JPH0533755Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention relates to an in-tank fuel pump.
In particular, the present invention relates to an in-tank fuel pump that suppresses heat generation in the armature, which is a component of the fuel pump, and prevents evaporation of fuel within the pump, thereby constantly supplying a stable amount of fuel to an injector system.

[Prior Art] Fuel pumps that send fuel to an injector system are generally classified into those that are installed outside the fuel tank and those that are installed inside the tank. That is, as shown in FIG. 5, a fuel pump _a1 is provided outside the fuel tank m, a pipe n is attached to the suction side of the fuel pump _a1 , and the pipe n is inserted into the fuel tank m. As shown in FIG. 6, a fuel pump _a2 is installed in a fuel tank m, and a discharge port o of the fuel pump _a2 is connected to an injector system by a pipe p.

However, the externally installed fuel pump _a1 shown in FIG. 5 had the following problems.

In other words, in order to install the fuel pump _a1 , the suction side pipe n has to be bent so as to straddle the wheels, but because of this, the fuel oil level c in the fuel tank m and the suction side The required suction head H between the pipe n and the pipe n inevitably becomes larger, and the pipe area becomes larger, making it more susceptible to external heat influences, so fuel evaporates within the suction side pipe n. There was a problem that pressure transmission within the pipe was impaired. This problem becomes especially noticeable when a highly volatile fuel (e.g. gasoline) is used as fuel, and the suction capacity of the fuel pump _A1 is lost and fuel is not sent to the injector system, causing the engine to malfunction. Put it away.

[Problems to be solved by the invention] On the other hand, the in-tank fuel pump a ₂ (Fig. 6)
There is no need for suction side piping, there is no need to consider suction side water head and pressure loss, and problems due to external heat rarely occur. However, even with the in-tank fuel pump _A2 , when using high outside temperature and high volatility fuel, and under the conditions that the engine is restarted immediately after stopping, the supplied fuel oil pressure will decrease immediately after the engine completely explodes. There was a problem in which the engine became malfunctioning for a while, leading to the engine stopping.

When we investigated the mechanism by which this problem occurred, we found the following.

In the overall cross section of the in-tank fuel pump _a2 shown in Fig. 7, the electric element e in the oil supply chamber d of the fuel pump _a2
At the same time as the engine is stopped, the heat accumulated during operation of the motor is transferred to the fuel in the area around the armature e, boiling and vaporizing the fuel in that area.
The vaporized fuel becomes a large amount of bubbles and pushes down the fuel oil level in the oil supply chamber d. As the amount of foam generated increases, the oil supply chamber d is filled with foam.
This bubble is cooled by the fuel in the oil supply chamber d and collapses after a while. Next, from the strainer part f,
The fuel enters again and the fuel oil level in the oil supply chamber d rises again, but the fuel in the part where it entered is evaporated again by the heat of the electric element e, so bubbles are generated again in the oil supply chamber d. do. As a result, the fuel oil level is pushed down.

When armature e loses the heat that generates bubbles,
This mechanism repeats until the above process is completed and the heat is lost.

In this way, when restarting the engine immediately after the engine has stopped, the electric element e naturally has the heat to evaporate the fuel, so the fuel delivery capacity is lost, and until the fuel delivery capacity is restored. A considerable amount of time is required.

FIG. 8 supports the above-mentioned mechanism, and shows changes in the fuel oil pressure in the discharge pipe and the fuel oil pressure in the oil supply chamber when the fuel pump is normal and when bubbles occur.

As shown in Fig. 9, the in-tank fuel pump has a discharge passage h in the upper part of the outer case g of the fuel pump _a3 , and this discharge passage h is branched to allow a portion of the fuel flowing to the discharge side. A return passage i is provided to return the fuel into the tank, and a diaphragm valve k is provided at the branching part j of the return passage i, which closes the other passage when one passage is opened, so that the fuel pressure in the oil supply chamber reaches a predetermined fuel oil pressure. There is a known ``in-tank fuel pump'' (Japanese Utility Model Publication No. 71979/1983) that attempts to return some of the fuel into the tank when the fuel exceeds the limit.

However, although it is possible to obtain a function as a leak-off passage that returns part of the fuel into the fuel tank when the return passage i is opened, it is difficult to prevent fuel bubbles from entering the discharge passage. Since the configuration is not provided, the above problem could not be solved.

[Means for solving the problem] The present invention aims to solve the above problem,
The shaft of the armature housed in the pump housing is
In an in-tank fuel pump provided through the pump housing, the cooling passage is formed in the shaft of the shaft in the axial direction thereof, and the passage is formed in the iron core of the armature. A passage in the core is opened with both ends thereof facing the outer circumferential surface of the shaft of the armature, and a communication hole is provided in the shaft to communicate the cooling passage with both open ends of the passage in the core. It is prepared.

[Operation] With the above configuration, the shaft and core of the armature are cooled, and the armature is cooled. Therefore, evaporation of fuel within the pump housing is suppressed.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 is an overall sectional view of the in-tank fuel pump according to the present invention, Fig. 2 is a detailed view of the main parts of Fig. 1, and Fig. 3 is a sectional view taken along the - line in Fig. 2. There is.

