on the side of the nozzle body 3, and the molten resin entering through the inlet 3a communicates with the lateral hole 3b extending radially in the nozzle body 3 and the lateral hole 3b. Through a vertical hole 3c formed along the central axis of the nozzle main body 3, it is supplied from an outlet 3d formed at the tip of the nozzle main body 3. Note that 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 base end of the needle pin 5 for opening and closing the outlet 3d of the nozzle body 3 projects outside the nozzle body 3 through the vertical hole 3c, and the hydraulic cylinder 1 is attached to the base end. Have been. The needle pin 5 integrated with or connected to the piston rod is moved forward and backward by the hydraulic cylinder 1, thereby opening and closing the outlet 3 d of the nozzle body 3.

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

[0007] The nozzle movement switching valve 10 is a 4-port, 3-position type electromagnetic switching valve.
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 and C ports, and the B port and the D port are communicated with each other, and the solenoid 10b is energized and When the port is switched to the left side, the A port and the D port, and the B port and the C port are connected to each other.

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

When supplying molten resin to the needle nozzle 2 having the above configuration, the solenoid 10a is energized to switch the nozzle movement switching valve 10 to the left side in the figure. The hydraulic oil supplied from the hydraulic pump 12 reaches the hydraulic chamber 8 on the rod side via the oil passage 12a, the C port and the oil passage 8a.
The needle pin 5 is moved to the right and retracted. As a result, the outlet 3d is opened, and the molten resin supplied from the inlet 3a flows out of the outlet 3d opened through the horizontal hole 3b and the vertical hole 3c to a cavity (not shown).

When the supply of the resin 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 hydraulic chamber 9 on the head side through the oil passage 12a and the oil passage 9a, and moves the needle pin 5 to the left. Thereby, the outlet 3d is closed, and the supply of the molten resin is stopped.

Here, in the hydraulic cylinder 1 as an example of the prior art shown above, the packing 15 provided on the outer periphery of the piston rod is prevented from being damaged by heat, or the hydraulic chambers 8 and 9 of the cylinder body 6 are prevented from being damaged. In order to prevent the deterioration of the hydraulic oil, two cooling mechanisms shown below are connected.

That is, the first cooling mechanism is the nozzle body 3
And the hydraulic cylinder 1 is widened, and an extension bracket 16 is provided between them, so that heat is hardly transmitted from the nozzle body 3 in a high temperature state to the hydraulic cylinder 1. The second cooling mechanism is characterized in that a radiation fin 17 is provided on the outer periphery of the needle pin 5, and the radiation fin 17 increases the amount of heat radiation from the needle pin 5.

[0013]

However, in the hydraulic cylinder cooling mechanism having the above-described structure, the space between the nozzle body 3 and the hydraulic cylinder 1 is increased, and the extension bracket 16 which is an extra member is provided. Since the heat radiating fins 17 requiring a large space are provided, there is a drawback that the entire device becomes large.

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 flow through the water passage, or a jacket is provided in the outer peripheral portion of the hydraulic cylinder 1 to provide a cooling passage therein. There is also a structure in which water is supplied for forced cooling.

However, even with this type of cooling mechanism, a water circulation mechanism dedicated to cooling is required, and the configuration of the entire apparatus becomes complicated. In addition, the structure of the hydraulic cylinder itself is complicated, and there is a disadvantage that the cost is increased.

The present invention has been made in view of the above circumstances, and performs cooling by using a hydraulic fluid for operating a hydraulic cylinder. A water cooling jacket is provided or a cooling water passage is formed in a wall of a cylinder body. Provided is a cooling mechanism of 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 apparatus, and can perform desired cooling while reducing costs. It is intended for.

[0017]

According to a first aspect of the present invention, a cooling mechanism for a hydraulic cylinder includes a first hydraulic passage connected to a head-side pressure chamber of a cylinder body, and a rod-side pressure chamber. A second fluid passage connected to the first fluid passage, a fluid pressure switching valve for connecting one of the first and second fluid passages to a fluid supply source, and a branch from the first fluid passage, wherein A bypass fluid passage connected to the pressure chamber and cooling means for cooling the working fluid circulating through the fluid passage, wherein the bypass fluid passage is switched to open or close the bypass fluid passage. A valve and an adjusting valve for adjusting the flow path resistance of the bypass flow path are provided.

