Patent Grant
11795945
This application claims the priority benefit of Japan application serial no. 2021-073773, filed on Apr. 26, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
The disclosure relates to a pump device that sucks fluid, pressurizes it, and discharges it, and more particularly to a pump device that includes an inner rotor and an outer rotor and is applied to a cylinder block of an internal combustion engine, a fluid device, or the like.
As a conventional pump device, a trochoid pump is known which includes a casing having a suction port and a discharge port, an inner rotor and an outer rotor as a pump unit housed in an accommodation space of the casing, and a pump shaft that rotates integrally with the inner rotor, and which pressurizes and supplies the hydraulic oil of an engine (see, for example, Patent Literature 1).
In this trochoid pump, the outer rotor rotates in conjunction with the rotation of the pump shaft and the inner rotor, and the gap (pump chamber) between the inner and outer teeth of both repeatedly expands and contracts, whereby the suction stroke for sucking the hydraulic oil and the pressurization and discharge stroke for pressurizing and discharging the sucked hydraulic oil are continuously repeated.
In this pump operation, in particular, when the rotation of the pump shaft becomes high, the suction resistance of the hydraulic oil increases, and when the suction stroke is completed, the inside of the pump chamber becomes a negative pressure state. Then, at the moment when the pump chamber in which the suction stroke is completed communicates with the discharge port side, the hydraulic oil in the pump chamber in the previous pressurization and discharge stroke flows back, and then the backflow stops and the forward flow occurs.
Due to this backflow and forward flow phenomenon, the hydraulic pressure of the hydraulic oil in the pump chamber in the pressurization and discharge stroke causes an increase in hydraulic pressure fluctuation (hydraulic amplitude) that repeatedly decreases and increases as the pump shaft rotates; as a result, it causes noise and vibration. Further, when the negative pressure becomes excessive, problems such as impact noise due to cavitation and erosion of the rotor occur.
In addition, in order to suppress the hydraulic amplitude with the same discharge amount, it is conceivable to adopt an inner rotor and an outer rotor having a large number of teeth to divide the discharge into smaller parts and increase the number of discharges. However, this leads to an increase in the size of the entire pump. Further, it is also conceivable to adopt a method of arranging the pump unit in two stages and similarly performing discharges alternately to increase the number of discharges, but the number of parts increases, which leads to high cost and an increase in the size of the entire pump.
Further, as a conventional pump device, an oil pump device or a trochoid pump in which an outer rotor or an inner rotor is divided into multiple pieces to reduce noise has been proposed (for example, see Patent Literature 2 and Patent Literature 3).
However, such pump devices allow the backflow of the hydraulic oil and do not suppress the increase in hydraulic pressure fluctuation (hydraulic amplitude) caused by the backflow of the hydraulic oil.
The disclosure has been made in view of the above circumstances, and the disclosure solves the above-mentioned problems of the conventional technology and provides a pump device capable of suppressing hydraulic amplitude and reducing noise or vibration associated with hydraulic amplitude while simplifying the structure.
A pump device according to the disclosure includes: a housing which defines a suction port, a discharge port, and an accommodation chamber; and a pump unit which is arranged in the accommodation chamber and which defines a pump chamber that expands and contracts to exert a pumping action including a suction stroke and a pressurization and discharge stroke on a fluid. The housing includes an air introduction hole that is opened to introduce air into the pump chamber at a predetermined opening timing immediately before the suction stroke is completed.
In the above pump device, a configuration may be adopted in which the air introduction hole is closed at a predetermined closing timing after the suction stroke is completed.
In the above pump device, a configuration may be adopted in which the pump unit includes an inner rotor that rotates around a predetermined axis and an outer rotor that rotates in conjunction with the rotation of the inner rotor.
In the above pump device, a configuration may be adopted in which the housing includes the air introduction hole in a wall part on which an end surface of the inner rotor and an end surface of the outer rotor slide.
In the above pump device, a configuration may be adopted in which the air introduction hole is provided at a position where it is opened and closed by the end surface of the inner rotor.
In the above pump device, a configuration may be adopted in which the discharge port includes a deviated opening region that is opened in deviation toward an outer peripheral side region of the outer rotor to discharge a fluid pressurized by the pump chamber from the outer peripheral side region of the outer rotor away from the inner rotor for a predetermined period from the start of the pressurization and discharge stroke.
In the above pump device, a configuration may be adopted in which the inner rotor and the outer rotor are trochoid rotors having a trochoidal tooth profile of four blades and five nodes.
In the above pump device, a configuration may be adopted in which when a rotation angle of the inner rotor over a range of the suction stroke is Θ, and a rotation angle of the inner rotor from the opening timing to the completion of the suction stroke is ΔΘa, ΔΘa is set in a range of 0.08×Θ<ΔΘa<0.12×Θ.
