Mixed liquid pump

Abstract

To provide a liquid mixture pump capable of causing liquid mixed at an appropriate ratio to flow out.SOLUTION: External pulsation is received in a pulse chamber and converted into volume fluctuation of a mixing pump chamber by using a diaphragm. In accordance with the volume fluctuation of the mixing pump chamber, first liquid is supplied from a first liquid supply passage and second liquid is supplied from a second liquid supply passage to the single mixing pump chamber. A diffusion port, a diffusion chamber and a second liquid restriction mechanism are disposed between the mixing pump chamber and a second liquid inlet passage. The second liquid of which amount is restricted by the second liquid restriction mechanism flows into the diffusion chamber, and the second liquid is diffused in the first liquid in the diffusion chamber. A liquid mixture in which the second liquid is diffused flows into the mixing pump chamber from the diffusion port. Then, the liquid mixture in which the second liquid is diffused is further mixed with the first liquid in the mixing pump chamber, and the liquid mixture mixed in the mixing pump chamber is caused to flow out from a liquid mixture outlet passage to outside.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present disclosure relates to a mixed - liquid pump that sucks and mixes two kinds of liquids and discharges the mixed liquid. The mixed - liquid pump of the present disclosure is suitable for use, for example, in mixing gasoline and oil in a two - cycle engine.

Background Art

[0002] As a mixed - liquid pump, a pump that supplies gasoline and oil to a two - cycle engine is described, for example, in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] One aspect of this disclosure includes a first liquid inlet passage (162) through which a first liquid flows into the mixing pump chamber, an inlet check valve (180) positioned in the first inlet passage which allows only the flow of the first liquid into the mixing pump chamber and prevents backflow from the mixing pump chamber, and a second liquid supply passage (163) which supplies a second liquid to the mixing pump chamber. One aspect of this disclosure is a liquid mixing pump in which a first liquid and a second liquid are supplied to a single mixing pump chamber.

[0008] One of the present disclosures comprises a diffusion port (161) formed at the end of the second liquid supply passage on the mixing pump chamber side, having an opening area smaller than the opening area of ​​the first liquid inlet passage; a diffusion chamber (164) formed on the second liquid supply passage side of the diffusion port for diffusing the second liquid into the first liquid; and a second liquid limiting mechanism (130) arranged on the second liquid supply passage side of the diffusion chamber for limiting the amount of the second liquid flowing from the second liquid supply passage to the diffusion chamber. In one of the present disclosures, the diffusion port, the diffusion chamber, and the second liquid limiting mechanism are arranged between the mixing pump chamber and the second liquid inlet passage. The amount of the second liquid limited by the second liquid limiting mechanism flows into the diffusion chamber, and the second liquid diffuses into the first liquid within the diffusion chamber. The mixed liquid in which the second liquid has diffused then flows into the mixing pump chamber from the diffusion port.

[0009] One of the present disclosures includes a mixed liquid outlet passage (165) through which a mixture of a first liquid and a second liquid flows out of a mixing pump chamber, and an outlet check valve (181) located in this mixed liquid outlet passage that allows only the flow of the mixed liquid out of the mixing pump chamber and prevents backflow into the mixing pump chamber. In one of the present disclosures, a mixture of the first liquid and the second liquid mixed in the mixing pump chamber is discharged.

[0010] Except as otherwise provided, the second liquid limiting mechanism comprises a second liquid limiting passage (131) formed between a diffusion chamber and a second liquid supply passage, and a second liquid limiting piston (132) positioned within the second liquid limiting passage with a small gap between them and capable of reciprocating within the passage. The pressure in the diffusion chamber fluctuates in accordance with the volume fluctuations of the mixing pump chamber, and the second liquid limiting piston reciprocates in response to the pressure fluctuations in the diffusion chamber. Oil from the second liquid supply passage is supplied to the diffusion chamber through the small gap between the second liquid limiting piston and the second liquid limiting passage in accordance with the reciprocating movement of the second liquid limiting piston. Except as otherwise provided, the supply of the second liquid can be limited by utilizing the small gap between the second liquid limiting piston and the second liquid limiting passage.

[0011] A further second liquid limiting mechanism of this disclosure comprises a limiting mechanism support spring (133) that supports the reciprocating movement of a second liquid limiting piston. The limiting mechanism support spring facilitates the reciprocating movement of the second liquid limiting piston.

[0012] In other disclosures, the opening area of ​​the diffusion port is made smaller than 20 percent of the opening area of ​​the first liquid inlet passage. The liquid flowing into the mixing pump chamber from the diffusion port is a mixture formed when the second liquid diffuses into the first liquid in the diffusion chamber. By making the opening area smaller than 20 percent of the opening area of ​​the first liquid inlet passage, the amount of the mixture flowing in from the diffusion port can be reduced. As a result, the amount of the second liquid flowing into the mixing pump chamber can be reduced to about 2 percent of the total.

[0013] In yet another disclosure, the first liquid is gasoline and the second liquid is oil. The pulse chamber communicates with the engine's crankcase and receives pressure pulsations from within the crankcase. The mixture outlet passage supplies the engine with a mixture of gasoline and oil. Yet another mixture pump in this disclosure is used to supply a mixture of gasoline and oil to a two-stroke engine.

[0014] In other disclosures, diaphragm support springs (112, 152) are provided in the pulse chamber and the mixing pump chamber to support the diaphragm. By providing the diaphragm support springs, the reciprocating motion of the diaphragm can be stabilized.

[0015] In yet another aspect of this disclosure, an auxiliary diaphragm (190) is placed on a surface forming the mixing pump chamber, other than the surface on which the diaphragm is placed. The auxiliary diaphragm is subjected to the pressure of the mixing pump chamber on one side and atmospheric pressure on the other side. Furthermore, the auxiliary diaphragm is displaced in accordance with pressure fluctuations in the mixing pump chamber. By placing the auxiliary diaphragm, the pressure in the mixing pump chamber is maintained at atmospheric pressure, and the volume of the mixing pump chamber is made more responsive to fluctuations.