[0018]

[0019]

[0020]

According to the present invention, the working fluid can be circulated while sending the working fluid from the fluid passage connected to the head-side pressure chamber to the rod-side pressure chamber via the bypass passage. The working fluid maintained at a constant temperature (around 40 ° C.) is supplied by the cooling means interposed in the cooling medium. As a result, the hydraulic cylinder can be forcibly cooled using the hydraulic fluid as a heat medium, so that it is possible to prevent the hydraulic oil from deteriorating due to the heat and to prevent the packing around the piston rod from being damaged. In the bypass passage,
Since an appropriate pressure loss can be given by providing a regulating valve, when the hydraulic cylinder is operated at the stroke end position, the pressure of the pressure chamber on the pressurizing side of the cylinder body is made higher than the pressure of the pressure chamber on the other side. Can also be reliably maintained at a high pressure.

[0021]

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 denoted by the same reference numerals, and description thereof will be simplified.

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

The bypass oil passage 23 has a two-position switching valve 24 for switching the bypass oil passage 23 between a closed state and an open state, and a flow control valve for adjusting the flow rate of the pressure oil flowing through the bypass oil passage 23. 25 are interposed. 2
When the position switching valve 24 is in the neutral position, both ports are in a shut-off state, and when the solenoid 24a is energized and switched to the right side in the figure, both ports are in a communicating 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 path 27 that circulates pressure oil in a pressure chamber of the cylinder body.

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

In the hydraulic cylinder of this embodiment, the hydraulic cylinder is mounted so as to directly contact the rear surface of the needle nozzle 2 without any space. Further, no cooling fin 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 the point that the cooler 13 is provided in the oil passage 14a connected to the nozzle movement switching valve 10 are as follows. This is the same as the conventional one described above.

Next, the operation of the cooling mechanism for a hydraulic cylinder having the above configuration will be described. When the needle pin 5 is retracted to supply the molten resin (when the needle pin 5 is moved rightward in FIG. 1), the energization of the solenoid 24a is cut off and the two-position switching valve 24 is switched to the neutral position left side. Then, the bypass oil passage 23 is set to the cutoff state. Then, the solenoid 10a is energized to switch the nozzle movement switching valve 10 to the left side in the figure. As a result, the hydraulic pump 12
The hydraulic oil supplied to the nozzle movement switching valve 10 through the oil passage reaches the rod-side hydraulic chamber 8 via the oil passage 8a, moves the needle pin 5 to the right side, and retreats to a position where it comes into contact with the stopper 7. At the same time, the pressure oil in the hydraulic chamber 9 on the head side is
The oil flows out to the oil tank 14 via the oil passage 9a, the port B, the port D, and the oil passage 14a. Thereby, 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 hole 3b and the vertical hole 3c and is not shown. Supplied to the mold cavity.

In order to cool the hydraulic cylinder 1 in a state in which the molten resin can be supplied, the solenoid 24a is energized to switch the two-position switching valve 24 to the right side, thereby opening the bypass oil passage 23 (FIG. 2). reference). Then, the hydraulic oil from the hydraulic pump 12 is supplied to the oil passage 12a, the nozzle movement switching valve 10, the oil passage 8a, the hydraulic chamber 8, the port 22, the adjustment valve 25,
It returns to the oil tank 14 via the switching valve 24, the nozzle movement switching valve 10, and the cooler 13 in this order. At this time, since the adjustment valve 25 is appropriately adjusted, the pressure in the hydraulic chamber 8 is high and the retreat position of the cylinder is maintained.

As described above, the hydraulic fluid in the oil tank 14 having a constant temperature is circulated in the hydraulic chamber 8, so that the heat conducted from the nozzle body 3 and the needle pin 5 is removed and cooling is performed. Will do it. Since the hydraulic cylinder 1 is configured to be cooled by the circulating pressure oil in this manner, the hydraulic cylinder 1 is disposed far away from the heat source portion for heat insulation, and a water jacket and a cooling passage are provided in the cylinder body 6. It becomes unnecessary.

On the other hand, when the needle pin 5 is advanced to stop the supply of the molten resin (when the needle pin 5 is moved to the left in FIG. 1), the energization of the solenoid 24a is stopped and the two-position switching valve 24 is set to the neutral position. The position is switched to the left side, which is the position, and the bypass oil passage 23 is closed. And the solenoid 10
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 hydraulic chamber 9 on the head side via the oil passage 9a, moves the needle pin 5 to the left side, and Is advanced to a position where the tip of the hole comes into contact with the outlet 3d. At the same time, the pressure oil in the rod-side hydraulic chamber 8 flows out of 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. Thus, the outlet 3d of the nozzle body 3 is closed, and the supply of the molten resin is stopped.

