JP2005140027A - Pulsating diaphragm fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulsating diaphragm fuel pump having an elongated pump life without lowering pump efficiency during engine operation by reliably discharging engine oil flowing into a pulse chamber. <P>SOLUTION: In the pulsating diaphragm fuel pump 1A, a pump chamber 54 for delivering fed fuel while applying pressure thereto and the pulse chamber 55 partitioned with a pump diaphragm 52, in which pulsating pressure generated by engine operation is introduced, communicate with each other via an air hole 63. An solenoid valve 10 is installed facing a valve element 11a on an air-side opening portion of the air hole 63 for opening the air hole 63 during engine stop and closing it during engine operation in linkage with the operation of a keyswitch 12a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pulsating diaphragm fuel pump that is driven by pulsating pressure generated in a crankcase as the engine is operated and transports fuel to be supplied to the engine. In particular, the pulse chamber communicates with the atmosphere side. The present invention relates to a pulsating diaphragm fuel pump having an air hole.

  2. Description of the Related Art Pulsating diaphragm fuel pumps that have the advantage of being simple in structure and capable of being driven without mechanical loss are widely used as means for transporting fuel supplied to a two-cycle or four-cycle small gasoline engine. FIG. 3 is a longitudinal sectional view showing a well-known pulsating diaphragm fuel pump 1C that has been conventionally used. The pump chamber 54 and the pulse chamber 55 are separated by a pump diaphragm 52 on one side of the pump body 51. The other side is provided with a suction chamber 57 and a discharge chamber 58 and air chambers 59a and 59b partitioned by pulsator diaphragms 56a and 56b. A suction valve 61 a and a discharge valve 61 b are provided on the partition wall 60 that partitions the pump chamber 54, the suction chamber 57, and the discharge chamber 58 of the pump body 51.

  In this pulsating diaphragm fuel pump, the pulsating pressure generated in the crankcase is often introduced into the pulse chamber 55 by the pulsating pressure introduction path 53 along with the operation of the engine, and the pump diaphragm 52 is reciprocally displaced. The fuel in the tank is introduced from the suction chamber 57 into the pump chamber 54 through the suction valve 61a, sent to the discharge chamber 58 through the discharge valve 61b, and sent from the fuel outlet 62 to a carburetor (not shown) to be supplied to the engine. It has become.

  However, in a pulsating diaphragm fuel pump of a type that uses pulsating pressure from such a crankcase, the engine oil may flow into the pulse chamber 55 and accumulate, and the engine oil remains attached to the pump diaphragm 52. If it exists, there exists a problem of making this deteriorate early and shortening pump life.

  Therefore, for example, Japanese Patent Application Laid-Open No. 2002-98055 discloses that the engine oil that has flowed in is frequently discharged and removed by introducing a small-diameter air hole that allows the pulse chamber 55 to communicate with the atmosphere side and introducing the atmosphere into the pulse chamber 55. Proposed in the gazette. Such an air hole is indicated by reference numeral 63 in FIG. 3, and the air enters and leaves the pulse chamber 55 in conjunction with the pulsation pressure. However, since this atmospheric hole 63 is always open, the pulsation pressure in the pulse chamber 55 is lowered, the pulse width is reduced, and it is inevitable that the pump efficiency is lowered.

On the other hand, even if engine oil flows into the pulse chamber 55 during engine operation, the pump function and the pump diaphragm 52 are not immediately affected, but the engine oil remains as it is and remains attached to the pump diaphragm 52 after the engine is stopped. If it is, it will cause premature deterioration. In addition, in the above-described patent document, an example in which the pulse chamber is always communicated to the atmosphere side by an air passage and an embodiment in which a check valve is provided in the air passage are described, but the check valve is provided. The thing introduces the atmosphere into the pulse chamber at low load such as when the engine is idle, and the check valve operates so as not to be introduced at medium and high loads. Therefore, the presence of this check valve may lower the pump efficiency depending on the engine operating range, and the engine oil cannot be discharged because the air passage is closed when the engine is stopped.
JP 2002-98055 A

  The present invention is intended to solve the above-described problems, and in a pulsating diaphragm fuel pump, the engine oil flowing into the pulse chamber can be discharged to extend the pump life, and the engine operation. It is an object to prevent the pump efficiency from being lowered.

  Therefore, in the present invention, a pump chamber that pressurizes and feeds the supplied fuel and a pulse chamber that is partitioned by a pump diaphragm and into which pulsation pressure generated by engine operation is introduced are communicated with the atmosphere by an air hole. For the pulsating diaphragm fuel pump, an opening / closing means that opens when the engine is stopped and closes when the engine is operating is provided in the air hole.

  As a result, the air hole is closed during engine operation to prevent a decrease in pump efficiency, and the engine in the pulse chamber is generated by the pulsation pressure generated by the air hole being opened and the engine rotating by inertia when the engine is stopped. Since oil can be discharged together with the introduced air, in addition to stably supplying the required amount of fuel when the engine is operating, pump performance can be maintained for a long time by preventing early deterioration of the pump diaphragm. Become.

  In addition, if this opening / closing means is an electromagnetic valve that operates in conjunction with the key switch of the engine so that it opens when the engine is stopped and closes when the engine is operating, the opening and closing of the air hole is performed as the driver operates the key switch Surely done.

  Alternatively, if this opening / closing means is a negative pressure operating valve that operates in response to the intake manifold pressure of the engine and opens when the engine is stopped and closes when the engine is operating, the air hole is automatically opened and closed. be able to.

  According to the present invention, when the engine is stopped, the air hole is opened and the engine oil flowing into the pulse chamber is surely discharged, so that the pump diaphragm can be prevented from premature deterioration and the pump life can be extended. During operation, the air hole can be closed to avoid a decrease in pump efficiency.