In the above pump device, a configuration may be adopted in which when a rotation angle of the inner rotor over a range of the suction stroke is Θ, and a rotation angle of the inner rotor from the opening timing to the completion of the suction stroke is ΔΘa, and a rotation angle of the inner rotor from the completion of the suction stroke to the closing timing is ΔΘb, ΔΘa is set in a range of 0.08×Θ<ΔΘa<0.12×Θ, and ΔΘb is set in a range of 0.6×ΔΘa<ΔΘb<0.7×ΔΘa.
In the above pump device, a configuration may be adopted which further includes a check valve which allows only air flow introduced from the air introduction hole into the pump chamber.
In the above pump device, a configuration may be adopted in which the housing includes: a housing body in a bottomed tubular shape which defines the suction port, the discharge port, a joint wall to be joined to an application object, and the accommodation chamber; and a housing cover in a flat plate shape which is combined to the housing body to close the accommodation chamber, and the air introduction hole is provided in the housing cover.
In the above pump device, a configuration may be adopted in which the housing includes: a housing body in a bottomed tubular shape which defines the accommodation chamber; and a housing cover in a flat plate shape which defines the suction port, the discharge port, and a joint wall to be joined to an application object, and which is combined to the housing body to close the accommodation chamber, and the air introduction hole is provided in the housing body.
Effects
According to the pump device having the above configuration, it is capable of suppressing hydraulic amplitude and reducing noise or vibration associated with hydraulic amplitude while simplifying the structure.
Hereinafter, embodiments of the disclosure will be described with reference to the accompanying drawings.
A pump device M1 according to the first embodiment is applied to an internal combustion engine E as an application object.
Here, as shown in
As shown in
The housing body 10 is formed in a bottomed tubular shape using a metal material such as steel, cast iron, sintered steel, aluminum alloy, or the like, and as shown in
As shown in
The outer peripheral wall 12 protrudes from the outer edge region of the joint wall 11 in a tubular shape in the axis S direction to define an annular end surface 12a.
The accommodation chamber 13 is a space defined by the joint wall 11 and the outer peripheral wall 12, and rotatably accommodates the pump unit Pu.
Further, as shown in
The arc surface 13a slidably supports an outer peripheral surface 53 of the outer rotor 50 forming a part of the pump unit Pu. Further, the inner edge part of the arc surface 13a also functions as a fitting recess into which a fitting protrusion 22 of the housing cover 20 is fitted.
The inlay part 14 protrudes outward from the joint wall 11 in the axis S direction and is formed in a cylindrical shape centered on the axis S, and is closely fitted to the fitting recess 4 of the engine main body 1.
As shown in
As shown in
The bearing hole 17 is formed in a cylindrical shape centered on the axis S inside the inlay part 14 to rotatably support a one-end-side region 31 of the rotation shaft 30.
The three insertion holes 18 are for inserting the bolts B to be screwed into the screw holes 7 of the engine main body 1, and are formed to penetrate from the end surface 12a to the outer wall surface 11a in the axis S direction.
The one screw hole 19 is formed in the end surface 12a for screwing the screw b that connects the housing cover 20 to the housing body 10.
The housing cover 20 is combined to the housing body 10 to close the accommodation chamber 13 of the housing body 10, and is formed in a flat plate shape using a material such as steel, cast iron, sintered steel, or an aluminum alloy.
Then, as shown in
The connection wall 21 is formed as a flat wall perpendicular to the axis S and is closely combined to the end surface 12a of the housing body 10.
The fitting protrusion 22 is formed in a disk shape near the center of the housing cover 20 to protrude from the connection wall 21 in the axis S direction with the axis S1 as the center, and defines an outer peripheral surface 22a and an inner wall surface 22b. The outer peripheral surface 22a is fitted to the inner edge part of the arc surface 13a of the housing body 10. The inner wall surface 22b is in close contact with end surfaces 42 and 52 of the pump unit Pu.
The bearing hole 23 is formed in a cylindrical shape centered on the axis S to rotatably support an other-end-side region 32 of the rotation shaft 30.
The annular protrusion 24 is formed in a cylindrical shape around the bearing hole 23 to protrude outward in the axis S direction in order to increase the mechanical strength.
The three insertion holes 25 are for inserting the bolts B to be screwed into the screw holes 7 of the engine main body 1, and are formed as circular holes penetrating in the axis S direction at positions corresponding to the three insertion holes 18 of the housing body 10.
The one circular hole 26 is for passing the screw b that connects the housing cover 20 to the housing body 10, and is formed near the one insertion hole 25.
The air introduction hole 27 is formed as a circular hole penetrating in the axis S direction in the wall part located in the region of the annular protrusion 24 and in the region of the inner wall surface 22b on which the inner rotor 40 slides in order to introduce the outside air into the pump chamber Pc defined by the pump unit Pu.
