Liquid mixture 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

[0001] The present disclosure relates to a mixed liquid pump that inhales and mixes two types 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-stroke engine.

Background Art

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

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The pump of Patent Document 1 integrates a fuel pump and an oil pump. Gasoline is supplied from the fuel pump to the engine through the fuel outlet passage, and oil is supplied from the oil pump to the engine through the oil feed line.

[0005] The present disclosure aims not only to simply integrate pumps for two types of liquids, but also to enable the two types of liquids to be mixed in an appropriate ratio. Furthermore, an object of the present disclosure is to provide a mixed liquid pump capable of discharging the liquid mixed in an appropriate ratio. For example, when a fuel pump and an oil pump are integrated, gasoline and oil can be mixed in a predetermined ratio inside the mixed liquid pump, and the mixed liquid can be supplied to a two-stroke engine.

Means for Solving the Problems

[0006] One aspect of the present disclosure includes a pulse chamber (120) whose internal pressure fluctuates in response to an external pulsation, a diaphragm (170) that closes the pulse chamber and displaces in response to the pressure fluctuation of the pulse chamber, and a mixing pump chamber (160) that is disposed opposite the pulse chamber with the diaphragm interposed therebetween and whose internal volume fluctuates in response to the displacement of the diaphragm. One aspect of the present disclosure is a mixed liquid pump that converts an external pulsation into a volume fluctuation of the mixing pump chamber using a diaphragm.

[0007] One aspect of the present disclosure includes a first liquid inlet passage (162) through which a first liquid flows into the mixing pump chamber, an inlet check valve (180) disposed in the first inlet passage that 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) that supplies a second liquid to the mixing pump chamber. One aspect of the present disclosure is a mixed liquid pump in which a first liquid and a second liquid are supplied to a single mixing pump chamber.

[0008] One aspect of the present disclosure includes a diffusion port (161) formed at an end of the second liquid supply passage on the mixing pump chamber side, the opening area of which is narrower 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 that diffuses the second liquid into the first liquid, and a second liquid restricting mechanism (130) disposed on the second liquid supply passage side of the diffusion chamber that restricts the amount of the second liquid flowing from the second liquid supply passage into the diffusion chamber. One aspect of the present disclosure disposes a diffusion port, a diffusion chamber, and a second liquid restricting mechanism between the mixing pump chamber and the second liquid inlet passage. An amount of the second liquid restricted by the second liquid restricting mechanism flows into the diffusion chamber, and the second liquid diffuses into the first liquid in the diffusion chamber. Then, the mixed liquid in which the second liquid has diffused flows into the mixing pump chamber through the diffusion port.

[0009] One aspect of the present disclosure includes a mixed liquid outlet passage (165) through which a mixed liquid of the first liquid and the second liquid flows out of the mixing pump chamber, and an outlet check valve (181) disposed in the 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 aspect of the present disclosure, the mixed liquid of the first liquid and the second liquid mixed in the mixing pump chamber is allowed to flow out.

[0010] In other aspects of the present disclosure, the second liquid restricting mechanism includes a second liquid restricting passage (131) formed between the diffusion chamber and the second liquid supply passage, and a second liquid restricting piston (132) disposed in the second liquid restricting passage via a minute gap and reciprocally movable within the second liquid restricting passage. The pressure in the diffusion chamber varies according to the volume fluctuation of the mixing pump chamber, and the second liquid restricting piston reciprocates in response to the pressure fluctuation in the diffusion chamber. The oil from the second liquid supply passage is supplied to the diffusion chamber through the minute gap between the second liquid restricting piston and the second liquid restricting passage according to the reciprocating movement of the second liquid restricting piston. In other aspects of the present disclosure, the supply of the second liquid can be restricted by utilizing the minute gap between the second liquid restricting piston and the second liquid restricting passage.

[0011] Still other second liquid restricting mechanisms of the present disclosure include a restricting mechanism support spring (133) that supports the reciprocating movement of the second liquid restricting piston. By the restricting mechanism support spring, the reciprocating movement of the second liquid restricting piston can be smoothed.

[0012] In still other aspects of the present disclosure, the opening area of the diffusion port is made smaller than 20 percent of the opening area of the first liquid inlet passage. What flows into the mixing pump chamber from the diffusion port is a mixed liquid in which the second liquid has diffused into the first liquid in the diffusion chamber. By making the opening area of the diffusion port smaller than 20 percent of the opening area of the first liquid inlet passage, the amount of the mixed liquid flowing in from the diffusion port can be suppressed. Thereby, the amount of the second liquid flowing into the mixing pump chamber can be made about 2 percent of the whole.

[0013] In still other aspects of the present disclosure, the first liquid is gasoline and the second liquid is oil. The pulse chamber communicates with the crank chamber of the engine and receives the pressure pulsation in the crank chamber. Also, a mixed liquid of gasoline and oil is supplied from the mixed liquid outlet passage to the engine. Still other mixing liquid pumps of the present disclosure are used to supply a mixed liquid of gasoline and oil to a two-stroke engine.

[0014] In still other aspects of the present disclosure, diaphragm support springs (112, 152) that support the diaphragm are disposed in the pulse chamber and the mixing pump chamber. By disposing the diaphragm support springs, the reciprocating movement behavior of the diaphragm can be stabilized.

