JPH02486Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a hydraulic power unit used in a hydraulic elevator or the like.

[Prior art]

A conventional hydraulic power unit disclosed in, for example, Japanese Utility Model Application Publication No. 56-91901 will be explained with reference to FIG.

In FIG. 1, 1 is a hydraulic power unit, which includes the following parts. 2 is an oil tank that stores hydraulic oil 13; 3 is a hydraulic pump that generates pressure oil;
4 is an electric motor that drives the hydraulic pump 3; 5 is a coupling that connects the shafts of the hydraulic pump 3 and the electric motor 4;
6 is a control valve that controls the flow of pressure oil; 7 is a suction pipe that connects the bottom of the oil tank 2 and the hydraulic pump 3; 8 is a discharge pipe that connects the hydraulic pump 3 and the control valve 6; 9 is the control valve 6 and the oil tank A return pipe 10 connects the control valve 6 to a hydraulic cylinder (not shown). Further, 11 is a rod-shaped immersion heater of the oil temperature raising device, and 12 is wiring for the immersion heater 11.

In general, the characteristics of the hydraulic pump 3 and control valve 6 change greatly depending on the oil temperature, so in a hydraulic power unit for a hydraulic elevator, the oil temperature in the oil tank 2 is kept constant in order to make the elevator car comfortable to ride. It is necessary to keep it within range. Therefore, an oil temperature raising device is used which is connected to a power source and raises the oil temperature when the oil temperature of the hydraulic oil 13 in the oil tank 2 falls below a certain temperature.

The immersion heater 11 is used in the oil temperature raising device, but since it is generally used in flammable mineral hydraulic oil 13, the surface temperature of the heater is lower than that of the hydraulic oil 13 in order to prevent fires. It is necessary to design the product so that the temperature does not rise above a certain level below the flash point.

However, in the conventional immersion heater 11, in order to suppress the current density, the surface area of the heater must be increased, and the heater becomes large compared to the electric capacity. There was a problem that the price was high. In addition, since the heater used nichrome wire, its lifespan was short, and since only the rod-shaped heater part was heated, the hydraulic oil 13 in the oil tank 2 was not heated uniformly in each part, and the oil temperature did not change. There was a problem with unevenness.

[Summary of the idea]

This idea attempts to solve the above-mentioned problem. By installing a flat ceramic heater with multiple through holes at the bottom of the oil tank, there is no risk of fire, and it is compact. The purpose of the present invention is to provide a hydraulic power unit that has a long life and is equipped with an inexpensive oil temperature raising device.

[Example of idea]

An embodiment of this invention will be described below with reference to FIGS. 2 and 3.

In FIG. 2, the same reference numerals as those in FIG.
As shown in FIG. 3, the spacer 1 is a flat plate that broadly covers the bottom of the oil tank 2, and is provided with a large number of through holes 14a that penetrate in the vertical direction.
5, it is supported on the bottom of the oil tank 2 with an appropriate gap therebetween.

In the embodiment configured as described above, by using the ceramic heater 14 whose shape can be selected, it is easy to form a flat heater 14 that can widely and uniformly cover the bottom surface of the oil tank 2. can be obtained. Furthermore, since the ceramic heater 14 is a semiconductor, when the surface temperature of the heater exceeds a certain level, the resistance increases rapidly and the current decreases.
Therefore, it does not become red hot and there is no risk of the hydraulic oil 13 in the oil tank 2 catching fire. Furthermore, the ceramic heater 14 generates heat over its entire surface, thereby allowing the oil tank 2 to
It is easy to keep the temperature of the hydraulic oil 13 in each part almost uniform, and unlike nichrome wire, there is no risk of wire breakage, so it has a long life. And ceramic heater 14
By providing a through hole 14a in the ceramic heater 14 and providing a gap between the ceramic heater 14 and the bottom of the oil tank 2, as shown by the arrow in FIG. Active natural convection of the oil 13 occurs, and each part within the oil tank 2 can be kept at a uniform oil temperature. By installing the ceramic heater 14 in the oil tank 2 in this manner, the oil tank 2 can be made smaller, and the hydraulic power unit 1 itself can also be made smaller and manufactured at a lower cost.

In the above embodiment, the ceramic heater 14 is provided with the through holes 14a consisting of a large number of round holes.
In this invention, as shown in FIG. 4, a large number of elongated through holes 14a may be arranged in parallel in the ceramic heater 14, or the through holes may be provided so that the ceramic heater is arranged in a lattice shape. The invention does not use a spacer, as shown in Figure 5,
A ceramic heater 14 having a shape in which both side portions or four corner portions are bent downward may also be used, and in these cases, the same effects as those of the above-mentioned embodiments can be obtained.

[Effect of idea]

As explained above, this idea is to install a ceramic heater with multiple through holes inside the oil tank, covering the bottom of the oil tank with the heater and leaving a gap between the bottom and the heater. The oil temperature in the oil tank can be heated uniformly and below a certain temperature, there is no risk of fire, and the service life is long.Furthermore, the oil temperature raising device and oil tank can be downsized, and the overall However, it has the effect of providing an inexpensive hydraulic power unit.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a conventional hydraulic power unit, Fig. 2 is a view corresponding to Fig. 1 showing a hydraulic power unit according to an embodiment of the invention, Fig. 3 is a plan view of the ceramic heater, and Fig. 4. 5 is a plan view showing a modified example of the ceramic heater according to this invention;
The figure is a side view showing another modification of the ceramic heater. 1... Hydraulic power unit, 2... Oil tank,
12... Wiring, 13... Hydraulic oil, 14... Ceramic heater, 14a... Through hole. In addition, the same parts or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Scope of utility model registration request] A hydraulic power unit characterized in that a flat ceramic heater having a plurality of vertical through holes is installed in an oil tank so as to widely cover the bottom of the tank with a gap between the heater and the bottom of the tank. .