JP2003003962A - Diaphragm pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of reliability particularly at low temperature on a condition reducing assembly man-hours and troublesomeness by a small number of part items. SOLUTION: This diaphragm pump comprises a valve seat unit 22 protruding a suction valve 21 into a pump chamber 6 and a valve element 25 formed in a part mutually opposed to the valve seat unit 22 of a pump diaphragm 3 and comprises a valve seat unit 27 protruding a delivery valve 26 into a delivery chamber 14 and a valve element 30 formed in a part mutually opposed to the valve seat unit 27 of a pulsator diaphragm 10, to reduce the number of part items. The pulsator diaphragm 10 is made in hardness lower than the diaphragm pump 3, and flexibility is maintained at low temperature time, so as to obtain a normal pump function.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine, mainly an engine, mainly driven by pressure pulsation generated in a shaft that rotates with the operation of an engine or in a crankcase or an intake manifold. The present invention relates to a diaphragm pump used for supplying fuel to a two-cycle engine. 2. Description of the Related Art A mechanical, pulsating or electromagnetic diaphragm is used as a means for supplying fuel to a two-cycle or four-cycle small gasoline engine which is a power source of an agricultural machine, an outboard motor, a light vehicle, or the like. Pumps are widely used. FIG. 3 is a cross-sectional view showing an example of a conventional general pulsating diaphragm pump. A pump diaphragm 52 and a cover 53 are overlapped on one surface of a main body 51 and provided on the main body 51. Pump diaphragm 5
The cavity covered by 2 forms a pump chamber 54, and the inside of the cover body 53 forms a pulse chamber 55 in which a diaphragm spring 57 is housed. A pulsator diaphragm 58 and a cap 59 are overlapped on another surface of the main body 51. Two dents provided in the main body 51 and covered by the pulsator diaphragm 58 define a suction chamber 60 and a discharge chamber 62. The interior of the cap 59 is formed in the air chamber 6 communicating with the atmosphere.
4 are formed. Further, a suction valve 65 is provided between the suction chamber 60 and the pump chamber 54, and a discharge valve 67 is provided between the pump chamber 54 and the discharge chamber 62. A pressure pulsation of air generated in the crankcase or the intake manifold with the operation of the engine, generally a pressure pulsation generated in the crankcase, is transmitted from the pulse inlet 56 provided in the cover 53 to the pulse chamber 55. After being introduced, the pump diaphragm 52 is reciprocally displaced, and fuel in a fuel tank (not shown) is supplied from the fuel inlet 61 to the suction chamber 60,
The fuel is sent to the fuel outlet 63 via the suction valve 65, the pump chamber 54, the discharge valve 67, and the discharge chamber 62, and supplied to the engine from a carburetor (not shown). In the suction chamber 60 and the discharge chamber 62, the pulsation of the fuel is smoothed by the pulsator diaphragm 58, so that the suction efficiency and the discharge efficiency are improved. The suction valve 65 and the discharge valve 67 are check valves installed on the bottom wall of the main body 51 that divides the pump chamber 54, the suction chamber 60, and the discharge chamber 62. The valve bodies 66 and 68 for opening and closing the valve seats respectively connecting the suction chamber 60 and the pump chamber 54 are the minimum necessary parts.
In order to reliably close the valve, a non-return valve formed by using a component such as a valve closing spring acting on a valve body and a spring receiver for holding the valve closing spring is also often used. Such a suction valve 6
5. The discharge valve 67 is not limited to the pulsating type, but is also indispensable to a mechanical type and an electromagnetic type. For this reason, the number of parts constituting the pump is large, and especially the constituent parts of the check valve are extremely small, so that the assembly requires many man-hours and is troublesome, and a pump having a reliable pump function is inexpensive. It is difficult to respond to the demand to purchase the product. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a small number of parts, thus reducing the man-hour and trouble of assembling, and making it possible to provide at low cost. It is an object of the present invention to provide a diaphragm pump that does not impair the reliability of the pump function, particularly at low temperatures. SUMMARY OF THE INVENTION The present invention provides a fuel suction chamber and discharge chamber, a pump chamber, and a pressure generated in a shaft that rotates with the operation of an engine, or in a crankcase or an intake manifold. The present invention relates to a diaphragm pump having a pump diaphragm which reciprocates by pulsation to change the volume of a pump chamber and a pulsator diaphragm for smoothing pulsation of fuel generated in a suction chamber and a discharge chamber. The above problem caused by the above was solved as follows. That is, first, regarding the suction valve, the valve seat is projected into the inside of the pump chamber, and the valve is formed of a portion facing the valve seat of the pump diaphragm.