[0015] In still other aspects of the present disclosure, an auxiliary diaphragm (190) is disposed on a surface of the surface forming the mixing pump chamber other than the surface on which the diaphragm is disposed. And, one surface of the auxiliary diaphragm receives the pressure of the mixing pump chamber and the other surface receives the atmospheric pressure. Also, the auxiliary diaphragm is displaced in response to pressure fluctuations in the mixing pump chamber. By disposing the auxiliary diaphragm, the pressure in the mixing pump chamber is maintained at atmospheric pressure, making it easier for the volume of the mixing pump chamber to fluctuate.

[0016] In still other aspects of the present disclosure, the auxiliary diaphragm is disposed parallel to the diaphragm. Therefore, it is easier to dispose the auxiliary diaphragm. Also, the auxiliary diaphragm is displaced in response to the displacement of the diaphragm. That is, the auxiliary diaphragm is more easily displaced in response to the displacement of the diaphragm. The action of making it easier for the volume of the mixing pump chamber to fluctuate can be performed more efficiently.

[0017] In still other aspects of the present disclosure, the diaphragm has a disk shape with a bent portion (174), and the auxiliary diaphragm has a flat circular shape without a bent portion. Therefore, the displacement amount of the auxiliary diaphragm is smaller than that of the diaphragm. The auxiliary diaphragm merely assists the diaphragm to make the pressure in the mixing pump chamber atmospheric pressure and complements the volume fluctuation. Therefore, the displacement amount of the auxiliary diaphragm is smaller than that of the diaphragm.

[0018] In yet another aspect 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) for opening and closing the check valve seat, and a check valve spring (183) for biasing the check valve body toward the check valve seat side. Even in a state where 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

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Modes for Carrying Out the Invention

[0020] The mixing liquid pump 100 of the present disclosure will be described with reference to FIG. 1. The mixing liquid pump 100 includes an upper housing 110 and a lower housing 150. Note that the upper housing 110 and the lower housing 150 are arranged as shown in FIG. 1, and do not indicate the vertical direction in the actual use state. The same applies to the following upper and lower notations, which do not indicate the vertical direction in the use state. Both the upper housing 110 and the lower housing 150 are formed by injection molding a resin excellent in gasoline resistance. As the resin material, for example, polyacetal resin is used.

[0021] A diaphragm 170 is disposed between the upper housing 110 and the lower housing 150. The diaphragm 170 is made of a flexible material, for example, nitrile rubber or fluororubber. The outer periphery 171 of the diaphragm 170 is clamped between the upper housing 110 and the lower housing 150. Also, the central portion 172 of the diaphragm 170 is clamped between the upper plate 111 and the lower plate 151. The upper plate 111 and the lower plate 151 are also made of resin and are injection molded with, for example, polyacetal resin. Between the outer periphery 171 and the central portion 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 easy to displace in the vertical direction of FIG. 1.

[0022] A pulse chamber 120 is formed between the diaphragm 170 and the upper housing 110. The pulse chamber 120 communicates with the crank chamber 201 of the engine 200 shown in FIG. 2 via a pressure introduction passage 1121 and a pressure introduction pipe 1120. Note that a pressure introduction passage locking portion 1121a for preventing the pressure introduction pipe 1120 connected to the crank chamber 201 from coming off is formed on the outer periphery of the pressure introduction passage 1121.

[0023] Here, the structure of the two-cycle engine 200 will be briefly described. In FIG. 2, the piston 202 reciprocates within the cylinder block 203, and the reciprocating movement of the piston 202 is transmitted to the crankshaft 205 via the connecting rod 204. At this time, the reciprocating movement of the piston 202 is converted into the rotational movement of the crankshaft 205, and the crankshaft 205 rotates within the crank chamber 201. 2050 is a web, and when the crankshaft 205 rotates, the web 2050 balances the rotation with the piston 202.

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

[0025] FIG. 2 shows the exhaust process and the scavenging process of the two-cycle engine 200 when the piston 202 moves downward in the figure. The intake air inhaled into the crank chamber 201 is supplied to the cylinder head 209 from the scavenging passage 208 in the scavenging process. The intake air supplied to the cylinder head 209 is compressed in the compression process when the piston 202 rises together with the mixture of gasoline and oil injected from the injector 220. The compressed intake air and gasoline burn due to the ignition of the spark plug 210, and the volume expands. Due to this volume expansion, the piston 202 is pushed down to the state shown in FIG. 2. In this state, the exhaust gas is exhausted from the exhaust port 211 to the exhaust passage 212. An exhaust valve 213 for preventing the backflow of exhaust is disposed in the exhaust passage 212.

[0026] In the two - cycle engine 200, a compression process, an expansion process, and an exhaust scavenging process are repeated, and the piston 202 reciprocates within the cylinder block 203. In response to the reciprocating movement of this piston 202, the pressure in the crank chamber 201 pulsates. Therefore, the pressure in the pulse chamber 120, which has the same pressure as the crank chamber 201, also pulsates. The pulsation of the crank chamber 201 varies depending on the size of the engine 200, but in the case of an engine 200 with a volume of about 30 to 90 cc (cubic centimeters), the pressure fluctuation is at least about 5 kilopascals. Note that the pressure fluctuation of the engine 200 will be described later.