[0016] In other aspects of this disclosure, the auxiliary diaphragm is positioned parallel to the diaphragm. This makes it easier to position the auxiliary diaphragm. Furthermore, the auxiliary diaphragm displaces in accordance with the displacement of the diaphragm. That is, the auxiliary diaphragm is easily displaced in response to the displacement of the diaphragm. This allows for a more efficient function of easily changing the volume of the mixing pump chamber.

[0017] In other disclosures, the diaphragm has a disc shape with a bent portion (174), while the auxiliary diaphragm has a flat, circular shape without a bent portion. Therefore, the displacement of the auxiliary diaphragm is smaller than that of the diaphragm. The auxiliary diaphragm is intended to assist the diaphragm in bringing the pressure in the mixing pump chamber to atmospheric pressure and compensating for volume fluctuations. Therefore, the displacement of the auxiliary diaphragm is smaller than that of the diaphragm.

[0018] In still other aspects of the present disclosure, the inlet check valve and the outlet check valve include a check valve seat (184), a check valve body (182, 185, 187) that opens and closes the check valve seat, and a check valve spring (183) that biases the check valve body toward the check valve seat side. Even when the volume fluctuation of the mixing pump chamber is small and the flow rate of the flowing fluid is small, the inlet check valve and the outlet check valve can surely flow the fluid downstream while preventing backflow.

Brief Description of the Drawings

[0019] [Figure 1] It is a cross-sectional view of an embodiment of the mixed liquid pump of the present disclosure. [Figure 2] It is a cross-sectional view of the state where the mixed liquid pump shown in FIG. 1 is assembled to the engine. [Figure 3] It is a cross-sectional view showing the oil restriction mechanism of the mixed liquid pump shown in FIG. 1. [Figure 4] It is a cross-sectional view showing the inlet check valve of the mixed liquid pump shown in FIG. 1. [Figure 5] It is a cross-sectional view showing another example of the inlet check valve. [Figure 6] It is a cross-sectional view showing another example of the inlet check valve. [Figure 7] It is a cross-sectional view showing another example of the inlet check valve. [Figure 8] It is a cross-sectional view showing another example of the mixed liquid pump. [Figure 9] It is a cross-sectional view of the state where the mixed liquid pump shown in FIG. 8 is assembled to the engine. [Figure 10] It is a perspective view of another embodiment of the mixed liquid pump of the present disclosure. [Figure 11] It is a plan view of the mixed liquid pump shown in FIG. 10. [Figure 12] It is a cross-sectional view taken along line XII-XII of FIG. 11.

Embodiments for Carrying Out the Invention

[0020] The mixed liquid pump 100 of this disclosure will be described with reference to Figure 1. The mixed liquid pump 100 comprises an upper housing 110 and a lower housing 150. Note that the arrangement of the upper housing 110 and the lower housing 150 in Figure 1 is as shown and does not indicate the top and bottom orientation in actual use. Similarly, the notations of "upper" and "lower" hereafter do not indicate the top and bottom orientation in use. Both the upper housing 110 and the lower housing 150 are formed by injection molding of a resin with excellent gasoline resistance. For example, polyacetal resin is used as the resin material.

[0021] A diaphragm 170 is positioned between the upper housing 110 and the lower housing 150. The diaphragm 170 is made of a flexible material, such as nitrile rubber or fluororubber. The outer circumference 171 of the diaphragm 170 is sandwiched between the upper housing 110 and the lower housing 150. The central part 172 of the diaphragm 170 is sandwiched between the upper plate 111 and the lower plate 151. The upper plate 111 and the lower plate 151 are also made of resin, such as polyacetal resin, which is injection molded. The area between the outer circumference 171 and the central part 172 of the diaphragm 170 is bent to form a bent portion 174. The diaphragm 170 has a disc shape with the bent portion 174, and the bent portion 174 makes it easily displaceable in the vertical direction of Figure 1.

[0022] A pulse chamber 120 is formed between the diaphragm 170 and the upper housing 110. The pulse chamber 120 communicates with the crankcase 201 of the engine 200 shown in Figure 2 via a pressure introduction passage 1121 and a pressure introduction pipe 1120. A pressure introduction passage locking portion 1121a is formed on the outer circumference of the pressure introduction passage 1121 to prevent the pressure introduction pipe 1120, which connects to the crankcase 201, from coming loose.

[0023] Here, we will briefly explain the structure of the 2-stroke engine 200. In Figure 2, the piston 202 reciprocates within the cylinder block 203, and this reciprocating motion is transmitted to the crankshaft 205 via the connecting rod 204. At this time, the reciprocating motion of the piston 202 is converted into rotational motion of the crankshaft 205, which rotates within the crank chamber 201. 2050 is a web, and when the crankshaft 205 rotates, this web 2050 balances the rotation with that of the piston 202.

[0024] An intake passage 206 opens into the crankcase 201, through which intake air filtered by an air filter (not shown) flows in. An intake valve 207 is positioned in the intake passage 206 to prevent intake air from flowing back from the crankcase 201 into the intake passage 206. Downstream of the intake valve 207 in the intake passage 206, gasoline mixed with oil is also supplied from the fuel mixture pump 100 in this example. More specifically, the gasoline mixed with oil by the fuel mixture pump 100 is injected into the cylinder head 209 by the injector 220.

[0025] Figure 2 shows the exhaust and scavenging strokes of a two-stroke engine 200 with the piston 202 moved downwards in the figure. Intake air drawn into the crankcase 201 is supplied to the cylinder head 209 through the scavenging passage 208 during the scavenging stroke. The intake air supplied to the cylinder head 209 is compressed along with the gasoline and oil mixture injected from the injector 220 during the compression stroke as the piston 202 rises. The compressed intake air and gasoline are burned by ignition from the spark plug 210, and their volume expands. This volume expansion pushes the piston 202 down, resulting in the state shown in Figure 2. In this state, exhaust gas is discharged from the exhaust port 211 into the exhaust passage 212. An exhaust valve 213 is located in the exhaust passage 212 to prevent backflow of exhaust gas.

