Patent ID: 12228134

DESCRIPTION OF EMBODIMENTS

Next, forms for carrying out the present invention are described with use of several embodiments.

Embodiment 1

A structure of a rotary-vane-type hydraulic pump that is Embodiment 1 of the present invention is shown below byFIG.7toFIG.24.FIG.7toFIG.12are diagrams describing a first structure example of Embodiment 1 and showing a result in which the flow rate fluctuation becomes zero.FIG.13toFIG.18are views used to describe the reason the flow rate fluctuation in the first structure example of Embodiment 1 becomes zero,FIG.19toFIG.22are diagrams and views showing a second structure example of Embodiment 1,FIG.23andFIG.24are a diagram and view showing a third structure example of Embodiment 1.

FIG.7is a front view showing a structure example of a rotary-vane-type hydraulic pump that is a first structure example of Embodiment 1 of the present invention in which five vanes and one suction and one discharge during one rotor rotation are in common with the related-art structure example inFIG.1but a cam ring profile is improved.FIG.8is a diagram showing how the vanes move in accordance with the rotor rotation angle in order to define the improved cam ring profile in the first structure example.FIG.9is a diagram showing a change of a front area of each working chamber in a suction stroke and a total area thereof in the first structure example inFIG.7.FIG.10is a diagram showing a change of a front area of each working chamber in a discharge stroke and a total volume thereof in the first structure example inFIG.7as functions of a rotor rotation angle.FIG.11is a diagram showing a pump flow-rate fluctuation pattern on the suction side of the first structure example that is a differential value of the total area inFIG.9by the rotor rotation angle.FIG.12is a diagram showing a pump flow-rate fluctuation pattern on the discharge side of the first structure example that is a differential value of the total area inFIG.10by the rotor rotation angle.

FIG.13is a view showing a front view of the cam ring profile, the rotor, each vane, a suction port, and a discharge port in a rotor rotation position in which the number of the suction working chambers is three and the number of the discharge working chambers is two in the first structure example inFIG.7and showing parts of the three suction working chambers and the two discharge working chambers seen from the front side with different hatchings.FIG.14is a view showing a portion surrounded by two line segments connecting a rotor center and each of two contact points between the cam ring and frontmost and rearmost vanes out of all of the vanes forming the three suction working chambers inFIG.13to each other, a cam-ring inner circumferential surface, and a circular arc of a rotor outer diameter, and a portion surrounded by two line segments connecting the rotor center and each of two contact points between the cam ring and frontmost and rearmost vanes out of all the vanes forming the two discharge working chambers to each other, the cam-ring inner circumferential surface, and the circular arc of the rotor outer diameter with different hatchings.FIG.15is a view showing each distal end portion of the vanes in the portion hatched on the suction working chamber side inFIG.14and similarly each distal end portion of the vanes in the hatched portion on the discharge working chamber side with different hatchings.

FIG.16is a view showing a front view of the cam ring profile, the rotor, each vane, the suction port, and the discharge port in another rotor rotation position in which the number of the suction working chambers is two and the number of the discharge working chambers is three in the first structure example inFIG.7and showing parts of the two suction working chambers and the three discharge working chambers seen from the front side with different hatchings.FIG.17is a view showing a portion surrounded by two line segments connecting the rotor center and each of two contact points between the cam ring and frontmost and rearmost vanes out of all of the vanes forming the two suction working chambers inFIG.16to each other, the cam-ring inner circumferential surface, and the circular arc of the rotor outer diameter, and a portion surrounded by two line segments connecting the rotor center and each of two contact points between the cam ring and frontmost and rearmost vanes out of all the vanes forming the three discharge working chambers to each other, the cam-ring inner circumferential surface, and the circular arc of the rotor outer diameter with different hatchings.FIG.18is a view showing each distal end portion of the vanes in the portion hatched on the suction working chamber side inFIG.17and similarly each distal end portion of the vanes in the hatched portion on the discharge working chamber side with different hatchings.

FIG.19is a diagram showing how vanes move in accordance with the rotor rotation angle in order to define a cam ring profile of a rotary-vane-type hydraulic pump that is a second structure example of Embodiment 1 of the present invention in which each working chamber performs a plurality of times of suction and discharge during one rotor rotation.FIG.20is a front view showing a cam ring profile, a rotor, each vane, a suction port, and a discharge port of the second structure example of Embodiment 1.FIG.21is a diagram showing a change of the front area of each working chamber that communicates with one suction port in the second structure example inFIG.19and the total area thereof as functions of the rotor rotation angle.FIG.22is a diagram showing a pump flow-rate fluctuation pattern from one suction port of the second structure example that is the differential value of the total volume inFIG.21by the rotor rotation angle.

FIG.23is a diagram showing how the vanes move in accordance with the rotor rotation angle in order to define a cam ring profile of a rotary-vane-type hydraulic pump that is a third structure example of Embodiment 1 of the present invention in which a circular arc interval of the cam ring profile is expanded.FIG.24is a front view showing a cam ring profile, a rotor, each vane, a suction port, and a discharge port of the third structure example of Embodiment 1.