[0027] On the opposite side of the pulse chamber 120 across the diaphragm 170, a mixing pump chamber 160 is formed. That is, the mixing pump chamber 160 is formed in the lower housing 150, and the upper surface of the surfaces forming the mixing pump chamber 160 is closed by the diaphragm 170. The pressure inside the pulse chamber 120 fluctuates in response to the pulsation of the crank chamber 201. On the other hand, the pressure in the mixing pump chamber 160 is approximately atmospheric pressure and does not have large fluctuations. Therefore, the diaphragm 170 reciprocates between the pulse chamber 120 and the mixing pump chamber 160 in response to the pressure fluctuation of the pulse chamber 120. As described above, the diaphragm 170 is provided with a bent portion 174, which facilitates reciprocating movement. Note that 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 the present disclosure, the diaphragm support spring refers to the upper diaphragm support spring 112 and the lower diaphragm support spring 152 collectively.

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

[0029] Note that the lower end of the upper diaphragm support spring 112 is held by the upper shoulder 113 formed on the upper plate 111. Also, the upper end of the upper diaphragm support spring 112 abuts against the upper receiving portion 114 formed on the upper housing 110. And, as a whole, the outer periphery of the upper diaphragm support spring 112 is held by the holding hole 115 formed in the upper housing 110, and the inner periphery is held by the upper holding convex portion 116 formed in the upper housing 110.

[0030] The same applies to the lower diaphragm support spring 152. The upper end of the lower diaphragm support spring 152 is held by the lower shoulder 153 formed on the lower plate 151. Also, the lower end of the lower diaphragm support spring 152 abuts against the lower receiving portion 154 formed in the lower housing 150. And, as a whole, the lower diaphragm support spring 152 is disposed in the mixing pump chamber 160 formed in the lower housing 150, and the inner periphery is held by the lower holding convex portion 155 formed in the lower housing 150. Note that a communication passage 156 connecting the diffusion port 161, which will be described later, and the mixing pump chamber 160 is formed in the lower holding convex portion 155.

[0031] As described above, since the pressure fluctuation in the pulse chamber 120 is not large, the compression force of both the upper diaphragm support spring 112 and the lower diaphragm support spring 152 is set small. For example, the set pressure is 0.5 Newton or less. And, the upper diaphragm support spring 112 and the lower diaphragm support spring 152 have the same compression 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] In the upper housing 110 and the lower housing 150, a gasoline supply passage 162 for supplying gasoline, which is the first liquid, to the mixing pump chamber 160 is formed. The first liquid supply passage in the present disclosure corresponds to the gasoline supply passage 162. Inside the gasoline supply passage 162, an upper gasoline supply passage portion 117 formed in the upper housing 110 is formed with an upper gasoline supply passage locking portion 117a that prevents the fuel pipe from coming off on the outer periphery. Inside the gasoline supply passage 162, a lower gasoline supply passage 157 formed in the lower housing 150 is formed in an L shape. The opening of this lower gasoline supply passage 157 is closed by a lower gasoline supply passage plug 158. Note that the lower gasoline supply passage plug 158 is screwed to the lower housing 150.

[0033] An inlet check valve 180 is disposed in the lower gasoline supply passage 157. As shown in FIG. 4, the inlet check valve 180 is a duckbill check valve and is made of a flexible material such as nitrile rubber. The inlet check valve 180 allows only the flow of gasoline from the gasoline supply passage 162 toward the mixing pump chamber 160 and prevents the 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 for supplying oil, which is the second liquid, to the mixing pump chamber 160 is formed in the lower housing 150. The second liquid supply passage in the present disclosure corresponds to this oil supply passage 163. The oil supply passage 163 is also formed with an oil supply passage locking portion 163a that prevents the oil pipe from coming off on the outer periphery. 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 in the same manner as the lower gasoline supply passage plug 158.

[0035] In the lower housing 150, a diffusion chamber 164 is formed between the diffusion port 161 and the oil supply passage 163. As shown in FIG. 3, the diffusion port 161 is a pore having a diameter of about 0.2 millimeters. Further, the diffusion chamber 164 is a small chamber having a volume of about 2 cubic millimeters. In the lower housing 150, an oil restriction mechanism 130 is further disposed between the diffusion chamber 164 and the oil supply passage 163. This oil restriction mechanism 130 corresponds to the second liquid restriction mechanism of the present 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 disposed in the oil restriction passage 131 via a minute gap. The minute gap only needs to allow the oil restriction piston 132 to move smoothly in the oil restriction passage 131, and is, for example, about 0.05 millimeters. These oil restriction passage 131 and oil restriction piston 132 correspond to the second fluid restriction passage and the second fluid restriction piston in the present disclosure.

[0037] The oil restriction mechanism 130 further includes a restriction mechanism support spring 133 that presses the oil restriction piston 132 toward the diffusion chamber 164 side. The upper end of the restriction mechanism support spring 133 is engaged with a piston locking portion 134 formed on the oil restriction piston 132. The lower end of the restriction mechanism support spring 133 is engaged with a plug locking portion 135 formed on the oil supply passage plug 159. Thereby, the restriction mechanism support spring 133 supports the reciprocating movement of the oil restriction piston 132.