  Referring to the drawings, an embodiment of the present invention will be described. FIG. 1 shows a first embodiment of the present invention. An electromagnetic valve 10 serving as an opening / closing means is provided at the atmosphere side opening of the atmosphere hole 63. 1 shows a provided pulsating diaphragm fuel pump 1A. The pulsating diaphragm fuel pump 1A has the same basic configuration and operation as the conventional pulsating diaphragm fuel pump 1C shown in FIG. 3 described above, and therefore will not be described in detail. The electromagnetic valve 10 is described in detail below.

  The solenoid valve 10 includes a solenoid 11 connected to a power supply circuit 12 having a power supply 12b and an engine key switch 12a, and a conical valve body 11a that is driven by the solenoid 11 to open and close the air hole 63. In the embodiment, the air hole 63 is a normally open solenoid valve that closes when the key is ON and opens when the key is OFF.

  When the key switch 12a is turned on to start the engine, the solenoid 11 is energized by the power circuit 12, and the valve body 11a is driven forward to close the air hole 63. As a result, the pulsation pressure introduced into the pulse chamber 55 is prevented from decreasing, and the required pump performance is exhibited.

  When the key switch 12a is turned OFF to stop the engine operation, the energization to the solenoid 11 is stopped, the valve body 11a is retracted, and the air hole 63 is opened. At this time, since the engine continues to rotate due to inertia, the pulsation pressure is introduced into the pulse chamber 55 during that time, while the engine oil accumulated in the pulse chamber 55 due to the introduction of air from the atmospheric hole 63 into the pulse chamber 55. Is released from the pulse pressure introduction path 53. Thus, the solenoid valve 10 reliably opens and closes the air hole 63 in conjunction with the driver's key switch operation.

  FIG. 2 shows a second embodiment of the present invention, and shows an air hole 63 portion of a pulsating diaphragm fuel pump 1B using a negative pressure operating valve 20 instead of using an electromagnetic valve as an opening / closing means. . The negative pressure chamber 20a of the negative pressure actuating valve 20 is connected to the intake manifold 70 by a connecting pipe 71, and the introduced negative pressure displaces the diaphragm 21a against the spring 21b and passes through the atmospheric hole 63. By retracting the valve shaft 22, the valve body 22 a at the tip thereof closes the air hole 63 from the pulse chamber side.

  The negative pressure operating valve 20 of the present embodiment uses pressure fluctuations generated in the intake manifold 70 as the engine is operated / stopped for opening / closing control of the air holes 63. That is, when the pressure in the intake manifold 70 becomes negative due to the engine starting, this is introduced into the negative pressure chamber 20a of the negative pressure operating valve 20 via the connection pipe 71, and the diaphragm 21a is displaced in the negative pressure chamber direction. As a result, the valve body 22a blocks the air hole 63, and thereafter, the air hole 63 is closed and the pump function is not reduced due to the decrease in the pulsation pressure.

  Then, when the engine operation is stopped, the negative pressure in the intake manifold 70 is lowered, whereby the diaphragm 21a is displaced to the opposite side by the spring 21b, and the valve body 22a opens the air hole 63. As a result, the engine oil accumulated in the pulse chamber 55 is discharged as in the pulsating diaphragm fuel pump 1A described above. As described above, the negative pressure operating valve 20 automatically and reliably opens and closes the air hole 63 by utilizing the pressure change in the intake manifold 70 due to the operation / stop of the engine.

  As described above, according to the present invention, the engine hole accumulated in the pulse chamber can be discharged by opening the air hole when the engine is stopped, and the pump diaphragm can be prevented from premature deterioration and the pump life can be extended. In addition, by closing the air hole during engine operation, the pulsation pressure is not lowered, and the required pump performance can be maintained and the required engine fuel can be supplied stably.

  When the pulsating diaphragm fuel pumps 1A and 1B shown in FIGS. 1 and 2 are actually mounted on the engine system, it is recommended to mount them with the left side in the figure facing down. This is because the pulse pressure introduction path 53 is located below the pulse chamber 55, so that even if engine oil adheres to the pump diaphragm 52, removal is easy.

1 is a longitudinal sectional view showing a first embodiment of the present invention. The longitudinal cross-sectional view which shows the 2nd Embodiment of this invention. The longitudinal cross-sectional view which shows a prior art example.

Explanation of symbols

1A, 1B Pulsating diaphragm fuel pump, 10 Solenoid valve, 11 Solenoid, 11a, 22a Valve body, 12 Power supply circuit, 12a Key switch, 20 Negative pressure operating valve, 20a Negative pressure chamber, 21a Diaphragm, 52 Pump diaphragm, 54 Pump Chamber, 55 pulse chamber, 63 air holes, 70 intake manifold

Claims (3)

In a pulsating diaphragm fuel pump in which a pump chamber that pressurizes and feeds fuel that has been pumped in and a pulse chamber that is partitioned by a pump diaphragm and into which pulsation pressure generated by engine operation is introduced is communicated with the atmosphere by an air hole ,
An opening / closing means that opens when the engine is stopped and closes when the engine is operating is provided in the air hole.
A pulsating diaphragm fuel pump characterized by that.   2. The pulsating diaphragm fuel pump according to claim 1, wherein the opening / closing means is an electromagnetic valve that operates so as to open when the engine is stopped and close when the engine is operating in conjunction with a key switch of the engine. 2. The pulsating diaphragm fuel pump according to claim 1, wherein the opening / closing means is a negative pressure operating valve that operates so as to open when the engine is stopped and close when the engine is operating in response to an intake manifold pressure of the engine.

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