As for the discharge valve, the valve seat was made to protrude into the discharge chamber, and the valve was made of a portion facing the valve seat of the pulsator diaphragm. The pump diaphragm moves away from the seat surface, which is the end surface of the valve seat body of the suction valve, in a suction stroke in which the pump chamber is displaced in a direction to increase the volume of the pump chamber. Contact to sit. On the other hand, the pulsator diaphragm contacts and seats on the seat surface which is the end surface of the valve seat body of the discharge valve during the suction process, but separates from the seat surface during the discharge stroke. In this way, by using the two diaphragms that have been conventionally provided as functional parts as the respective valve elements of the suction valve and the discharge valve, the number of parts is reduced, and thus the number of assembly steps and labor are reduced. It can be provided at low cost. Second, the pulsator diaphragm uses a diaphragm having a lower hardness than the pump diaphragm. The pump diaphragm is forcibly driven by rotation of the shaft and pressure pulsation accompanying the operation of the engine.
The pulsator diaphragm is driven by a pressure change in the pump chamber due to the displacement of the pump diaphragm. On the other hand, the diaphragm is made of rubber, and has a property of increasing hardness when the temperature decreases, and the movement becomes slow at a low temperature. Regarding the pump diaphragm, even if a high-hardness pump is used in consideration of durability, the movement is not slowed down even if it is affected by temperature because it is forcibly driven as described above, but the pump diaphragm is indirectly driven by the movement of the pump diaphragm. The movement of the pulsator diaphragm is slowed down by the influence of the temperature, and the discharge valve is poorly opened or closed, thereby decreasing the fuel flow rate. In the present invention, the pulsator diaphragm is made to have a lower hardness than the pump diaphragm in consideration of increasing the hardness at a low temperature, and the hardness is such that a required movement can be performed even when the hardness is increased at a low temperature. This makes it possible not to impair the reliability of the pump function, especially at low temperatures. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a pulsating diaphragm pump with reference to FIG.
The pump diaphragm 3 and the cover body 5 are overlapped on one surface of the above, and a recess provided in the main body 1 and covered by the pump diaphragm 3 forms a pump chamber 6. The cover body 5 has a pulse inlet 7 connected to an engine crankcase or an intake manifold,
The inside thereof forms a pulse chamber 8 and accommodates a diaphragm spring 9. A pulsator diaphragm 10 and a cap 11 are overlapped on another surface parallel to the above-mentioned surface of the main body 1, and two depressions provided in the main body 1 and covered by the pulsator diaphragm 10 are suction chambers. The suction chamber 12 has a fuel inlet 13 connected to a fuel tank, and the discharge chamber 14 has a fuel outlet 15 connected to a carburetor. The interior of the cap 11 is divided into two spaces corresponding to the suction chamber 12 and the discharge chamber 14, respectively.
6 are formed. A pump chamber 6 and a suction chamber 12, which are open to two surfaces of the main body 1 and have recesses provided back to back, are formed.