[0038] In response to the volume change of the mixing pump chamber 160, the oil restriction piston 132 reciprocates in the oil restriction passage 131. Due to the reciprocating movement of the oil restriction piston 132, the oil intervening between the oil restriction piston 132 and the oil restriction passage 131 flows into the diffusion chamber 164. That is, an amount of oil restricted by the oil restriction mechanism 130 flows into the diffusion chamber 164.

[0039] Also, in response to the volume change of the mixing pump chamber 160, gasoline that has flowed into the mixing pump chamber 160 also flows into the diffusion chamber 164 through the diffusion port 161. Therefore, the amount of oil restricted by the oil restriction mechanism 130 will diffuse into the gasoline within the diffusion chamber 164. For example, within the diffusion chamber 164, the mixing ratio of gasoline and oil is approximately 10% to 40%. The mixing ratio of oil in the diffusion chamber 164 is higher than that in the mixing pump chamber 160. However, the mixing ratio of oil 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 change of the mixing pump chamber 160 accompanying the reciprocating movement of the diaphragm 170. Therefore, the above-mentioned 10% to 40% is an example of the mixing ratio of oil.

[0040] The volume change of the mixing pump chamber 160 not only causes the liquid to flow from the mixing pump chamber 160 to the diffusion chamber 164, but also causes the liquid to flow from the diffusion chamber 164 to the mixing pump chamber 160. Therefore, the mixed liquid of gasoline and oil mixed in the diffusion chamber 164 flows into the mixing pump chamber 160 from the diffusion port 161. The oil component of the flowing-in mixed liquid further diffuses within the mixing pump chamber 160.

[0041] As a result, the liquid within the mixing pump chamber 160 is mostly gasoline, and becomes a mixed liquid with an oil ratio of approximately 2%. In other words, the opening area of the diffusion port 161 and the opening area of the gasoline supply passage 162 are determined such that the oil ratio in the mixed liquid is approximately 2%. In this example, the opening area of the diffusion port 161 is approximately 6% to 15% of the opening area of the gasoline supply passage 162. A more desirable degree is 10%. This is because if the opening area of the diffusion port 161 is narrowed to less than 5%, 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 enlarged to 20% or more, the oil content in the mixing pump chamber 160 will become too high.

[0042] The gasoline and oil mixture mixed in the mixing pump chamber 160 is supplied from the mixture outlet passage 165 to the cylinder head 209 of the engine 200. The mixture outlet passage 165 is formed in the upper housing 110 and the lower housing 150. Inside the mixture outlet passage 165, in the upper mixture outlet passage 1101 formed in the upper housing 110, an upper mixture outlet passage locking portion 1101a that prevents the mixture pipe from coming off is formed on the outer periphery. Inside the mixture outlet passage 165, the lower mixture outlet passage 1501 formed in the lower housing 150 is formed in an L shape. 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 in the same manner as the above-described oil supply passage plug 159 and the like.

[0043] An outlet check valve 181 is arranged in the upper mixture 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 shown in FIG. 4 and is made of a flexible material such as nitrile rubber. In this example, the same check valve is used for the inlet check valve 180 and the outlet check valve 181. However, the outlet check valve 181 allows only the flow of the mixture from the mixture outlet passage 165 toward the engine and prevents backflow into the mixing pump chamber 160. In this example, the outlet check valve 181 is also clamped by the upper housing 110 and the lower housing 150.

[0044] Next, the operation of the mixture pump 100 having the above configuration will be described. When the engine 200 is started and during the operation of the engine 200, the piston 202 reciprocates in the cylinder block 203. Along with this reciprocating motion, the pressure in the crank chamber 201 pulsates. In the present disclosure, although the displacement of the engine 200 is not limited, even in a small engine 200, a pressure fluctuation of about 10 kilopascals occurs. This pressure fluctuation is supplied to the pulse chamber 120 via the pressure introduction pipe 1120.

[0045] The gasoline supply passage 162 and the mixture outlet passage 165 open into the mixing pump chamber 160, and the internal pressure is substantially atmospheric pressure. Therefore, based on the differential pressure between the mixing pump chamber 160 at a substantially constant atmospheric pressure and the pulse chamber 120 that receives the pulsation of the crank chamber, the diaphragm 170 reciprocates between the pulse chamber 120 and the mixing pump chamber 160. The reciprocating movement of this diaphragm 170 is supported by the upper diaphragm support spring 112 and the 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 a small pulsation, the diaphragm 170 can surely reciprocate.

[0046] Although the pressure in the mixing pump chamber 160 is substantially atmospheric pressure, the volume of the mixing pump chamber 160 varies with the reciprocating movement of the diaphragm 170. That is, when the diaphragm 170 moves toward the pulse chamber 120 side, the volume of the mixing pump chamber 160 increases. Conversely, when the diaphragm 170 is displaced toward the mixing pump chamber 160 side, the volume of the mixing pump chamber 160 decreases. Although the fluctuation of the internal pressure is small, the mixing pump chamber 160 can allow gasoline to flow in from the gasoline supply passage 162 due to the volume fluctuation. Since the inlet check valve 180 is arranged in the gasoline supply passage 162, the gasoline always flows toward the mixing pump chamber 160.

[0047] In the two-cycle engine 200, the amount of gasoline consumed in one reciprocation of the piston 202 is very small. On the other hand, the pulsation of the crank chamber 201 occurs once in one reciprocation of the piston 202. That is, the volume of the mixing pump chamber 160 fluctuates once in one reciprocation of the piston 202. Even with a very small amount, the mixing pump chamber 160 surely receives the supply of gasoline from the gasoline supply passage 162.