[0026] In a two-stroke engine 200, the compression stroke, expansion stroke, and exhaust scavenging stroke are repeated, causing the piston 202 to reciprocate within the cylinder block 203. This reciprocating motion of the piston 202 causes the pressure in the crankcase 201 to pulsate. Therefore, the pressure in the pulse chamber 120, which is at the same pressure as the crankcase 201, also pulsates. The pulsation of the crankcase 201 varies depending on the size of the engine 200, but for an engine 200 with a volume of approximately 30 to 90 cc (cubic centimeters), the pressure fluctuation is at least about 5 kilopascals. The pressure fluctuations of the engine 200 will be discussed later.

[0027] A mixing pump chamber 160 is formed on the opposite side of the pulse chamber 120 and the diaphragm 170. That is, the mixing pump chamber 160 is formed in the lower housing 150, and the upper surface of the surface forming the mixing pump chamber 160 is closed by the diaphragm 170. The internal pressure of the pulse chamber 120 fluctuates in accordance with the pulsation of the crank chamber 201. On the other hand, the pressure inside the mixing pump chamber 160 is approximately atmospheric pressure and does not fluctuate significantly. Therefore, the diaphragm 170 reciprocates between the pulse chamber 120 and the mixing pump chamber 160 in accordance with the pressure fluctuations in the pulse chamber 120. As described above, the diaphragm 170 is provided with a bent portion 174 to facilitate reciprocating movement. The diaphragm 170 is supported vertically by an upper diaphragm support spring 112 and a lower diaphragm support spring 152. Therefore, the reciprocating movement of the diaphragm 170 is stabilized by the upper diaphragm support spring 112 and the lower diaphragm support spring 152. In this disclosure, the diaphragm support spring refers collectively to the upper diaphragm support spring 112 and the lower diaphragm support spring 152.

[0028] In this example, both the pulse chamber 120 and the mixing pump chamber 160 are circular with a diameter of approximately 15 to 20 millimeters. As mentioned above, the diaphragm 170 is also disc-shaped, and the diaphragm 170 moves back and forth between the pulse chamber 120 and the mixing pump chamber 160 by approximately 2 to 4 millimeters.

[0029] The lower end of the upper diaphragm support spring 112 is held by the upper shoulder portion 113 formed on the upper plate 111. The upper end of the upper diaphragm support spring 112 abuts against the upper receiving portion 114 formed on the upper housing 110. Overall, the outer circumference of the upper diaphragm support spring 112 is held by the retaining hole 115 formed on the upper housing 110, and the inner circumference is held by the upper retaining projection 116 formed on the upper housing 110.

[0030] The lower diaphragm support spring 152 is similar. The upper end of the lower diaphragm support spring 152 is held by a lower shoulder portion 153 formed on the lower plate 151. The lower end of the lower diaphragm support spring 152 abuts against a lower receiving portion 154 formed on the lower housing 150. The lower diaphragm support spring 152 as a whole is positioned in the mixing pump chamber 160 formed in the lower housing 150, and its inner circumference is held by a lower holding projection 155 formed on the lower housing 150. A communication passage 156 connecting the diffusion port 161 (described later) and the mixing pump chamber 160 is formed in the lower holding projection 155.

[0031] As described above, the pressure fluctuations within the pulse chamber 120 are not large, so the compressive force of both the upper diaphragm support spring 112 and the lower diaphragm support spring 152 is set to a small value. For example, the set pressure is 0.5 Newtons or less. Furthermore, the upper diaphragm support spring 112 and the lower diaphragm support spring 152 have the same compressive force. Therefore, the behavior of the diaphragm 170 is stabilized by the upper diaphragm support spring 112 and the lower diaphragm support spring 152, but the reciprocating movement of the diaphragm 170 is not hindered.

[0032] The upper housing 110 and the lower housing 150 have gasoline supply passages 162 formed therein for supplying gasoline, which is the first liquid, to the mixing pump chamber 160. The first liquid supply passage in this disclosure corresponds to the gasoline supply passage 162. Of the gasoline supply passage 162, the upper gasoline supply passage portion 117 formed in the upper housing 110 has an upper gasoline supply passage locking portion 117a formed on its outer circumference to prevent the fuel pipe from coming off. Of the gasoline supply passage 162, the lower gasoline supply passage 157 formed in the lower housing 150 is L-shaped. The opening of this lower gasoline supply passage 157 is closed by a lower gasoline supply passage plug 158. The lower gasoline supply passage plug 158 is screwed to the lower housing 150.

[0033] An inlet check valve 180 is located in the lower gasoline supply passage 157. As shown in Figure 4, the inlet check valve 180 is a duckbill check valve made of a flexible material such as nitrile rubber. The inlet check valve 180 allows gasoline to flow only towards the mixing pump chamber 160 through the gasoline supply passage 162, preventing backflow of gasoline. In this example, the inlet check valve 180 is sandwiched between the upper housing 110 and the lower housing 150.

[0034] An oil supply passage 163 is formed in the lower housing 150 to supply oil, which is a second liquid, to the mixing pump chamber 160. The second liquid supply passage in this disclosure corresponds to this oil supply passage 163. The oil supply passage 163 also has an oil supply passage locking portion 163a formed on its outer circumference to prevent the oil pipe from coming out. The oil supply passage 163 is formed in an L shape, and its opening is closed by an oil supply passage plug 159. This oil supply passage plug 159 is also screwed to the lower housing 150, similar to the lower gasoline supply passage plug 158.

[0035] The lower housing 150 has a diffusion chamber 164 formed between the diffusion port 161 and the oil supply passage 163. The diffusion port 161 is a pore with a diameter of about 0.2 millimeters, as shown in Figure 3. The diffusion chamber 164 is a small chamber with a volume of about 2 cubic millimeters. The lower housing 150 also has an oil limiting mechanism 130 positioned between the diffusion chamber 164 and the oil supply passage 163. This oil limiting mechanism 130 corresponds to the second liquid limiting mechanism of this disclosure.