A cylindrical valve seat 22 protrudes into the pump chamber 6 at a portion of the suction chamber 12 on the bottom wall 2 that defines the discharge chamber 14. The valve seat body 22 has a valve seat port 23 which is a passage connecting the suction chamber 12 and the pump chamber 6, and has an end face on the pump chamber 6 side as a seat surface 24. The seat surface 24 is located at a position close to the pump diaphragm 3 so that the reciprocatingly displaced pump diaphragm 3 contacts at an appropriate position in the middle of the displacement stroke. A portion of the pump diaphragm 3 facing the seat surface 24 is a valve seat. Mouth 2
It functions as a valve body 25 that opens and closes 3. The valve seat body 22,
The valve seat 23, the seat surface 24, and the valve body 25 are connected to the suction valve 21.
Is composed. On the other hand, a cylindrical valve seat 27 is provided in the discharge chamber 14 on the bottom wall 2 so as to protrude into the discharge chamber 14. The valve seat body 27 has a valve seat port 28 which is a passage connecting the pump chamber 6 and the discharge chamber 14, and has an end surface on the discharge chamber 14 side as a seat surface 29. The seat surface 29 is located at a position where the pulsator diaphragm 10 comes into contact with the inoperative position when the engine is stopped or an intermediate suitable position during the reciprocating displacement stroke, in this embodiment, the inoperative position. The part opposite to serves as a valve body 30 for opening and closing the valve seat opening 28. The valve seat 27, the valve seat 28, the seat surface 29 and the valve 30 constitute the discharge valve 26. Diaphragm retainer 4 superposed on pump diaphragm 3 and receiving diaphragm spring 9
May be installed concentrically with the pump diaphragm 3 as in the prior art, but in the present embodiment, it is installed eccentrically toward the discharge chamber 14, and when the suction valve 21 is closed, the diaphragm retainer 4 is attached to the seat surface 24. Only the flexible pump diaphragm 3, which does not overlap, overlaps the seat surface 24 so that the valve can be completely closed. In this case, the pump diaphragm 3 comes into contact with and separates from the seat surface 24 as a valve body 25 at a portion not limited by the stroke of the diaphragm spring 9, and the suction valve 21 is greatly opened to increase the fuel flow rate. It is possible to do. Further, since the pump diaphragm 3 is forcibly driven by pressure pulsation and the load of the diaphragm spring 9 always acts, a pump diaphragm 3 having sufficient hardness is used in consideration of durability. On the other hand, the pulsator diaphragm 10 is of a hardness lower than that of the pump diaphragm 3 in consideration of the fact that the movement slows down due to the increase in hardness at low temperatures. In this embodiment, when the pressure pulsation generated in the crankcase due to the operation of the engine is introduced into the pulse chamber 8 through the pulse introduction port 7, the engine piston moves to the top dead center. Due to the negative pressure, the pump diaphragm 3 is displaced toward the pulse chamber 8 to generate a negative pressure in the pump chamber 6 and the valve body 25 separates from the seat surface 24. As a result, the fuel in the suction chamber 12 flows into the pump chamber 6, while the pulsator diaphragm 10 is sucked by the negative pressure of the pump chamber 6, bringing the valve body 30 into close contact with the seat surface 29 and closing the discharge valve 26. Set to valve state. When the pump diaphragm 3 is displaced toward the pump chamber 6 by the positive pressure generated by the movement of the engine piston to the bottom dead center, the fuel in the pump chamber 6 is pressurized and the pulsator diaphragm 10 is moved to the air chamber 16. And the valve body 30 moves away from the seat surface 29 to send the fuel in the pump chamber 6 from the discharge chamber 14 to the fuel outlet 15. On the other hand, the valve body 25 of the pump diaphragm 3 is in close contact with the seat surface 24 to close the suction valve 21. By repeating the above, the fuel is supplied to the suction chamber 12.
From the pump chamber 6 to the discharge chamber 14. At this time, the suction valve 21 and the discharge valve 26 have the valve bodies 25 and 30 formed by the pump diaphragm 3 and the pulsator diaphragm 10, which are functional parts of the pump. The amount of displacement of the two diaphragms 3, 10 in particular, the portions of the valve bodies 25, 30 and the position of the seat surfaces 24, 29 allow a reliable opening / closing operation and a large fuel flow rate to be obtained. FIG. 2 is a graph showing the results of a test conducted on the influence of temperature on the operation of the pulsator diaphragm 10 using the pump prototype having the structure shown in FIG. 1, wherein the rubber hardness is Hs = 50 and Hs = The flow rate of the fuel delivered from the fuel outlet 15 was measured while changing the temperature of each of the two types of diaphragms. Curve A shows the case where a pulsator diaphragm having a rubber hardness Hs = 50 was used.