[0048] The volume fluctuation of the mixing pump chamber 160 is also transmitted to the diffusion chamber 164 through 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 influence of the volume fluctuation of the mixing pump chamber 160 also reaches into the diffusion chamber 164, causing the oil restriction piston 132 to reciprocate within the oil restriction passage 131. A minute gap is formed between the oil restriction piston 132 and the oil restriction passage 131, and oil supplied from the oil supply passage 163 exists in this minute gap. As the oil restriction piston 132 reciprocates, the oil present in the minute gap flows into the diffusion chamber 164.

[0049] Here, the required amount of oil is small compared to the amount of gasoline, about 2 percent. Therefore, the oil supply amount is restricted by the oil restriction mechanism 130. And the restriction of oil by the oil restriction mechanism 130 is adjusted by rotating the oil supply passage plug 159 screwed to the lower housing 150. That is, as it rotates, the position of the oil supply passage plug 159 changes vertically in FIG. 1. Also, the lower end of the restriction mechanism support spring 133 is locked to the plug locking portion 135 formed on the oil supply passage plug 159. Therefore, the compression force of the restriction mechanism support spring 133 is variable according to the position change of the oil supply passage plug 159, and the throttle amount of oil is adjusted according to the change in this compression force.

[0050] In the diffusion chamber 164, there will be liquid from the mixing pump chamber 160 flowing in through the diffusion port 161 and oil flowing in from the minute gap. Here, most of the liquid flowing in from the mixing pump chamber 160 through the diffusion port 161 is gasoline. Therefore, the oil flowing in from the minute gap will diffuse into the gasoline in the diffusion chamber 164. In the present disclosure, by adjusting the opening area of the diffusion port 161 and the cross-sectional area of the minute gap, the ratio of oil in the diffusion chamber 164 is made to be approximately 1 to 4 percent. Also, as described above, the adjustment of the oil amount at this time is possible by the oil supply passage plug 159.

[0051] Due to the volume change of the mixing pump chamber 160, when the diaphragm 170 is displaced downward (toward 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 (toward the pump chamber 160), the 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, and in the diffusion chamber 164, oil occupies about half. Therefore, the liquid, which is mostly gasoline in the mixing pump chamber 160, contains about 2 percent oil.

[0052] Looking more specifically, in the liquid in the mixing pump chamber 160, near the diffusion port 161, the ratio of oil is higher than 2 percent, and the ratio of oil around the opening of the gasoline supply passage 162 is lower than 2 percent. Around the opening of the mixed liquid outlet passage 165, the ratio of oil is about 2 percent. For the mixed liquid pump 100, 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 are set so that the ratio of oil is about 2 percent around the opening of the mixed liquid outlet passage 165. As described above, the opening area of the diffusion port 161 is less than 20 percent of the cross-sectional area of the gasoline supply passage 162.

[0053] A gasoline mixture containing about 2% oil is supplied from the mixture outlet passage 165 to the injector 220 as described above. Due to the operation of the mixture pump 100, the gasoline mixture is inevitably pressurized. Therefore, in the mixture outlet passage 165, the gasoline mixture has a pressure of about 100 kilopascals. The gasoline mixture is injected from the injector 220 into the engine 200. On the other hand, the intake air inhaled from the intake passage 206 into the crank chamber 201 is inhaled from the scavenging passage 208 into the cylinder head 209 of the engine 200. Then, the gasoline mixture injected from the injector 220 and the intake air are mixed in the cylinder head 209. As described above, since the amount of gasoline consumed in one reciprocation of the piston is very small, in the normal use range of the engine 200, the gasoline mixture supplied from the mixture pump 100 is surplus. Therefore, the surplus gasoline is returned to a gasoline tank (not shown). For example, if the amount of gasoline injected from the injector into the engine 200 is 3 microliters, the same amount or about twice the amount of surplus gasoline is returned to the gasoline tank.

[0054] Note that the above description is a preferred embodiment of the present disclosure, but the present disclosure is not limited to the above embodiment and can be variously modified. For example, the inlet check valve 180 and the outlet check valve 181 may be other valve bodies. As shown in FIG. 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 of FIG. 5, the compression force of the check valve spring 183 is set small. That is, the compression force of the check valve spring 183 is set so that the gasoline supply passage 162 and the mixture outlet passage 165 can be opened according to the volume fluctuation of the mixing pump chamber 160.

[0055] Not limited to the ball valve 182 shown in FIG. 5, a spherical piston valve 185 shown in FIG. 6 may be used. In the spherical piston valve 185, the contact surface with the check valve seat 184 is hemispherical. Further, on the back surface of the spherical piston valve 185, a check valve spring locking portion 186 for locking the check valve spring 183 is formed.

[0056] Furthermore, as shown in FIG. 7, a flat piston valve 187 may also be used. In this case, it is formed on the flat surface of the check valve seat 184. Forming a check valve spring locking portion 186 on the back surface is the same as in the embodiment of FIG. 6. These ball valves 182, spherical piston valves 185, and flat piston valves 187 correspond to the check valve body of the present disclosure. However, the check valve body of the present disclosure only needs to open and close the check valve seat 184 under the urging force of the check valve spring 183, and its shape is not limited to the shapes shown in FIGS. 5 to 7. As long as the fluid flow can be regulated in one direction.