[0036] The oil restriction mechanism 130 includes an oil restriction passage 131 formed between the oil supply passage 163 and the diffusion chamber 164 of the lower housing 150. The oil restriction mechanism 130 also includes an oil restriction piston 132 positioned within the oil restriction passage 131 with a small gap between them. The small gap is sufficient to allow the oil restriction piston 132 to move smoothly through the oil restriction passage 131, for example, about 0.05 millimeters. These oil restriction passage 131 and oil restriction piston 132 constitute the second of the present disclosure. liquid Body restriction passage and 2 liquid It is compatible with body-restricting pistons.

[0037] The oil limiting mechanism 130 also includes a limiting mechanism support spring 133 that presses the oil limiting piston 132 toward the diffusion chamber 164. The upper end of the limiting mechanism support spring 133 engages with a piston locking portion 134 formed on the oil limiting piston 132. The lower end of the limiting mechanism support spring 133 engages with a plug locking portion 135 formed on the oil supply passage plug 159. In this way, the limiting mechanism support spring 133 supports the reciprocating movement of the oil limiting piston 132.

[0038] In response to volume fluctuations in the mixing pump chamber 160, the oil-restricting piston 132 reciprocates within the oil-restricting passage 131. This reciprocating motion of the oil-restricting piston 132 causes the oil interposed between the oil-restricting piston 132 and the oil-restricting passage 131 to flow into the diffusion chamber 164. In other words, the amount of oil that flows into the diffusion chamber 164 is limited by the amount of oil-restricting mechanism 130.

[0039] Furthermore, in accordance with the volume fluctuations of the mixing pump chamber 160, gasoline that has flowed into the mixing pump chamber 160 also flows into the diffusion chamber 164 via the diffusion port 161. Therefore, the amount of oil limited by the oil limiting mechanism 130 will diffuse into the gasoline within the diffusion chamber 164. For example, the mixing ratio of gasoline to oil in the diffusion chamber 164 will be approximately 10-40%. The oil mixing ratio in the diffusion chamber 164 is higher than the oil mixing ratio in the mixing pump chamber 160. However, the oil mixing ratio in the diffusion chamber 164 is determined by many factors, such as the volume of the mixing pump chamber 160, the volume of the diffusion chamber 164, and the volume fluctuations of the mixing pump chamber 160 due to the reciprocating movement of the diaphragm 170. Therefore, the above figure of approximately 10-40% is just one example of the oil mixing ratio.

[0040] Volume fluctuations in the mixing pump chamber 160 result in not only liquid flow from the mixing pump chamber 160 to the diffusion chamber 164, but also liquid flow from the diffusion chamber 164 to the mixing pump chamber 160. Therefore, the gasoline and oil mixture formed in the diffusion chamber 164 flows into the mixing pump chamber 160 through the diffusion port 161. The oil component of the incoming mixture then diffuses further within the mixing pump chamber 160.

[0041] As a result, the liquid in the mixing pump chamber 160 will be a mixture consisting mostly of gasoline with an oil content of about 2 percent. In other words, the opening area of ​​the diffusion port 161 and the opening area of ​​the gasoline supply passage 162 are determined so that the oil content in the mixture is about 2 percent. In this example, the opening area of ​​the diffusion port 161 is about 6 to 15 percent of the opening area of ​​the gasoline supply passage 162. A more desirable range is 10 percent. This is because if the opening area of ​​the diffusion port 161 is narrowed to less than 5 percent, a sufficient amount of oil cannot be supplied to the mixing pump chamber 160. Conversely, if the opening area of ​​the diffusion port 161 is increased by more than 20 percent, the oil content in the mixing pump chamber 160 will be too high.

[0042] The gasoline and oil mixture, mixed in the mixing pump chamber 160, is supplied to the cylinder head 209 of the engine 200 through the mixture outlet passage 165. The mixture outlet passage 165 is formed in the upper housing 110 and the lower housing 150. Of the mixture outlet passages 165, the upper mixture outlet passage 1101, formed in the upper housing 110, has an upper mixture outlet passage locking portion 1101a formed on its outer circumference to prevent the mixture pipe from coming loose. Of the mixture outlet passages 165, the lower mixture outlet passage 1501, formed in the lower housing 150, is L-shaped. The opening of this lower mixture outlet passage 1501 is closed by a lower mixture outlet passage plug 1502. This lower mixture outlet passage plug 1502 is also screwed to the lower housing 150, similar to the oil supply passage plug 159 and the like described above.

[0043] An outlet check valve 181 is positioned in the upper mixed liquid outlet passage 1101. This outlet check valve 181 has the same configuration as the inlet check valve 180. That is, it is a duckbill check valve as shown in Figure 4, made of a flexible material such as nitrile rubber. In this example, the same check valve is used for both the inlet check valve 180 and the outlet check valve 181. However, the outlet check valve 181 only allows the mixed liquid to flow towards the engine through the mixed liquid outlet passage 165, preventing backflow into the mixing pump chamber 160. In this example, the outlet check valve 181 is also sandwiched between the upper housing 110 and the lower housing 150.

[0044] Next, the operation of the mixed liquid pump 100, which has the above configuration, will be explained. When the engine 200 is started and while the engine 200 is running, the piston 202 reciprocates within the cylinder block 203. As a result of this reciprocating motion, the pressure in the crankcase 201 pulsates. In this disclosure, the displacement of the engine 200 is not limited, but even with a small engine 200, pressure fluctuations of about 10 kilopascals occur. These pressure fluctuations are supplied to the pulse chamber 120 via the pressure introduction pipe 1120.