Further, the air introduction hole 27 is opened by the end surface 42 of the inner rotor 40 at a predetermined opening timing immediately before the suction stroke by the pump unit Pu is completed, and is closed by the end surface 42 of the inner rotor 40 at a predetermined closing timing after the suction stroke is completed.
As described above, the housing H includes: the housing body 10 in a bottomed tubular shape that defines the suction port 15, the discharge port 16, the joint wall 11 to be joined to the internal combustion engine E which is the application object, and the accommodation chamber 13; and the housing cover 20 in a flat plate shape that is combined to the housing body 10 to close the accommodation chamber 13; and the air introduction hole 27 is provided in the housing cover 20.
As described above, since the air introduction hole 27 is provided in the housing H in the region opposite to the side to be joined to the application object, there is no obstacle on the outside of the air introduction hole 27 and air (outside air) can be smoothly introduced into the pump chamber Pc.
The rotation shaft 30 is formed in a columnar shape extending in the axis S direction using a steel material or the like; the one-end-side region 31 of the rotation shaft 30 is fitted into the bearing hole 17 of the housing body 10, and the other-end-side region 32 of the rotation shaft 30 is fitted into the bearing hole 23 of the housing cover 20, and the rotation shaft 30 is rotatably supported around the axis S.
In
Actually, the rotation shaft 30 is formed to be connected to a driven rotating body such as a gear, a sprocket, or a pulley at the other-end-side region 32 protruding from the housing cover 20, for example, when the driving force of the driving rotating body of the internal combustion engine is transmitted, or the rotation shaft 30 is formed to be connected to the driving rotating body directly or via a transmission member at the other-end-side region 32, for example, when the driving force of the driving rotating body (such as a rotor or a driving shaft) of the electric motor is transmitted.
The rotation shaft 30 is formed to be directly connected to the driving rotating body at the one-end-side region 31 protruding from the joint wall 11 of the housing body 10, for example, when the driving force of the driving rotating body of the internal combustion engine is transmitted.
In this embodiment, as shown in
The pump unit Pu is arranged in the accommodation chamber 13 of the housing H, defines the pump chamber Pc that expands and contracts to exert a pumping action including a suction stroke and a pressurization and discharge stroke on the hydraulic oil as a fluid, and is configured as a four-blade five-node trochoid rotor including the inner rotor 40 and the outer rotor 50.
The inner rotor 40 is formed as an external gear having a trochoidal curved tooth profile by using a metal material such as steel or sintered steel. Then, as shown in
Further, the inner rotor 40 rotates integrally with the rotation shaft 30 in the direction of the arrow R about the axis S.
The outer rotor 50 is formed as an internal gear having a tooth profile that can mesh with the inner rotor 40 by using a metal material such as steel or sintered steel. Then, as shown in
The outer peripheral surface 53 slidably contacts the arc surface 13a of the housing body 10.
The five protrusions 54 and the five recesses 55 are formed to partially mesh with the four protrusions 44 and the four recesses 45 of the inner rotor 40.
Then, the outer rotor 50 rotates in conjunction with the rotation of the inner rotor 40 that rotates about the axis S and rotates about the axis S1 in the same direction as the inner rotor 40 as shown in
Further, when the inner rotor 40 and the outer rotor 50 partially mesh and rotate, the pump chamber Pc that expands and contracts is defined between the two, and the pumping action including the suction stroke and the pressurization and discharge stroke is continuously performed.
Next, the operation of the pump device M1 will be described with reference to
First, as shown in
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ1 (here, about 90 degrees), the hydraulic oil is being sucked from the suction port 15 into the pump chamber Pc (suction stroke).
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ2 (here, about 150 degrees), the hydraulic oil is being further sucked from the suction port 15 into the pump chamber Pc (suction stroke). Further, in this state, the pump chamber Pc becomes close to the air introduction hole 27, but the end surface 42 of the inner rotor 40 closes the air introduction hole 27.
Subsequently, as shown in
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ4 (here, about 172 degrees), it is just before the completion of the suction stroke in which the hydraulic oil is sucked from the suction port 15 to the pump chamber Pc, and the suction port 15 is squeezed, and the passage resistance increases. Therefore, when the rotation shaft 30 rotates at a particularly high rotation speed, the inflow of hydraulic oil into the pump chamber Pc cannot catch up, and the atmosphere in the pump chamber Pc is in a state of having a large negative pressure.
Immediately before the completion of this suction stroke, the end surface 42 of the inner rotor 40 is disengaged from the air introduction hole 27, and the air introduction hole 27 is opened. Therefore, due to the negative pressure of the pump chamber Pc, the outside air begins to be sucked into the pump chamber Pc through the air introduction hole 27.