[0057] Also, in the above-described embodiment, the pulse chamber 120 communicates with the crank chamber 201 of the engine 200 via the pressure introduction pipe 1120 to receive the pulsation of the crank chamber 201. This is a desirable example as it increases the degree of freedom in the arrangement position of the mixture pump 100. However, as shown in FIGS. 8 and 9, the mixture pump 100 may be directly incorporated into the crank chamber 201 of the engine 200. An opening 140 to the crank chamber is provided in the upper housing 110, and this opening 140 to the crank chamber directly opens into the crank chamber 201 of the engine 200. The assembly with the engine 200 is performed by the mounting screw portion 141 formed on the upper housing 110. In the embodiments shown in FIGS. 8 and 9, it is possible to reduce the overall volume of the engine 200 and the mixture pump 100. In the examples shown in FIGS. 8 and 9, since it is directly assembled to the engine 200, it is desirable that the materials of the upper housing 110 and the lower housing 150 be made of metal such as an aluminum alloy.

[0058] FIGS. 10 to 12 show other embodiments of the mixture pump 100 of the present disclosure. In these figures, unlike the examples of FIGS. 1 and 8, the upper housing 110 constituting the pulse chamber 120 is disposed downward, and the lower housing 150 constituting the mixing pump chamber 160 is disposed upward. As described above, the upper and lower designations do not correspond to the top and bottom directions. The upper housing 110 and the lower housing 150 are connected by holding bolts 194 together with a holding plate 193 described later.

[0059] In other embodiments, as shown in FIGS. 10 and 11, a gasoline supply passage 162 and a mixture outlet passage 165 are arranged in parallel on one surface of the lower housing 150 located above. Also, 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. And the gasoline supply passage 162 directly opens into the mixing pump chamber 160 through an inlet check valve 180. Similarly, as shown in FIG. 12, the mixture outlet passage 165 also directly opens into the mixing pump chamber 160 through an outlet check valve 181. FIG. 12 shows an outlet passage thread portion 165a formed on the outer periphery of the mixture outlet passage 165. The mixture outlet passage 165 is screwed to the lower housing 150 by this outlet passage thread portion 165a. The mixture outlet passage 165 is also made of a resin such as polyacetal.

[0060] And the oil supply passage 163 communicates with the mixing pump chamber 160 through a diffusion chamber 164 and a diffusion port 161. That the opening of the oil supply passage 163 is closed by an oil supply passage plug 159 is the same as in the embodiment of FIG. 1. A pressure introduction passage 1121 is formed in the upper housing 110 located below FIG. 10. Similar to the embodiment of FIG. 1, the pressure in the crank chamber 201 of the engine 200 is introduced into the pulse chamber 120 through the pressure introduction passage 1121.

[0061] The engine 200 of the present disclosure can be used for various applications. For example, it can be used as a drive source for sprayers, blowers, brush cutters, etc. that can be carried by a person and operate outdoors. All of them are usually driven at a certain rotational speed. In the above description, it was explained that the range of pressure fluctuation in the crank chamber 201 is 5 kPa or more, or about 10 kPa. However, specifically, the pressure fluctuation in the crank chamber 201 changes according to the rotational speed of the engine 200. In a high-speed rotation state where the rotational speed is 10,000 revolutions per minute or more, the pressure in the crank chamber 201 fluctuates from about -20 kPa to about -30 kPa. The fluctuation range in this case is about 10 kPa.

[0062] On the other hand, in the low rotation state where the rotation speed is about 2,000 revolutions per minute, the pressure fluctuation in the crank chamber 201 becomes larger. Specifically, the pressure in the crank chamber 201 decreases from minus 30 kilopascals to minus 50 kilopascals. And when the pressure in the crank chamber 201 rises, it becomes about 10 kilopascals above atmospheric pressure. Therefore, in the low rotation range of the engine 200, the pressure fluctuation range in the crank chamber 201 becomes 60 kilopascals at maximum, which is considerably larger than 10 kilopascals during high-speed rotation.

[0063] In the other embodiments shown in FIGS. 10 to 12, on the premise that the width of the pressure fluctuation in the pulse chamber 120 changes according to the rotation speed of the engine 200, the pressure fluctuation in the pulse chamber 120 is surely transmitted to the mixing pump chamber 160 even in a state where the width of the pressure fluctuation is small. Therefore, in the other embodiments, the auxiliary diaphragm 190 is disposed on a surface of the surface forming the mixing pump chamber 160 other than the surface on which the diaphragm 170 is disposed.

[0064] Specifically, the auxiliary diaphragm 190 is disposed so as to block the atmospheric pressure hole 191 communicating with the mixing pump chamber 160 of the lower housing 150. Also, the outer periphery of the auxiliary diaphragm 190 is held by a holding plate 193 having an atmospheric pressure opening 192. And the holding plate 193 is fixed to the lower housing 150 by holding bolts 194. Therefore, the auxiliary diaphragm 190 receives the pressure in the mixing pump chamber 160 through the atmospheric pressure hole 191 on one surface thereof, and the other surface receives the atmospheric pressure through the atmospheric pressure opening 192. Here, since the atmospheric pressure is constant, the auxiliary diaphragm 190 will be displaced according to the pressure fluctuation in the mixing pump chamber 160.