When cooling the hydraulic cylinder 1 with the supply of the molten resin stopped, the solenoid 2
4a, the two-position switching valve 24 is switched to the right 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 via the oil passage 9a is changed to the two-position switching valve 24 and the flow regulating valve 25.
Is supplied from the port 22 to the hydraulic chamber 8 on the rod side through the bypass oil passage 23, 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. It returns to the oil tank 14 via the D port and the cooler 13. In this case, the pressurized oil flowing to the bypass passage 23 is provided with a flow path resistance by the bypass oil passage 23 and the flow control valve 25. It is circulated while maintaining the state where 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.
a.

Incidentally, the cooling mechanism of the hydraulic cylinder of the present invention is not limited to the above-described embodiment, and the specific configuration such as the shape and size of each member can be appropriately changed upon implementation.

For example, in the above embodiment, the oil path 9a is branched from the oil passage 9a extending from the nozzle movement switching valve 10 to the port formed in the pressure chamber on the head side while utilizing the original path such as the oil path 8a or 9a. The circulation path for cooling the pressure oil is formed by adding a bypass oil path 23 extending to the port 22 formed in the pressure chamber 8 on the rod side. However, the invention is not limited to this, and a new circulation path is formed. It may be configured.

In the above embodiment, cooling is performed only when the cylinder is stopped. However, the present invention is not limited to this, and cooling may be performed during cylinder operation.

As apparent from the above description, the present invention provides a bypass fluid passage from a fluid passage connected to the head-side pressure chamber to the rod-side pressure chamber, and a switching valve provided in this fluid passage to provide the bypass passage. Since the fluid path is opened and closed and the flow path resistance of the bypass fluid path is adjusted by the regulating valve, the working fluid flowing to the head side pressure chamber is sent to the rod side pressure chamber via the bypass fluid path. By moving the cylinder in the forward (extending) direction or maintaining the forward state, the hydraulic fluid that has passed through the rod-side pressure chamber is conveyed to the head-side pressure chamber via the bypass path. The cylinder can be moved in the retreating (retracting) direction or maintained in the retreating state. Further, since the working fluid is cooled during such circulation, oil is supplied to the rod-side pressure chamber close to the heat source in the forward position, the retracted position, or any state during the operation to reach those positions. By circulating, the entire hydraulic cylinder can be effectively cooled. Further, such cooling using the working fluid as a refrigerant can be performed without changing the structure of the hydraulic cylinder itself, by-pass fluid path, switching valve,
It can be easily realized only by changing the hydraulic system such as the adjustment valve. Further, the pressure in the pressure chamber on the pressurized side of the cylinder main body is increased when the hydraulic cylinder is operated at the stroke end position by applying a pressure loss to the bypass fluid passage by the action of the regulating valve. The hydraulic cylinder can be maintained in a predetermined operating state by reliably maintaining the pressure higher than the pressure in the pressure chamber.

[0036]

[0037]

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing one 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 embodiment.

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

[Explanation of symbols]

 Reference Signs List 1 hydraulic cylinder 2 needle nozzle 3 nozzle body 5 needle pin 6 cylinder body 8 hydraulic chamber (pressure chamber) on rod side 9 hydraulic chamber (pressure chamber) on head side 10 nozzle movement switching valve 12 hydraulic pump 13 cooler (liquid cooling means) 20 port 21 port 22 port 23 bypass oil passage (bypass fluid passage) 24 2-position switching valve 25 flow control valve 27 pressure oil circulation passage (hydraulic circulation passage)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F15B 21/04 B29C 45/82

Claims (1)

(57) [Claims] A first fluid passage connected to a head-side pressure chamber of the cylinder body; a second fluid passage connected to a rod-side pressure chamber; and one of the first and second fluid passages. A liquid pressure switching valve for connecting a liquid supply source, a bypass liquid path branched from the first liquid path and connected to the rod-side pressure chamber,
Cooling means for cooling the hydraulic fluid circulating in these fluid paths, the bypass fluid path includes a switching valve for opening or closing the bypass fluid path, and a flow path resistance of the bypass flow path. A cooling mechanism for a hydraulic cylinder, comprising: an adjusting valve for adjusting pressure.