[0045] The mixing pump chamber 160 has openings for a gasoline supply passage 162 and a mixed liquid outlet passage 165, but the internal pressure is approximately atmospheric pressure. Therefore, based on the pressure difference between the mixing pump chamber 160, which is constant at approximately atmospheric pressure, and the pulse chamber 120, which receives pulsations from the crank chamber, the diaphragm 170 reciprocates between the pulse chamber 120 and the mixing pump chamber 160. This reciprocating movement of the diaphragm 170 is supported by an upper diaphragm support spring 112 and a lower diaphragm support spring 152. As described above, the compressive forces of the upper diaphragm support spring 112 and the lower diaphragm support spring 152 are small and balanced. Therefore, even with small pulsations, the diaphragm 170 can reliably reciprocate.

[0046] The pressure inside the mixing pump chamber 160 is approximately atmospheric pressure, but the volume of the mixing pump chamber 160 fluctuates as the diaphragm 170 reciprocates. Specifically, when the diaphragm 170 moves toward the pulse chamber 120, the volume of the mixing pump chamber 160 increases. Conversely, when the diaphragm 170 is displaced toward the mixing pump chamber 160, the volume of the mixing pump chamber 160 decreases. Although the fluctuation in internal pressure is small, the volume fluctuation of the mixing pump chamber 160 allows gasoline to flow in from the gasoline supply passage 162. Since an inlet check valve 180 is located in the gasoline supply passage 162, the gasoline always flows toward the mixing pump chamber 160.

[0047] In a 2-stroke engine 200, the amount of gasoline consumed in one reciprocating motion of the piston 202 is minuscule. On the other hand, pulsation in the crankcase 201 occurs once with each reciprocating motion of the piston 202. That is, the volume of the mixing pump chamber 160 changes once with each reciprocating motion of the piston 202. Even though it is a minuscule amount, the mixing pump chamber 160 reliably receives gasoline from the gasoline supply passage 162.

[0048] Volume fluctuations in the mixing pump chamber 160 are transmitted to the diffusion chamber 164 via the diffusion port 161. The pressure in the diffusion chamber 164 is also approximately atmospheric pressure, similar to that in the mixing pump chamber 160. However, the volume fluctuations in the mixing pump chamber 160 affect the diffusion chamber 164, causing the oil-restricting piston 132 to reciprocate within the oil-restricting passage 131. A small gap is formed between the oil-restricting piston 132 and the oil-restricting passage 131, and oil supplied from the oil supply passage 163 is present in this small gap. As the oil-restricting piston 132 reciprocates, the oil present in the small gap flows into the diffusion chamber 164.

[0049] Here, the amount of oil required is small compared to the amount of gasoline, about 2 percent. Therefore, the amount of oil supplied is limited by the oil limiting mechanism 130. The oil limiting by the oil limiting mechanism 130 is adjusted by rotating the oil supply passage plug 159, which is screwed to the lower housing 150. That is, as it rotates, the position of the oil supply passage plug 159 changes vertically in Figure 1. The lower end of the limiting mechanism support spring 133 is locked to a plug locking portion 135 formed on the oil supply passage plug 159. As a result, the compression force of the limiting mechanism support spring 133 is varied according to the change in the position of the oil supply passage plug 159, and the amount of oil restricted is adjusted according to this change in compression force.

[0050] Within the diffusion chamber 164, there is liquid from the mixing pump chamber 160 flowing in through the diffusion port 161 and oil flowing in through the minute gap. Here, the liquid flowing in from the mixing pump chamber 160 through the diffusion port 161 is mostly gasoline. Therefore, the oil flowing in through the minute gap diffuses into the gasoline within the diffusion chamber 164. In this disclosure, the ratio of oil in the diffusion chamber 164 is adjusted to approximately 10-40% by adjusting the opening area of ​​the diffusion port 161 and the cross-sectional area of ​​the minute gap. As mentioned above, the amount of oil can be adjusted using the oil supply passage plug 159.

[0051] When the diaphragm 170 is displaced downward (towards the mixing pump chamber 160) due to volume fluctuations in the mixing pump chamber 160, liquid flows from the mixing pump chamber 160 into the diffusion chamber 164. Conversely, when the diaphragm 170 is displaced upward (towards the pump chamber 160), liquid in the diffusion chamber 164 flows into the mixing pump chamber 160. As described above, the liquid in the mixing pump chamber 160 is mostly gasoline, while oil makes up about half of the liquid in the diffusion chamber 164. Therefore, the liquid in the mixing pump chamber 160, which is mostly gasoline, contains about 2 percent oil.

[0052] Looking at it in more detail, the oil content of the liquid in the mixing pump chamber 160 is higher than 2 percent near the diffusion port 161, and lower than 2 percent around the opening of the gasoline supply passage 162. Around the opening of the mixed liquid outlet passage 165, the oil content is approximately 2 percent. The mixed liquid pump 100 is configured such that the oil content is approximately 2 percent around the opening of the mixed liquid outlet passage 165, by setting the cross-sectional area of ​​the gasoline supply passage 162, the cross-sectional area of ​​the diffusion port 161, and the volume of the mixing pump chamber 160. As mentioned above, the opening area of ​​the diffusion port 161 is set to less than 20 percent of the cross-sectional area of ​​the gasoline supply passage 162.

[0053] As described above, a gasoline mixture containing approximately 2 percent oil is supplied to the injector 220 from the mixture outlet passage 165. The operation of the mixture pump 100 inevitably increases the pressure of the gasoline mixture. As a result, the pressure of the gasoline mixture in the mixture outlet passage 165 is approximately 100 kilopascals. The gasoline mixture is injected into the engine 200 from the injector 220. Meanwhile, intake air drawn into the crankcase 201 from the intake passage 206 is drawn into the cylinder head 209 of the engine 200 from the scavenging passage 208. The gasoline mixture injected from the injector 220 and the intake air are then mixed in the cylinder head 209. As described above, the amount of gasoline consumed in one piston stroke is minute, so in the normal operating range of the engine 200, there is an excess of gasoline mixture supplied from the mixture pump 100. Therefore, the excess gasoline is returned to a gasoline tank (not shown). For example, if the amount of gasoline injected from the injector into engine 200 is 3 microliters, then the same amount or about twice that amount of excess gasoline will be returned to the fuel tank.