[0065] As shown in FIG. 12, the auxiliary diaphragm 190 is arranged in parallel with the diaphragm 170. This is to enable the auxiliary diaphragm 190 to be arranged in the lower housing 150 even when the area of the auxiliary diaphragm 190 approaches the area of the diaphragm 170. This is because the auxiliary diaphragm 190 can function regardless of which surface forming the mixing pump chamber 160 it is arranged on. However, it is desirable to arrange the auxiliary diaphragm 190 in parallel with the diaphragm 170 in order to increase the area of the auxiliary diaphragm 190. By increasing the pressure-receiving area of the auxiliary diaphragm 190, the auxiliary diaphragm 190 is more likely to displace in response to the displacement of the diaphragm 170. As described above, the diaphragm 170 has a disk shape with a bent portion 174. In contrast, the auxiliary diaphragm 190 has a flat circular shape without a bent portion. Therefore, the displacement amount of the auxiliary diaphragm 190 is smaller than that of the diaphragm 170.

[0066] When the pressure fluctuation in the pulse chamber 120 is large, the displacement width of the diaphragm 170 is also large. Therefore, the volume fluctuation in the mixing pump chamber 160 is also large, and it is easy to open and close the inlet check valve 180 and the outlet check valve 181 to allow gasoline or the mixture to flow. However, when the pressure fluctuation in the pulse chamber 120 is small, the fluctuation width of the diaphragm 170 also becomes small. As a result, the volume fluctuation in the mixing pump chamber 160 also becomes small, and the pressure change in the mixing pump chamber 160 also decreases. Furthermore, as a result of the decrease in the pressure change, the functions of sucking gasoline and discharging the mixture by the mixing pump chamber 160 also deteriorate.

[0067] In other embodiments, the inlet check valve 180 and the outlet check valve 181 adopt a structure including the flat piston valve 187 shown in FIGS. 7 and 11. That is, a structure is adopted 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 even less pressure fluctuation compared to the duckbill shown in FIGS. 1 and 4.

[0068] In other embodiments, further, by providing the auxiliary diaphragm 190, it is easier to cause the pumping action of the mixing pump chamber 160. As described above, the auxiliary diaphragm 190 is displaced in accordance with the displacement of the diaphragm 170. Therefore, the volume fluctuation of the mixing pump chamber 160 can be achieved by the cooperation of the diaphragm 170 and the auxiliary diaphragm 190. In other words, even when it is insufficient to generate the flow of gasoline or the mixture in the mixing pump chamber 160 only with the diaphragm 170, the flow of fluid is likely to occur in the mixing pump chamber 160. This is because the cooperation of the diaphragm 170 and the auxiliary diaphragm 190 in displacement suppresses the occurrence of stagnation in the fluid flow in the mixing pump chamber 160.

[0069] Furthermore, in other words, in the description of the illustrated embodiment of FIG. 1 above, the pressure in the mixing pump chamber 160 was assumed to be substantially atmospheric pressure. However, strictly speaking, the pressure in the mixing pump chamber 160 of the illustrated embodiment of FIG. 1 is not constant at atmospheric pressure. This is because the flow resistance of gasoline or the mixture, and the flow resistances of the inlet check valve 180 and the outlet check valve 181 are applied to the mixing pump chamber 160. On the other hand, in other embodiments, since the atmospheric pressure hole 191 is opened in the lower housing 150, the pressure in 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 in the mixing pump chamber 160 at atmospheric pressure. Since the pressure in the mixing pump chamber 160 can be maintained at atmospheric pressure by the auxiliary diaphragm 190, gasoline or oil flows more easily in accordance with the displacement of the diaphragm 170.

[0070] In any case, the main body that generates the fluid flow in the mixing pump chamber 160 is the diaphragm 170. The auxiliary diaphragm 190 only assists the behavior of the diaphragm 170. Therefore, as described above, the displacement amount of the auxiliary diaphragm 190 is smaller than that of the diaphragm 170. Even with a small displacement amount, the displacement of the auxiliary diaphragm 190 maintains the pressure in the mixing pump chamber 160 at atmospheric pressure, suppressing the stagnation of the fluid flow.

[0071] Not limited to the embodiment shown in FIG. 12, in the above-described embodiments shown in FIGS. 1, 8, etc., a restriction mechanism support spring 133 is provided for the oil restriction mechanism 130. It is desirable to be able to stabilize the behavior of the oil restriction piston 132. However, it is possible to abolish the restriction mechanism support spring 133 as necessary.

[0072] The same applies to the upper diaphragm support spring 112 and the lower diaphragm support spring 152. In order 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. It is also possible to abolish the upper diaphragm support spring 112 and the lower diaphragm support spring 152 for reasons such as cost reduction and improvement of assemblability.

[0073] Also, in the above example, the gasoline mixture discharged from the mixture pump 100 is injected from the injector 220 into the engine 200. However, the injector is not an essential element. The gasoline mixture from the mixture pump 100 may be supplied to the intake passage 206 of the engine 200.

