JPH0442532Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] Industrial application field The present invention relates to a pump for delivering liquids such as fuel oil and lubricating oil.

Conventional technology As a fuel pump for a conventional kerosene combustor,
Electromagnetic pumps are widely used, but since such pumps are large in size and are frequency controlled, they have the disadvantage that when a low flow rate is used, the flow rate pulsates and combustion becomes unstable. Furthermore, these electromagnetic pumps generate a lot of noise, consume a lot of power like electric pumps, and are expensive compared to their capacity.

Therefore, it has been proposed to use a pump that uses a piezoelectric vibrator instead of the conventional electromagnetic pump. An oil feed pump is disclosed (FIG. 4). The oil pump in this example has a piezo element c on a metal disc b.
Check valves e and f are provided at both ends of a liquid pressurizing chamber d, which is constructed by opposing the vibrator a obtained by joining the vibrator a, so that the vibrator a sucks liquid by alternately deforming into concave and convex shapes. It is designed to be discharged.

However, with this type of pump, the phase of the input to the vibrator a can be controlled using a commercial power source, which has the advantage of reducing pulsation even at low flow rates, but since the amount of deformation of the vibrator a is relatively small, the required flow rate is In order to ensure this, it is necessary to take a large area, and the shape of the liquid pressurizing chamber d has to become large. As a result, air and the like tend to remain in the liquid pressurizing chamber, which absorbs changes in volume and deteriorates the pump's function, and also causes problems such as a delay in stabilizing the liquid delivery rate.

In order to solve the above-mentioned problems with conventional piezoelectric pumps, the inventors of the present invention created a pump section that sucks in and discharges liquid in a fixed direction using a reciprocating piston below the liquid surface, and supports it in a cantilevered manner. A small piezoelectric pump characterized in that a piezoelectric vibrator is provided above the liquid level, and the motion of the vibrating end of the piezoelectric vibrator is transmitted to the piston by a joint member provided through the liquid level. We have proposed and applied for a patent.

Problems to be Solved When such a new piezoelectric pump is used, for example, as an oil pump for a kerosene-burning heater, it is installed so that the pump part is immersed in oil inside an oil tank, but the kerosene is not consumed or refilled. It is inevitable that the oil level will fluctuate up and down depending on the situation. Once the oil tank was empty, air bubbles remained in the vicinity of the strainer at the pump's intake port without being replaced with kerosene, causing the problem that oil delivery became unstable even when the pump was started the next time. In addition, if there is dirt in the oil, the piston may become trapped and break down easily, and if a strainer is installed in the piston, the air bubbles generated as the oil level fluctuates will interfere with the lubrication of the piston. There was a problem that the oil flow rate became unstable.

Therefore, the object of the present invention is to provide a piezoelectric pump for oil transfer that does not cause operational problems due to dust, air bubbles, etc. even when the oil level fluctuates.

[Structure of the idea]

Means for Solving the Problems The object of the present invention as described above is to provide a pump chamber having check valves at both ends and a cylinder portion formed in the side wall portion, and a piston slidably fitted into the cylinder portion. A pump section consisting of a pump part is installed below the lower limit oil level in the oil tank, a piezoelectric vibrator supported in a cantilevered manner is installed above the higher limit oil level, and the movement of the vibrating end of the piezoelectric vibrator is transmitted to the joint member. Therefore, in the piezoelectric pump configured to transmit power to the piston, the partition wall that separates the pump portion from the internal space of the oil tank has at least both a position higher than the upper limit oil level and a position lower than the lower limit oil level. This is achieved by a piezoelectric pump characterized in that it has a window extending over the area and is blocked by a filter medium.

An example of the piezoelectric pump of the present invention is shown in FIG. In the figure, 1 is a pump case, and a pump chamber 1a is formed at its lower end. A suction port 1c is provided on the lower side of the pump chamber 1a via an inlet check valve 1b, and a passage communicating with the supply port 1e via an outlet check valve 1d is provided on the upper side. Further, a cylinder part 1f is provided on the side of the pump chamber 1a, and a piston 2 is slidably mounted on the cylinder part 1f.