Then, when the inner rotor 40 rotates to the position of the rotation angle θ5 (here, about 185 degrees), the suction stroke in which the hydraulic oil is sucked from the suction port 15 into the pump chamber Pc becomes closer to the completion point, and the air introduction hole 27 is still in an open state, and due to the negative pressure of the pump chamber Pc, the outside air continues to flow into the pump chamber Pc by the action of inertial force. As a result, the negative pressure of the pump chamber Pc is reduced.
Further, as shown in
At this time, the air introduction hole 27 is still open, and the outside air is in a state of flowing into the pump chamber Pc by the action of inertial force, and the negative pressure in the pump chamber Pc is sufficiently reduced in the process up to this point.
Further, the pump chamber Pc begins to communicate with the discharge port 16 in a narrow region, and the hydraulic oil in the pump chamber Pc begins to flow toward the discharge port 16 (at the start of the pressurization and discharge stroke).
In this way, when the suction stroke is completed and the process shifts to the pressurization and discharge stroke, the negative pressure in the pump chamber Pc is relieved by the introduced outside air (air), and the backflow of hydraulic oil in the pump chamber Pc in the previous stroke is suppressed or prevented. Further, since the backflow is suppressed or prevented, the increase in pressure due to the forward flow after the backflow is also suppressed or prevented.
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ7 (here, about 205 degrees), the air introduction hole 27 is closed by the end surface 42 of the inner rotor 40. That is, the air introduction hole 27 is closed at a predetermined closing timing (rotation angle θ7) after the suction stroke is completed (rotation angle θ6). Then, the hydraulic oil in the pump chamber Pc is discharged from the discharge port 16 while being pressurized (pressurization and discharge stroke).
Subsequently, the inner rotor 40 rotates to the position of the rotation angle θ11 via the position of the rotation angle θ8, the position of the rotation angle θ9, and the position of the rotation angle θ10, as shown in
Here, the description has been made focusing on one protrusion 44, but in reality, the pump chambers Pc defined behind the four protrusions 44 each perform the same operation (pumping action). Therefore, the suction stroke and the pressurization and discharge stroke are continuously performed for four times while the rotation shaft 30 makes one rotation.
In the first embodiment, the opening timing at which the air introduction hole 27 is opened is set to the rotation angle θ4 about 20 degrees before the rotation angle θ6 at which the suction stroke is completed.
Specifically, when the rotation angle (rotation angle θ6−rotation angle θ0) of the inner rotor 40 over the range of the suction stroke is set to Θ, and the rotation angle (rotation angle θ6-rotation angle θ4) of the inner rotor 40 from the opening timing (rotation angle θ4) to the completion of the suction stroke (rotation angle θ6) is set to ΔΘa, Θ=192 degrees, ΔΘa=192−172=20 degrees, and ΔΘa=0.1×Θ.
It is preferable that ΔΘa is set in the range of 0.08×Θ<ΔΘa<0.12×Θ in consideration of the variation in assembly of parts and the allowable angle range in which air is efficiently introduced.
That is, the rotation angle ΔΘa of the inner rotor 40 from the opening timing to the completion of the suction stroke is very small with respect to the rotation angle Θ in the range of the suction stroke, and the opening timing is set before the completion of the suction stroke by about 10% of the rotation angle in the range of the suction stroke.
In other words, the opening timing at which the air introduction hole 27 is opened is set immediately before the suction stroke is completed.
Further, when the rotation angle (rotation angle θ7−rotation angle θ6) of the inner rotor 40 from the completion of the suction stroke (rotation angle θ6) to the closing timing (rotation angle θ7) at which the air introduction hole 27 is closed is set to ΔΘb, ΔΘb=205−192=13 degrees, and ΔΘb=0.65×ΔΘa.
It is preferable that ΔΘb is set in the range of 0.6×ΔΘa<ΔΘb<0.7×ΔΘa in consideration of the variation in assembly of parts and the allowable angle range in which air is efficiently introduced.
In other words, the closing timing at which the air introduction hole 27 is closed is set when the discharge port 16 starts communicating with the pump chamber Pc after the suction stroke is completed.
As described above, according to the pump device M1 according to the first embodiment, by providing the air introduction hole 27 that is opened to introduce air into the pump chamber Pc at a predetermined opening timing (rotation angle θ4) immediately before the suction stroke is completed, in particular, the negative pressure in the pump chamber Pc can be relieved at high rotation speeds.
As a result, as shown in
In addition, it is possible to prevent the occurrence of cavitation due to excessive negative pressure and the occurrence of eclipse due to cavitation.
Further, by relieving the suction negative pressure, the drive torque for rotating the rotation shaft 30 can be reduced. In particular, at low temperature when the viscosity of the hydraulic oil is high, the shear torque of the hydraulic oil is relieved by introducing air into the hydraulic oil. As a result, the drive torque at low temperature can be reduced.