[0074] As the oil restriction mechanism 130, in the above example, an oil restriction piston 132 etc. are used. It is a desirable embodiment for restricting the supply of oil to the diffusion chamber 164. However, the oil restriction mechanism 130 only needs to be able to restrict the supply amount of oil, and it is also possible to restrict the supply amount by arranging an orifice in the oil supply passage 163 or the like.

[0075] Furthermore, the materials described above are an example of the present disclosure. For example, it is also possible to make the upper housing 110 and the lower housing 150 of the embodiments of FIGS. 1 and 2 made of metal in the same way as the embodiments shown in FIGS. 8 and 9. Also, the sizes described above are also an example, and it is possible to make a larger mixture pump 100 or a smaller mixture pump 100 according to the required engine specifications.

[0076] Furthermore, as an application of the mixture pump 100, supplying a mixture of gasoline and oil to a two-stroke engine is a desirable example of use in the present disclosure. However, the mixture pump 100 of the present disclosure is not limited to two-stroke engines as a pump that mixes and supplies two types of liquids.

Explanation of Signs

[0077] 100 Mixture pump 120 Pulse chamber 130 Oil restriction mechanism 160 Mixing pump chamber 161 Diffusion port 162 Gasoline supply passage 163 Oil supply passage 164 Diffusion chamber 165 Mixture outlet passage 170 Diaphragm 180 Inlet check valve 181 Outlet check valve 190 Auxiliary diaphragm

Claims

1. A pulse chamber (120) that receives external pulsations and has a fluctuating internal pressure, a diaphragm (170) that closes the pulse chamber and displaces in response to the pressure fluctuations in the pulse chamber, a mixing pump chamber (160) that is disposed opposite the pulse chamber with the diaphragm therebetween and has a fluctuating internal volume in response to the displacement of the diaphragm, a first liquid inlet passage (162) through which a first liquid flows into the mixing pump chamber, an inlet check valve (180) that is disposed in the first inlet passage, 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) that supplies a second liquid to the mixing pump chamber, a diffusion port (161) that is formed at an end of the second liquid supply passage on the mixing pump chamber side and has an opening area narrower than that of the first liquid inlet passage, a diffusion chamber (164) that is formed on the second liquid supply passage side of the diffusion port and diffuses the second liquid into the first liquid, a second liquid restricting mechanism (130) that is disposed on the second liquid supply passage side of the diffusion chamber and restricts the amount of the second liquid flowing from the second liquid supply passage into the diffusion chamber, a mixed liquid outlet passage (165) through which a mixed liquid of the first liquid and the second liquid flows out of the mixing pump chamber, an outlet check valve (181) that is disposed in the mixed liquid outlet passage, allows only the flow of the mixed liquid out of the mixing pump chamber, and prevents backflow into the mixing pump chamber, A mixed liquid pump (100), characterized by comprising the above.

2. The second liquid restricting mechanism includes a second liquid restricting passage (**131**) formed between the diffusion chamber and the second liquid supply passage, and a second liquid restricting piston (**132**) that is disposed in the second liquid restricting passage with a minute gap therebetween and is reciprocally movable within the second liquid restricting passage. The pressure in the diffusion chamber fluctuates in response to the volume fluctuations of the mixing pump chamber, and the second liquid restricting piston reciprocally moves 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 minute gap between the second liquid restricting piston and the second liquid restricting passage in response to the reciprocal movement of the second liquid restricting piston. The mixed liquid pump according to Claim 1, characterized by the above.

3. The second liquid restricting mechanism includes a restricting mechanism support spring (**133**) that supports the reciprocal movement of the second liquid restricting piston. The mixed liquid pump according to Claim 2, characterized by the above.

4. The opening area of the diffusion port is smaller than 20 percent of the opening area of the first liquid inlet passage. The liquid mixture pump according to claim 1, characterized in that.

5. The first liquid is gasoline and the second liquid is oil, The pulse chamber communicates with the crank chamber of the engine and receives the pressure pulsation in the crank chamber. From the liquid mixture outlet passage, a liquid mixture of gasoline and oil is supplied to the engine. The liquid mixture pump according to claim 1, characterized in that.

6. In the pulse chamber and the mixing pump chamber, diaphragm support springs (112, 152) for supporting the diaphragm are arranged. The liquid mixture pump according to claim 1, characterized in that.

7. An auxiliary diaphragm (190) is arranged on a surface other than the surface where the diaphragm is arranged among the surfaces forming the mixing pump chamber. One surface of this auxiliary diaphragm receives the pressure in the mixing pump chamber, and the other surface receives atmospheric pressure. The auxiliary diaphragm is displaced according to the pressure fluctuation in the mixing pump chamber. The liquid mixture pump according to claim 1, characterized in that.

8. The auxiliary diaphragm is arranged in parallel with the diaphragm and is displaced according to the displacement of the diaphragm. The liquid mixture pump according to claim 7, characterized in that.

9. The diaphragm has a disk shape with a bent portion, and the auxiliary diaphragm has a flat circular shape without a bent portion. The displacement amount of the auxiliary diaphragm is smaller than that of the diaphragm. The liquid mixture pump according to claim 7, characterized in that.

10. The inlet check valve and the outlet check valve include a check valve seat (184), a check valve body (182, 185, 187) for opening and closing the check valve seat, and a check valve spring (183) for biasing the check valve body toward the check valve seat side. The liquid mixture pump according to claim 1, characterized in that.

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