[0054] The above description represents a preferred embodiment of the present disclosure, but the present disclosure is not limited to the above embodiment and can be modified in various ways. For example, the inlet check valve 180 and the outlet check valve 181 may be replaced with other valve bodies. As shown in Figure 5, a ball valve 182 may be used and pressed against the check valve seat 184 by a check valve spring 183. In the example in Figure 5, the compressive force of the check valve spring 183 is set to be small. That is, the compressive force of the check valve spring 183 is set so that the gasoline supply passage 162 and the mixed liquid outlet passage 165 can be opened in accordance with the volume fluctuation of the mixing pump chamber 160.

[0055] The valve may be a spherical piston valve 185, as shown in Figure 6, rather than just the ball valve 182 shown in Figure 5. In the spherical piston valve 185, the contact surface with the check valve seat 184 is hemispherical. In addition, a check valve spring locking portion 186 for locking the check valve spring 183 is formed on the back surface of the spherical piston valve 185.

[0056] Furthermore, a flat piston valve 187, as shown in Figure 7, may also be used. In this case, it is formed on the plane of the check valve seat 184. The formation of the check valve spring locking portion 186 on the back surface is the same as in the embodiment shown in Figure 6. These ball valves 182, spherical piston valves 185, and flat piston valves 187 correspond to the check valve bodies of this disclosure. However, the check valve bodies of this disclosure only need to open and close the check valve seat 184 by receiving the biasing force of the check valve spring 183, and their shape is not limited to the shapes shown in Figures 5 to 7. It is sufficient that the fluid flow can be restricted in one direction.

[0057] Furthermore, in the above-described embodiment, the pulse chamber 120 was connected to the crankcase 201 of the engine 200 via the pressure introduction pipe 1120 to receive the pulsations of the crankcase 201. This is a desirable example as it increases the degree of freedom in the placement of the fuel mixture pump 100. However, as shown in Figures 8 and 9, the fuel mixture pump 100 may also be directly incorporated into the crankcase 201 of the engine 200. A crankcase opening 140 is provided in the upper housing 110, and this crankcase opening 140 opens directly into the crankcase 201 of the engine 200. Assembly to the engine 200 is performed by mounting screw portions 141 formed in the upper housing 110. In the embodiment shown in Figures 8 and 9, it is possible to reduce the overall volume of the engine 200 and the fuel mixture pump 100. In the example shown in Figures 8 and 9, since it is directly incorporated into the engine 200, it is desirable that the upper housing 110 and lower housing 150 be made of metal such as aluminum alloy.

[0058] Figures 10 to 12 show other embodiments of the mixed liquid pump 100 of the present disclosure. In these figures, unlike the examples in Figures 1 and 8, the upper housing 110 constituting the pulse chamber 120 is positioned at the bottom, and the lower housing 150 constituting the mixed pump chamber 160 is positioned at the top. As mentioned above, the designations of upper and lower do not correspond to the vertical direction. The upper housing 110 and the lower housing 150 are connected by retaining bolts 194 together with a retaining plate 193, which will be described later.

[0059] In other embodiments, as shown in Figures 10 and 11, a gasoline supply passage 162 and a mixed liquid outlet passage 165 are arranged in parallel on one surface of the upper lower housing 150. An oil supply passage 163 is integrally formed on the other surface of the lower housing 150. The gasoline supply passage 162 is made of a resin such as polyacetal and is screwed to the lower housing 150. The gasoline supply passage 162 opens directly to the mixing pump chamber 160 via an inlet check valve 180. Similarly, the mixed liquid outlet passage 165 also opens directly to the mixing pump chamber 160 via an outlet check valve 181, as shown in Figure 12. Figure 12 shows an outlet passage threaded portion 165a formed on the outer circumference of the mixed liquid outlet passage 165. The mixed liquid outlet passage 165 is screwed to the lower housing 150 by this outlet passage threaded portion 165a. The mixed liquid outlet passage 165 is also made of a resin such as polyacetal.

[0060] The oil supply passage 163 is connected to the mixing pump chamber 160 via the diffusion chamber 164 and the diffusion port 161. The opening of the oil supply passage 163 is closed by the oil supply passage plug 159, as in the embodiment of Figure 1. A pressure introduction passage 1121 is formed in the upper housing 110 located below Figure 10. As in the embodiment of Figure 1, the pressure from the crank chamber 201 of the engine 200 is introduced into the pulse chamber 120 via the pressure introduction passage 1121.

[0061] The engine 200 of this disclosure can be used for a variety of applications. For example, it can be used as a power source for portable sprayers, blowers, brush cutters, etc., used outdoors. In all of these applications, the engine is typically driven at a constant rotational speed. In the above description, it was stated that the pressure fluctuation range of the crank chamber 201 is 5 kilopascals or more, or about 10 kilopascals. However, specifically, the pressure fluctuation in the crank chamber 201 changes depending on the rotational speed of the engine 200. At high rotational speeds of 10,000 revolutions per minute or more, the pressure in the crank chamber 201 fluctuates by about -20 kilopascals to -30 kilopascals. In this case, the range of fluctuation is about 10 kilopascals.

[0062] On the other hand, at low rotational speeds of around 2,000 revolutions per minute, the pressure fluctuations in the crankcase 201 become larger. Specifically, when the pressure in the crankcase 201 decreases, it ranges from -30 kilopascals to -50 kilopascals. When the pressure in the crankcase 201 increases, it reaches about 10 kilopascals, which is above atmospheric pressure. Therefore, in the low-speed rotation range of the engine 200, the pressure fluctuation range in the crankcase 201 is a maximum of 60 kilopascals, which is considerably larger than the 10 kilopascals at high rotational speeds.