At the time of low rotation of the rotation shaft 30, the suction resistance is small, the negative pressure in the pump chamber Pc is also small, and the amount of air introduced from the air introduction hole 27 is small. On the other hand, at the time of high rotation of the rotation shaft 30, air is introduced in a state where the suction resistance is large and the suction of the hydraulic oil cannot catch up, and the rate of change in the volume of the pump chamber Pc in the region immediately before the completion of the suction stroke is less than or equal to 5%. Therefore, even if air is introduced, there is almost no difference between the intake amount and the discharge amount, and a desired discharge amount can be obtained.
Further, since the air introduction hole 27 is provided in the wall part of the housing H and is opened and closed by the end surface 42 of the inner rotor 40, compared with the case where a dedicated opening and closing valve is provided separately from the inner rotor 40, it is possible to achieve simplification of the structure, cost reduction, miniaturization, and the like.
Further, since the air introduction hole 27 is provided in the flat plate-shaped housing cover 20 configuring the housing H, it is only necessary to perform a hole drilling process, and the hole drilling process can be easily performed.
The pump device M2 according to the second embodiment includes a housing body 110 and a housing cover 20 as a housing H, a rotation shaft 30 centered on a predetermined axis S, an inner rotor 40 and an outer rotor 50 as a pump unit Pu, and a screw b for fastening the housing cover 20 to the housing body 110.
The housing body 110 is formed in a bottomed tubular shape using a metal material such as steel, cast iron, sintered steel, aluminum alloy, or the like, and includes a joint wall 11, an outer peripheral wall 12, an accommodation chamber 13, an inlay part 14, a suction port 15, a discharge port 116, a bearing hole 17, three insertion holes 18, and one screw hole 19.
As shown in
Then, in the rotation direction R of the rotation shaft 30, the deviated opening region 116a occupies the first half region of the discharge port 116, and the enlarged opening region 116b occupies the second half region of the discharge port 116.
That is, the discharge port 116 is configured to include the deviated opening region 116a that is opened in deviation toward the outer peripheral side region to discharge the hydraulic oil pressurized by the pump chamber Pc from the outer peripheral side region of the outer rotor 50 away from the inner rotor 40 for a predetermined period from the start of the pressurization and discharge stroke.
Next, the operation of the pump device M2 will be described with reference to
First, as shown in
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ1 (here, about 90 degrees), the hydraulic oil is being sucked from the suction port 15 into the pump chamber Pc (suction stroke).
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ2 (here, about 150 degrees), the hydraulic oil is being further sucked from the suction port 15 into the pump chamber Pc (suction stroke). Further, in this state, the pump chamber Pc becomes close to the air introduction hole 27, but the end surface 42 of the inner rotor 40 closes the air introduction hole 27.
Subsequently, as shown in
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ4 (here, about 172 degrees), it is just before the completion of the suction stroke in which the hydraulic oil is sucked from the suction port 15 to the pump chamber Pc, and the suction port 15 is squeezed, and the passage resistance increases. Therefore, when the rotation shaft 30 rotates at a particularly high rotation speed, the inflow of hydraulic oil into the pump chamber Pc cannot catch up, and the atmosphere in the pump chamber Pc is in a state of having a large negative pressure.
Immediately before the completion of this suction stroke, the end surface 42 of the inner rotor 40 is disengaged from the air introduction hole 27, and the air introduction hole 27 is opened. Therefore, due to the negative pressure of the pump chamber Pc, the outside air begins to be sucked into the pump chamber Pc through the air introduction hole 27.
Then, when the inner rotor 40 rotates to the position of the rotation angle θ5 (here, about 185 degrees), the suction stroke in which the hydraulic oil is sucked from the suction port 15 into the pump chamber Pc becomes closer to the completion point, and the air introduction hole 27 is still in an open state, and due to the negative pressure of the pump chamber Pc, the outside air continues to flow into the pump chamber Pc by the action of inertial force. As a result, the negative pressure of the pump chamber Pc is reduced.
Further, as shown in
At this time, the pump chamber Pc does not communicate with the discharge port 116 and is in a closed partition region. Further, the air introduction hole 27 is still open, and the outside air is in a state of flowing into the pump chamber Pc by the action of inertial force, and the negative pressure in the pump chamber Pc is sufficiently reduced in the process up to this point.
In this way, the negative pressure in the pump chamber Pc is relieved by the introduced outside air (air) before the suction stroke is completed and the process shifts to the pressurization and discharge strokes.
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ7 (here, about 205 degrees), the air introduction hole 27 is closed by the end surface 42 of the inner rotor 40. Further, the pump chamber Pc begins to communicate with the deviated opening region 116a of the discharge port 116 in a narrow region, and the hydraulic oil in the pump chamber Pc begins to be discharged toward the discharge port 116 (at the start of the pressurization and discharge stroke).