In FIG. 1, 1 is a pump housing, 2 is an upper casing, 3 is a lower casing, 6 is a casing member, 8 is a pump chamber, 9a is an impeller,
13a is a rotating shaft, 15 is a suction port, 17 is an oil supply chamber,
18a and 18b are oil feed ports, 19 is a relief valve, 20 is a leak-off passage, 21 is a discharge passage, 2
2 is a check valve, 24a is a laminated iron core, 25 is a coil, 26a is an armature, 37 is a permanent magnet, 38 is a brush, and 41 is a cooling passage.

A pressure seal 4 is provided at the end portions of the upper casing 2 and the lower casing 3 that accommodate the rotating shaft 13a.
4 are integrally fitted together. Even if some leakage occurs, this pressure seal 44 can prevent the rotation shaft 13 from leaking.
A material having a sealing ability that improves the rotational efficiency of a is selected. In other words, the in-tank fuel pump is used by being immersed in the fuel tank, and even if fuel leaks from the gap between the pressure seals 44, there is no danger.

As shown in FIG. 1, the rotating shaft 13a is provided with a cooling passage 41 passing through its shaft core. As shown in FIG. 2, the rotating shaft 13a has an extended side facing into the tank. As shown in FIG. 3, the extending portion of the rotary shaft 13a is provided with blades 45 (in the embodiment, four ) Multiple sheets are provided. Therefore, openings 46 are formed between the blades 45 to allow fuel to be actively introduced from the lower part of the cooling passage 41 and discharged to the upper part by the rotated blades 45. In addition, the rotating shaft 13 of the extended portion
At the end of a, the opening 46 is integrally formed therein and
A cap 47 of a length that does not obstruct the cap is integrally fitted. Therefore, a forced flow can be given to the fuel in the cooling passage 41, improving the heat exchange efficiency and improving the cooling performance of the armature 26a. Note that the blades 45, opening 46, and cap 47 are connected to the lower casing 3 of the rotating shaft 13a.
It may also be provided in a more extended portion. In this case, the fuel flows from above the cooling passage 41 to below.

As shown in FIG. 1, in order to cool the armature 26a more actively, an in-core passage 48 is formed in the axial direction of the laminated iron core 24a. Both end portions of the passage 48 are bent radially inward to face the clearance of the outer peripheral surface of the rotating shaft 13a. Rotating axis 1
Communication holes 49 are opened in portions 3a facing both ends of the core passage 48 to communicate the core passage 48 and the cooling passage 41, respectively.

Therefore, there is a cooling passage 41 within the iron core passage 48.
The fuel inside is now supplied, and the laminated iron core 24
a and the coil 25a can be cooled as much as possible. If the fuel inside the core passage 48 can be given a flow, the cooling performance can be further improved.
are integrally provided. The length of this plug member 51 is formed to be as short as possible. In this case, the plug member 51
It is also possible to provide a hole in the direction of the cooling passage 41, that is, a throttle hole (not shown), which has a flow passage cross section smaller than the opening diameter of the passage 48 in the core.

Note that the core passage 4 formed in the laminated iron core 24a
8 and the communication hole 49 formed in the rotating shaft 13a, the rotating shaft 13a is fixed, and the laminated iron core 24 is formed around the rotating shaft 13a.
An in-tank fuel pump configured to rotate is also effective. It is also naturally possible to provide fins 42 having a cross section as shown in FIG. 4 on the inner surface of the rotating shaft 13a to improve its cooling performance. In this case, the fins 42 are not limited to a spline shape, but may be a screw shape or an embossed shape.

[Effects of the invention] As is clear from the above explanation, the in-tank fuel pump of this invention exhibits the following excellent effects.

(1) In an in-tank fuel pump in which the shaft of an armature housed in the pump housing is provided by penetrating the pump housing, a cooling passage is formed by penetrating the shaft in the axial direction. , a passage formed in the core of the armature whose both ends are opened so as to face the outer circumferential surface of the shaft of the armature; Since the motor element is provided with communication holes provided to communicate with both open ends, it is possible to cool the motor element as much as possible, so that evaporation of fuel in the pump housing can be prevented, and the injector can be cooled as much as possible. can supply fuel to the system.

(2) The structure is simple and can be easily manufactured.

[Brief explanation of drawings]

Figure 1 is an overall sectional view of the in-tank fuel pump according to this invention, Figure 2 is a detailed view of the main parts of Figure 1,
Fig. 3 is a sectional view taken along the - line in Fig. 2, Fig. 4 is a view showing fins for improving cooling performance, Figs. 5 to 7 are schematic views showing conventional examples, and Fig. 8 is a conventional insulator. A performance diagram showing changes in fuel pressure of a tank-type fuel pump, and FIG. 9 is a schematic cross-sectional view showing a conventional example of a related conventional in-tank fuel pump. In the figure, 1 is a pump housing, 13a is a rotating shaft, 24a is a laminated iron core, 26a is an electric element, 41 is a cooling passage, and 49 is a communication hole.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In an in-tank fuel pump in which the shaft of an armature housed in the pump housing is provided so as to pass through the pump housing, an in-tank fuel pump that extends in the axial direction within the shaft of the shaft. a cooling passage formed in the above-mentioned shaft; An in-tank fuel pump characterized by comprising a communication hole provided to communicate a cooling passage with both open ends of the passage in the iron core. (2) A shaft of the armature is provided in the housing so as to be rotatable together with the armature, and the shaft supplies fuel to at least one end of the cooling passage from one side to the other. The in-tank fuel injection pump according to claim 1, which has a vane for circulation.