[0063] Other embodiments shown in Figures 10 to 12 are based on the premise that the pressure fluctuation range of the pulse chamber 120 changes according to the rotational speed of the engine 200, and are designed to ensure that the pressure fluctuations of the pulse chamber 120 are reliably transmitted to the mixing pump chamber 160 even when the pressure fluctuation range is small. For this reason, in other embodiments, an auxiliary diaphragm 190 is placed on a surface of the mixing pump chamber 160 other than the surface on which the diaphragm 170 is placed.

[0064] Specifically, the auxiliary diaphragm 190 is positioned to block the atmospheric pressure port 191 connected to the mixing pump chamber 160 of the lower housing 150. The auxiliary diaphragm 190 is held on its outer circumference by a retaining plate 193 having an atmospheric pressure opening 192. The retaining plate 193 is fixed to the lower housing 150 by retaining bolts 194. Therefore, the auxiliary diaphragm 190 receives the pressure of the mixing pump chamber 160 through the atmospheric pressure port 191 on one side, and atmospheric pressure through the atmospheric pressure opening 192 on the other side. Since the atmospheric pressure is constant, the auxiliary diaphragm 190 will be displaced in accordance with the pressure fluctuations in the mixing pump chamber 160.

[0065] As shown in Figure 12, the auxiliary diaphragm 190 is positioned parallel to the diaphragm 170. This is to allow the auxiliary diaphragm 190 to be positioned in the lower housing 150 even if its area is made close to that of the diaphragm 170. This is because the auxiliary diaphragm 190 can function regardless of which surface it is positioned on that forms the mixing pump chamber 160. However, to increase the area of ​​the auxiliary diaphragm 190, it is desirable to position it parallel to the diaphragm 170. By increasing the pressure-receiving area of ​​the auxiliary diaphragm 190, the auxiliary diaphragm 190 is more easily displaced in accordance with the displacement of the diaphragm 170. As mentioned above, the diaphragm 170 has a disc shape with a bent portion 174. In contrast, the auxiliary diaphragm 190 has a flat, circular shape without a bent portion. Therefore, the displacement of the auxiliary diaphragm 190 is smaller than the displacement of the diaphragm 170.

[0066] When the pressure fluctuations in the pulse chamber 120 are large, the displacement of the diaphragm 170 is also large. As a result, the volume fluctuations in the mixing pump chamber 160 are also large, making it easy to open and close the inlet check valve 180 and the outlet check valve 181 to allow gasoline or the fuel mixture to flow. However, when the pressure fluctuations in the pulse chamber 120 are small, the displacement of the diaphragm 170 also becomes small. As a result, the volume fluctuations in the mixing pump chamber 160 also decrease, and the pressure changes within the mixing pump chamber 160 also decrease. Furthermore, as a result of the reduced pressure changes, the function of the mixing pump chamber 160 in drawing in gasoline and discharging the fuel mixture also decreases.

[0067] In other embodiments, the inlet check valve 180 and outlet check valve 181 employ a structure that includes a flat piston valve 187, as shown in Figures 7 and 11. Specifically, it employs a structure that includes a check valve body (flat piston valve 187) that opens and closes the check valve seat 184, and a check valve spring 183 that biases this check valve body toward the check valve seat 184. This is because the check valve body can respond to smaller pressure fluctuations compared to the duckbill valve shown in Figures 1 and 4.

[0068] In other embodiments, an auxiliary diaphragm 190 is provided to facilitate the pumping action of the mixing pump chamber 160. As described above, the auxiliary diaphragm 190 displaces in accordance with the displacement of the diaphragm 170. Therefore, volume fluctuations in the mixing pump chamber 160 can be achieved through the cooperation of the diaphragm 170 and the auxiliary diaphragm 190. In other words, even if the diaphragm 170 alone is insufficient to generate a flow of gasoline or a mixed liquid within the mixing pump chamber 160, fluid flow becomes easier to generate within the mixing pump chamber 160. This is because the diaphragm 170 and the auxiliary diaphragm 190 displace in cooperation, suppressing stagnation of the fluid flow in the mixing pump chamber 160.

[0069] To put it another way, in the description of the embodiment shown in Figure 1 above, it was assumed that the pressure inside the mixing pump chamber 160 was approximately atmospheric pressure. However, strictly speaking, the pressure inside the mixing pump chamber 160 in the embodiment shown in Figure 1 is not constant atmospheric pressure. This is because the flow resistance of gasoline and the mixed liquid, as well as the flow resistance of the inlet check valve 180 and the outlet check valve 181, are added to the mixing pump chamber 160. In contrast, in other embodiments, an atmospheric pressure hole 191 is opened in the lower housing 150, so the pressure inside the mixing pump chamber 160 can be maintained at atmospheric pressure. It can also be said that the auxiliary diaphragm 190 fluctuates in order to maintain the pressure inside the mixing pump chamber 160 at atmospheric pressure. Because the pressure inside the mixing pump chamber 160 can be maintained at atmospheric pressure by the auxiliary diaphragm 190, gasoline and oil can flow more easily in accordance with the displacement of the diaphragm 170.

[0070] In any case, the diaphragm 170 is the main component that generates fluid flow within the mixing pump chamber 160. The auxiliary diaphragm 190 merely assists the behavior of the diaphragm 170. Therefore, as mentioned above, the displacement of the auxiliary diaphragm 190 is smaller than that of the diaphragm 170. Even a small displacement of the auxiliary diaphragm 190 helps maintain the pressure inside the mixing pump chamber 160 at atmospheric pressure, thereby suppressing stagnation of the fluid flow.

[0071] In addition to the embodiment shown in Figure 12, the oil limiting mechanism 130 is also provided with a limiting mechanism support spring 133 in the embodiments shown in Figures 1 and 8 described above. This is desirable because it stabilizes the behavior of the oil limiting piston 132. However, it is possible to eliminate the limiting mechanism support spring 133 if necessary.

[0072] The same applies to the upper diaphragm support spring 112 and the lower diaphragm support spring 152. To stabilize the behavior of the diaphragm 170, it is desirable to use the upper diaphragm support spring 112 and the lower diaphragm support spring 152. For reasons such as cost reduction and improved assembly, it is also possible to eliminate the upper diaphragm support spring 112 and the lower diaphragm support spring 152.