At the start of this pressurization and discharge stroke, the negative pressure in the pump chamber Pc has already been relieved, so the backflow of hydraulic oil in the pump chamber Pc in the previous stroke is suppressed or prevented. Further, since the backflow is suppressed or prevented, the increase in pressure due to the forward flow after the backflow is also suppressed or prevented.
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ8, the hydraulic oil in the pump chamber Pc is discharged while being pressurized from the deviated opening region 116a of the discharge port 116 to the downstream side of the discharge port 116. That is, the hydraulic oil pressurized by the pump chamber Pc is discharged from the outer peripheral side region of the outer rotor 50 away from the inner rotor 40 (pressurization and discharge stroke). At this time, the mixed air (air bubbles) is gathered in the region adjacent to the recess 45 of the inner rotor 40 without being discharged from the discharge port 116 due to the centrifugal force.
Subsequently, as shown in
Subsequently, when the inner rotor 40 rotates to the position of the rotation angle θ9-3 via the position of the rotation angle θ9-2, the hydraulic oil in the pump chamber Pc is mainly discharged while being pressurized from the deviated opening region 116a to the downstream side of the discharge port 116, and is slightly discharged while being pressurized from the enlarged opening region 116b to the downstream side of the discharge port 116.
In this state, the mixed air (air bubbles) is crushed by pressure without being discharged from the discharge port 116 in a state of being gathered in the region adjacent to the recess 45 of the inner rotor 40 by the centrifugal force.
Subsequently, as shown in
In this state, the mixed air (air bubbles) is in a state of being gathered in the region adjacent to the recess 45 of the inner rotor 40 by the centrifugal force without being discharged from the discharge port 116, is crushed by pressure, melts into the hydraulic oil and almost disappears.
Subsequently, the inner rotor 40 rotates to the position of the rotation angle θ11 via the position of the rotation angle θ10. In this process, the hydraulic oil in the pump chamber Pc continues to be discharged from the discharge port 116 while being pressurized (pressurization and discharge stroke). Further, at the position of the rotation angle θ11, the position returns to the position of the rotation angle θ0 shown in
Here, the description has been made focusing on one protrusion 44, but in reality, the pump chambers Pc defined behind the four protrusions 44 each perform the same operation (pumping action). Therefore, the suction stroke and the pressurization and discharge stroke are continuously performed for four times while the rotation shaft 30 makes one rotation.
In the second embodiment, the opening timing at which the air introduction hole 27 is opened is set to the rotation angle θ4 about 20 degrees before the rotation angle θ6 at which the suction stroke is completed.
That is, the opening timing at which the air introduction hole 27 is opened is set immediately before the suction stroke is completed.
Further, the closing timing at which the air introduction hole 27 is closed is set when the deviated opening region 116a of the discharge port 116 starts communicating with the pump chamber Pc after the suction stroke is completed.
In particular, since the discharge port 116 is formed to include the deviated opening region 116a, from the start of the pressurization and discharge stroke to a predetermined period, the hydraulic oil pressurized by the pump chamber Pc can be discharged from the outer peripheral side region of the outer rotor 50 away from the inner rotor 40 without discharging the introduced air (air bubbles). As a result, the introduced air (air bubbles) can be used as a damper means for absorbing and attenuating the high pressure side of the hydraulic pressure fluctuation, and the hydraulic amplitude can be efficiently reduced.
As described above, according to the pump device M2 according to the second embodiment, as in the first embodiment, the hydraulic amplitude ΔP of the hydraulic oil can be reduced as compared with the conventional product, and the vibration and noise associated with the hydraulic amplitude ΔP can also be reduced. In addition, it is possible to prevent the occurrence of cavitation due to excessive negative pressure and the occurrence of eclipse due to cavitation, and it is possible to achieve simplification of the structure, cost reduction, miniaturization and the like.
Further, by relieving the suction negative pressure, the drive torque for rotating the rotation shaft 30 can be reduced. In particular, at low temperature when the viscosity of the hydraulic oil is high, the shear torque of the hydraulic oil is relieved by introducing air into the hydraulic oil. As a result, the drive torque at low temperature can be reduced.
The pump device M3 according to the third embodiment includes a housing body 10 and a housing cover 20 as a housing H, a rotation shaft 30 centered on a predetermined axis S, an inner rotor 40 and an outer rotor 50 as a pump unit Pu, a check valve 60, and a screw b for fastening the housing cover 20 to the housing body 10.
The check valve 60 is arranged, for example, on the downstream side of the air introduction hole 27 of the housing cover 20. Then, the check valve 60 opens when the pressure in the pump chamber Pc becomes a negative pressure of a predetermined level or less, allows a one-way air flow in which the outside air flows into the pump chamber Pc through the air introduction hole 27, and blocks the hydraulic oil from flowing out from the pump chamber Pc to the outside.