3 is a plate-shaped piezoelectric vibrator, the upper end 3a is fixed to form a cantilever shape, and the lower end 3b is fixed by applying an alternating voltage to electrodes provided on both sides of the piezoelectric vibrator.
is designed to vibrate (in the left-right direction in the figure). An electrically insulating joint 4 is fixed to the vibrating end 3b of the piezoelectric vibrator, and a rod-shaped joint member 5 is provided along the extending direction of the piezoelectric vibrator 3 via the joint 4.

The joint member 5 is inserted into a through hole 2a formed at the rear end of the piston 2 near its tip, and amplifies the horizontal vibration of the piezoelectric vibrator 3 and transmits it to the piston 2, so that the piston 2 It is configured to move back and forth within the

6 is a protective cover provided to surround the pump section including the pump chamber 1a portion, the suction port 1c, the cylinder section 1f, the piston 2, etc., and the window section 6a provided on the side surface is made of, for example, a fine woven mesh. It is blocked by a filter medium 7 made of a material such as the like, so that only liquid can pass through.

Here, HL is the upper limit liquid level, and LL is the lower limit liquid level. When fuel oil such as kerosene reaches the high limit oil level HL, it cannot be injected any more, and even when it reaches the lower limit level LL. For example, when this happens, an alarm signal is emitted. The window section 6
A has a wide vertical opening so that its upper side is higher than the upper limit oil level HL and its lower side is lower than the lower limit oil level LL. The filter medium 7 that blocks this window 6a is a filter medium that is fine enough to prevent the passage of dirt, etc. in the oil, and is made so that there is no gap around the window 6a. is attached to. Such filter media include:
For example, a nylon woven net with a mesh opening of about 60 μm or less may be used, but is not limited to this (FIGS. 2 and 3).

The piezoelectric vibrator 3 of the piezoelectric pump of the present invention is installed at a position higher than the upper limit oil level HL so that it does not come into contact with fuel oil, etc., and the part including the piston 2 is lower than the lower limit oil level LL. Since the fuel oil is provided at a certain position and is separated from the internal space of the oil tank by the protective cover 6, the fuel oil enters the protective cover 6 only by passing through the filter medium 7, and the pump part can be immersed therein. .

On the other hand, 8 is a control circuit, for example, 100V AC power is supplied from a power supply line 8a, and a signal line 8b
A drive signal controlled by a flow rate adjustment signal input from the piezoelectric vibrator 3 is outputted to the piezoelectric vibrator 3 via an output line 8c.

Function: In the piezoelectric pump of the present invention, the window of the protective cover surrounding the pump part is provided wide, and the fuel oil passes through the filter medium provided in the window and enters the protective cover. The oil levels inside and outside the cover are almost the same. Since the fuel oil inside the protective cover is free of dust, etc., fuel oil free of dust can be directly sucked from the pump's intake port.
The piston also operates in clean fuel oil.

[Effect of idea]

Since the piezoelectric pump of the present invention has the above-described configuration, the pump suction port and piston are constantly immersed in fuel oil that has been purified by a filter medium, and the piston is not activated by dirt, air bubbles, etc. There were no problems at all, and maintenance work such as cleaning the strainer due to dirt clogging was drastically reduced compared to when the strainer was installed directly at the suction port.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the structure of an example of the piezoelectric pump of the present invention, Fig. 2 is a front view with a partially cutaway protective cover thereof, Fig. 3 is a top view thereof, and Fig. 4 is a conventional piezoelectric pump. FIG. 3 is a cross-sectional view of the oil pump. 1...Pump case, 1a...Pump chamber, 1f
... Cylinder part, 2 ... Piston, 3 ... Piezoelectric vibrator, 4 ... Joint, 5 ... Joint member, 6 ...
...Protective cover, 6a... Window, 7... Filter medium, 8...
...control circuit.

Claims (1)

[Scope of utility model registration request] A pump section consisting of a pump chamber with check valves at each end and a cylinder formed in the side wall portion, and a piston slidably fitted into the cylinder is installed below the lower limit oil level in the oil tank, and is cantilevered. In the piezoelectric pump, the piezoelectric vibrator supported by the piston is disposed above the upper limit oil level, and the movement of the vibrating end of the piezoelectric vibrator is transmitted to the piston by a joint member. A partition wall that partitions the internal space of the oil tank is formed with a window extending over at least both a position higher than the upper limit oil level and a position lower than the lower limit oil level, and the window is blocked by a filter medium. piezoelectric pump.