A substantially constant fuel flow rate of about 20 (L / h) is maintained at 5 to -17 (° C). This indicates that the discharge valve 26 is opening and closing normally. The B curve shows the case where a pulsator diaphragm having a rubber hardness Hs = 60 was used. In the temperature range of 27 to -16 (° C.) where the measurement was performed, the fuel flow rate decreased proportionally with the temperature drop, and −4.5.
The temperature decreased rapidly below ℃ and became zero at below -8.5 ℃. This indicates that the discharge valve 26 is not operating at a low temperature. Incidentally, an endurance test was conducted in which the pump diaphragm 3 was driven by pressure pulsation in the crankcase using two kinds of diaphragms having rubber hardness Hs = 50 and Hs = 60. It was confirmed that those which operated normally but had Hs = 50 were broken during the test and had poor durability. From these test results, the pump diaphragm 3 having a certain hardness is used in consideration of durability, and the pulsator diaphragm 10 is low in consideration of not losing flexibility at low temperatures. It is understood that the use of a material having a hardness is important for achieving the purpose of not impairing the reliability of the pump function at low temperatures. In the embodiment shown in FIG. 1, the valve 30 is in contact with the seat surface 29 at the inoperative position of the pulsator diaphragm 10 when the engine is stopped. 30 may be separated from the seat surface 29. In this case as well, if the flexibility is lost due to the temperature drop, the discharge valve 26 remains open, causing the fuel to flow backward during the pump suction stroke and greatly reducing the fuel flow rate. Use is necessary to achieve the objects of the present invention. As described above, according to the present invention, the valve elements of the suction valve and the discharge valve are formed by the pump diaphragm and the pulsator diaphragm, which are functional parts of the pump itself. Man-hours and troubles are reduced, and it is possible to provide at low cost. Further, by making the pulsator diaphragm lower in hardness than the pump diaphragm, the opening and closing operation of the discharge valve at a low temperature is normally maintained, and high reliability for the pump function is provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention. FIG. 2 is a graph of a test result showing a relationship between a temperature and a fuel flow rate. FIG. 3 is a longitudinal sectional view showing a conventional example. [Description of Signs] 1 pump diaphragm, 6 pump chamber, 10 pulsator diaphragm, 12 suction chamber, 14 discharge chamber, 21
Suction valve, 22, 27 valve seat, 25, 30 valve, 2
6 discharge valve,

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F04B 53/10 F16J 3/02 A F16J 3/02 F04B 21/02 G F-term (Reference) 3H071 AA07 BB01 CC25 CC31 CC32 DD04 DD32 DD35 DD51 3H077 AA03 BB01 CC02 CC07 CC12 DD07 DD14 EE04 EE34 EE35 FF03 FF08 FF14 FF22 FF45 3J045 AA09 AA14 BA02 CA20 EA10

Claims (1)

Claims: 1. A diaphragm pump having a pulsator diaphragm for smoothing fuel pulsation in a suction chamber and a discharge chamber, wherein the suction valve for communicating and shutting off the suction chamber and the pump chamber is provided. The pump chamber includes a valve body protruding into a pump chamber, and a valve body including a portion facing the valve seat body of a pump diaphragm that reciprocates and changes the volume of the pump chamber. A discharge valve that communicates with and shuts off the discharge chamber is provided with a valve seat made of a portion facing the valve seat of the pulsator diaphragm, and a valve seat that protrudes into the inside of the discharge chamber, The pulsator diaphragm is made of a diaphragm having a lower hardness than the pump diaphragm.