According to the pump device M3 according to the third embodiment, the same effects as those of the above-described embodiments can be achieved; in addition, even if the pressure in the pump chamber Pc rises, it is possible to reliably prevent the hydraulic oil from flowing out to the outside.
The pump device M4 according to the fourth embodiment includes a housing body 210 and a housing cover 220 as a housing H, a rotation shaft 30 centered on a predetermined axis S, an inner rotor 40 and an outer rotor 50 as a pump unit Pu, and a screw b for fastening the housing cover 220 to the housing body 210.
The housing body 210 is formed in a bottomed tubular shape using a metal material such as steel, cast iron, sintered steel, aluminum alloy, or the like, and includes a bottom wall 211, an outer peripheral wall 212, an accommodation chamber 213, a bearing hole 214, an annular protrusion 215, three insertion holes 216, one screw hole 217, and an air introduction hole 218.
The bottom wall 211 is formed as a flat wall perpendicular to the axis S, and defines an outer wall surface 211a and an inner wall surface 211b on which end surfaces 42 and 52 of the pump unit Pu slide in close contact with each other.
The outer peripheral wall 212 protrudes from the outer edge region of the bottom wall 211 in a tubular shape in the axis S direction to define an annular end surface 212a.
The accommodation chamber 213 is a space defined by the bottom wall 211 and the outer peripheral wall 212, and rotatably accommodates the pump unit Pu.
Further, as shown in
The arc surface 213a slidably supports an outer peripheral surface 53 of the outer rotor 50 forming a part of the pump unit Pu. Further, the inner edge part of the arc surface 213a also functions as a fitting recess into which a fitting protrusion 222 of the housing cover 220 is fitted.
The bearing hole 214 is formed in a cylindrical shape centered on the axis S to rotatably support an other-end-side region 32 of the rotation shaft 30.
The annular protrusion 215 is formed in a cylindrical shape around the bearing hole 214 to protrude outward in the axis S direction in order to increase the mechanical strength.
The three insertion holes 216 are for inserting the bolts B to be screwed into the screw holes 7 of the engine main body 1, and are formed to penetrate from the outer wall surface 211a to the end surface 212a in the axis S direction.
The one screw hole 217 is formed in the end surface 212a for screwing the screw b that connects the housing cover 220 to the housing body 210.
The air introduction hole 218 is formed as a circular hole penetrating in the axis S direction in the wall part located in the region of the annular protrusion 215 and in the region of the inner wall surface 211b on which the inner rotor 40 slides in order to introduce the outside air into the pump chamber Pc defined by the pump unit Pu.
Further, the air introduction hole 218 is opened by the end surface 42 of the inner rotor 40 at a predetermined opening timing immediately before the suction stroke by the pump unit Pu is completed, and is closed by the end surface 42 of the inner rotor 40 at a predetermined closing timing after the suction stroke is completed.
Here, since the air introduction hole 218 is provided on the wall part of the housing H and is opened and closed by the end surface 42 of the inner rotor 40, compared with the case where a dedicated opening and closing valve is provided separately from the inner rotor 40, it is possible to achieve simplification of the structure, cost reduction, miniaturization, and the like.
Further, since the air introduction hole 218 is provided in the bottom wall 211 of the bottomed tubular-shaped housing body 210 configuring the housing H, it is only necessary to perform a hole drilling process, and the hole drilling process can be easily performed.
The housing cover 220 is combined to the housing body 210 to close the accommodation chamber 213 of the housing body 210, and is formed in a flat plate shape using a material such as steel, cast iron, sintered steel, or an aluminum alloy.
The housing cover 220 includes a joint wall 221, a fitting protrusion 222, an inlay part 223, a suction port 224, a discharge port 225, a bearing hole 226, three insertion holes 227, and one circular hole 228.
The joint wall 221 is formed as a flat wall perpendicular to the axis S, and defines an outer wall surface 221a joined to the joint surface 3 of the engine main body 1 and an inner wall surface 221b joined to the end surface 212a of the housing body 210.
The fitting protrusion 222 is formed in a disk shape near the center of the housing cover 220 to protrude from the joint wall 221 in the axis S direction with the axis S1 as the center, and defines an outer peripheral surface 222a and an inner wall surface 222b. The outer peripheral surface 222a is fitted to the inner edge part of the arc surface 213a of the housing body 210. The end surfaces 41 and 51 of the pump unit Pu slidably come into close contact with the inner wall surface 222b.
The inlay part 223 protrudes outward from the joint wall 221 in the axis S direction and is formed in a cylindrical shape centered on the axis S, and is closely fitted to the fitting recess 4 of the engine main body 1.
The suction port 224 has the same shape as the suction port 15 according to the above-described embodiment, and as shown in
The discharge port 225 has the same shape as the discharge port 16 according to the above-described embodiment, and as shown in
The bearing hole 226 is formed in a cylindrical shape centered on the axis S inside the inlay part 223 to rotatably support a one-end-side region 31 of the rotation shaft 30.