[0073] In the example described above, the gasoline mixture discharged from the mixture pump 100 was injected into the engine 200 via the injector 220. However, the injector is not a mandatory component. The gasoline mixture from the mixture pump 100 could also be supplied to the intake passage 206 of the engine 200.

[0074] In the above example, an oil-restricting piston 132 or the like is used as the oil-restricting mechanism 130. This is a desirable embodiment for restricting the supply of oil to the diffusion chamber 164. However, the oil-restricting mechanism 130 only needs to be able to restrict the amount of oil supplied, and it is also possible to restrict the supply amount by placing an orifice in the oil supply passage 163, for example.

[0075] Furthermore, the materials described above are just examples of the present disclosure. For example, the upper housing 110 and lower housing 150 in the embodiments shown in Figures 1 and 2 can be made of metal, as in the embodiments shown in Figures 8 and 9. Also, the sizes described above are just examples, and it is possible to make the mixed fluid pump 100 larger or smaller to suit the required engine specifications.

[0076] Furthermore, a preferred use of the mixed liquid pump 100 is to supply a mixture of gasoline and oil to a two-stroke engine. However, as a pump that supplies two types of liquids while mixing them, the mixed liquid pump 100 of this disclosure is not limited to two-stroke engines. [Explanation of symbols]

[0077] 100 Mixing Liquid Pump 120 pulse chamber 130 Oil limiting mechanism 160 Mixing pump room 161 Diffusion port 162 Gasoline supply channel 163 Oil supply passage 164 Diffusion Chamber 165 Mixed liquid outlet passage 170 diaphragm 180 Inlet check valve 181 Outlet check valve 190 Auxiliary diaphragm

Claims

1. A pulse chamber (120) in which the internal pressure fluctuates in response to external pulsations, This pulse chamber is closed, and a diaphragm (170) that displaces in accordance with the pressure fluctuations in the pulse chamber, A mixing pump chamber (160) is positioned opposite the pulse chamber with the diaphragm in between, and its internal volume changes according to the displacement of the diaphragm. This mixing pump chamber has a first liquid inlet passage (162) through which the first liquid flows, An inlet check valve (180) is provided in this first inlet passage, which allows only the flow of the first liquid into the mixing pump chamber and prevents backflow from the mixing pump chamber, A second liquid supply passage (163) for supplying the second liquid to the mixing pump chamber, A diffusion port (161) is formed at the end of this second liquid supply passage on the mixing pump chamber side, and its opening area is smaller than the opening area of ​​the first liquid inlet passage. A diffusion chamber (164) is formed on the second liquid supply passage side of this diffusion port, which diffuses the second liquid into the first liquid, A second liquid limiting mechanism (130) is located on the second liquid supply passage side of the diffusion chamber and limits the amount of the second liquid flowing from the second liquid supply passage to the diffusion chamber, A mixed liquid outlet passage (165) from which a mixture of the first liquid and the second liquid flows out of the aforementioned mixing pump chamber, An outlet check valve (181) is provided in the mixed liquid outlet passage, which allows only the flow of the mixed liquid out of the mixing pump chamber and prevents backflow into the mixing pump chamber. Equipped with, The mixed liquid pump (100) is characterized in that the second liquid limiting mechanism has a second liquid limiting passage (131) formed between the diffusion chamber and the second liquid supply passage, and is a mechanism that limits the flow area of ​​the second liquid limiting passage to limit the flow rate of the second liquid passing through the second liquid limiting passage.

2. The second liquid limiting mechanism comprises a second liquid limiting piston (132) disposed within the second liquid limiting passage with a small gap between them and capable of reciprocating within the second liquid limiting passage. The pressure in the diffusion chamber fluctuates in accordance with the volume fluctuations of the mixing pump chamber, and the second liquid limiting piston reciprocates in response to the pressure fluctuations in the diffusion chamber. The second liquid from the second liquid supply passage is supplied to the diffusion chamber through a minute gap between the second liquid limiting piston and the second liquid limiting passage in accordance with the reciprocating movement of the second liquid limiting piston. The mixed liquid pump according to feature 1.

3. The second liquid limiting mechanism includes a limiting mechanism support spring (133) that supports the reciprocating movement of the second liquid limiting piston. The mixed liquid pump according to feature 2.

4. The opening area of ​​the diffusion port is less than 20 percent of the opening area of ​​the first liquid inlet passage. The mixed liquid pump according to feature 1.

5. The first liquid is gasoline, and the second liquid is oil. The pulse chamber communicates with the engine's crankcase and receives pressure pulsations within the crankcase. A mixture of gasoline and oil is supplied to the engine from the aforementioned mixture outlet passage. The mixed liquid pump according to feature 1.

6. The pulse chamber and the mixing pump chamber are provided with diaphragm support springs (112, 152) that support the diaphragm. The mixed liquid pump according to feature 1.

7. Of the surfaces forming the mixing pump chamber, an auxiliary diaphragm (190) is arranged on a surface other than the surface on which the diaphragm is arranged. This auxiliary diaphragm receives the pressure of the mixing pump chamber on one side and atmospheric pressure on the other side, and the auxiliary diaphragm is displaced in accordance with the pressure fluctuations in the mixing pump chamber. The mixed liquid pump according to feature 1.

8. The auxiliary diaphragm is positioned parallel to the diaphragm and displaces in accordance with the displacement of the diaphragm. The mixed liquid pump according to feature 7.

9. The diaphragm has a disc shape with a bent portion, and the auxiliary diaphragm has a flat, circular shape without a bent portion. The displacement of the auxiliary diaphragm is smaller than the displacement of the aforementioned diaphragm. The mixed liquid pump according to feature 7.

10. The inlet and outlet check valves each include a check valve seat (184), check valve bodies (182, 185, 187) that open and close the check valve seat, and a check valve spring (183) that biases the check valve bodies toward the check valve seat. The mixed liquid pump according to feature 1.

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