The three insertion holes 227 are for inserting the bolts B to be screwed into the screw holes 7 of the engine main body 1, and are formed as circular holes penetrating in the axis S direction at positions corresponding to the three insertion holes 216 of the housing body 210.
The one circular hole 228 is for passing a screw b that connects the housing cover 220 to the housing body 210, and is formed near the one insertion hole 227.
As described above, the housing H includes the bottomed tubular housing body 210 which defines the accommodation chamber 213 and the flat plate-shaped housing cover 220 which defines the suction port 224, the discharge port 225, the joint wall 221 to be joined to the application object and which is combined to the housing body 210 to close the accommodation chamber 213; and the air introduction hole 218 is provided in the housing body 210.
As described above, since the air introduction hole 218 is provided in the housing H in the region opposite to the side to be joined to the application object, there is no obstacle on the outside of the air introduction hole 218 and air (outside air) can be smoothly introduced into the pump chamber Pc.
According to the pump device M4 according to the fourth embodiment, as in the above-described embodiments, the hydraulic amplitude ΔP of the hydraulic oil can be reduced as compared with the conventional product, and the vibration and noise associated with the hydraulic amplitude ΔP can also be reduced. In addition, it is possible to prevent the occurrence of cavitation due to excessive negative pressure and the occurrence of eclipse due to cavitation, and it is possible to achieve simplification of the structure, cost reduction, miniaturization and the like.
Further, by relieving the suction negative pressure, the drive torque for rotating the rotation shaft 30 can be reduced. In particular, at low temperature when the viscosity of the hydraulic oil is high, the shear torque of the hydraulic oil is relieved by introducing air into the hydraulic oil. As a result, the drive torque at low temperature can be reduced.
Further, in the pump device M4 according to the fourth embodiment, a discharge port having the same form as the discharge port 116 according to the second embodiment may be adopted, and the check valve 60 according to the third embodiment may be adopted.
In the above embodiments, the pump unit Pu including the trochoid rotors (inner rotor 40 and outer rotor 50) having a trochoidal tooth profile is shown as the pump unit exerting the pumping action, but the disclosure is not limited thereto.
For example, a rotor unit including an inner rotor and an outer rotor having a tooth profile other than the trochoidal tooth profile may be adopted. Further, the disclosure is not limited to the pump unit including the inner rotor and the outer rotor, and other positive displacement pump units may be adopted.
In the above embodiments, the inner rotor 40 and the outer rotor 50 configuring the pump unit Pu have been shown to be composed of four blades and five nodes forming a trochoidal tooth profile, but the disclosure is not limited thereto, and a configuration composed of other numbers may be adopted.
In the above embodiments, the end surface 42 of the inner rotor 40 is used to open and close the air introduction holes 27 and 218 provided in the housing H, but the disclosure is not limited thereto. The location of the air introduction hole may be changed, and the air introduction hole may be opened and closed by the end surface 52 of the outer rotor 50.
In the above embodiments, the housing cover 20 or the housing body 210 configuring the housing H is provided with the air introduction holes 27 and 218 by drilling holes, but a filter member for removing suspended matter in the outside air may be installed in the middle of the passage including the air introduction holes 27 and 218.
In the above embodiment, an internal combustion engine mounted on an automobile or the like is shown as an application object to which the pump devices M1, M2, M3 and M4 are applied, but the disclosure is not limited thereto, and it may be applied to a transmission or other lubricating equipment, or may be applied to a fluid equipment using fluids other than hydraulic oil.
In the above embodiments, the housing H of the pump devices M1, M2, M3, and M4 is provided with the joint walls 11 and 221 to be joined to the application object, but the disclosure is not limited thereto, and it may be applied to a system in which the fluid is sucked and discharged through a connecting pipe or the like, and may be arranged independently instead of being joined to the application object. In this case, the air introduction hole is not limited to the side opposite to the joint wall, and may be provided in a suitable region of the housing.
As described above, the pump device of the disclosure can suppress the hydraulic amplitude while achieving the simplification of the structure, and can also reduce the noise or vibration associated therewith. Therefore, not only can it be applied to an internal combustion engine of an automobile or a two-wheeled vehicle, but it can also be applied to other lubricating equipment, and it is also useful in fluid equipment that handles fluids other than hydraulic oil.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-073773 | Apr 2021 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20140356195 | Tojo | Dec 2014 | A1 |
| 20160186753 | Oda | Jun 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 102019120238 | Jan 2021 | DE |
| 2003293964 | Oct 2003 | JP |
| 2010053785 | Mar 2010 | JP |
| 2018105291 | Jul 2018 | JP |
| WO-2018198451 | Nov 2018 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20220341419 A1 | Oct 2022 | US |