InFIG.7that is the first structure example of Embodiment 1, as with the related-art structure example inFIG.1, a shaft member11, a rotor12, five vanes13, a cam ring14, and two side plates15,16are shown as main components. The vanes13also perform one advance and retreat movement within rotor slits12afor one rotation of the rotor12while distal ends thereof are pressed against a cam-ring inner circumferential surface14a.

Meanwhile, the profile of the cam-ring inner circumferential surface14ais different from the related-art structure example inFIG.1and the entirety is not one perfect circle. In the first structure example inFIG.7, the sectional shape of the distal end of the vane13is a circular arc with a small radius Rv, and a circular arc center point P0thereof is a fixed point on the vane and is on a line offset from the center of the rotor12to the opposite rotation side in a direction orthogonal to the direction of the rotor slit12aby Of. At this time, the profile of the cam-ring inner circumferential surface14acan be defined by showing how a direction distance L of the point P0from the rotor center O in the rotor slit12adirection changes when the shaft member11and the rotor12are rotated in a state in which the distal end of the vane13maintains a contact with the cam-ring inner circumferential surface14a.

FIG.8shows L described above as a function L(θr) of a rotor rotation angle θr. Regarding the rotor rotation angle θr, the rotor position when one of the rotor slits12abecomes parallel to an X-axis inFIG.7and opens to an outer circumference surface in the X-axis positive direction serves as a reference, and θr=0 is established in that position. Here, L(θr) represents the distance L described above of the vane13in the rotor slit12arotated from the reference position in the counterclockwise direction inFIG.7by θr.

InFIG.8, an example of a curve of L(θr) in the first structure example of Embodiment 1 is expressed by an interval of 0≤θr≤2π. This interval is formed by a first interval that is fixed at a minimum value Lmin, a second interval that is an increasing interval to a maximum value Lmax, a third interval that is fixed at the maximum value Lmax, a fourth interval that is a decreasing interval to the minimum value Lmin, and a fifth interval that is fixed at the minimum value Lminagain. Those intervals are smoothly connected to each other and indicate that the vane13performs the advance and retreat movement with a period of one rotation of the rotor. A change amount of θrin each of the intervals from the first interval to the fifth interval is expressed by symbols θ1, θ2, θ3, θ4, and θ5, where θ1=π/5) (36°, θ2=3π/5 (108°), θ3=2π/5 (72°), θ4=3π/5 (108°), θ5=π/5) (36°, and Lmin=21 mm, Lmax=26 mm are satisfied in this structure example. As with the related-art structure example inFIG.1, a rotor diameter Dr=46 mm, the number of vanes Nv=5, a vane distal-end circular-arc radius Rv=3 mm, a distal-end circular-arc-center offset Of=2 mm, and a vane thickness T=1.6 mm are satisfied in this structure example as well.

InFIG.8, L(θr) in the first interval of 0≤θr≤θ1, L(θr) in the third interval of θ1+θ2θr<θ1+θ2+θ3, and L(θr) in the fifth interval of θ1+θ2+θ3+θ4≤θr<2π are given as fixed values of Expression (1), Expression (2), and Expression (3), respectively.
[Expression 1]
L(θr)=Lmin(1)
in the first interval 0≤θr<θ1
[Expression 2]
L(θr)=Lmax(2)
in the third interval θ1+θ2≤θr<θ1+θ2+θ3
[Expression 3]
L(θr)=Lmin(3)
in the fifth interval θ1+θ2+θ3+θ4≤θr<2π

Profile intervals in which the vanes43perform a radial-direction movement in the rotor outer circumferential direction or the inner circumferential direction in accordance with the rotation of the rotor such as the second interval of θ1≤θr<θ1+θ2and the fourth interval of θ1+θ2+θ3≤θr<θ1+θ2+θ3+θ4inFIG.8are further divided into a first portion, a second portion, and a third portion continuously connected in order, and L(θr) in each portion is given by a functional form different from each other. The L(θr) obtained by connecting them has smooth connections to L(θr) in the first interval, L(θr) in the third interval, and L(θr) in the fifth interval as a result of a gradient dL/dθrbeing zero at a starting end of the first portion and a terminal end of the third portion; and L(θr) in each portion is smoothly connected to each other as a result of the gradient dL/dθrbeing the same values at a terminal end of the first portion and a starting end of the third portion and the gradient of the second portion being a fixed value equal to those same values.

In the second interval inFIG.8, a change amount of θrin a first portion is represented by γ1, a change amount of θrin a second portion is represented by γ2, a change amount of θrin a third portion is represented by γ3, and γ3and γ1are equal to each other. As combination examples of a functional form of L(θr) in which a smooth connection described above is realized, a combination of Expression (4) in the first portion, Expression (5) in the second portion, and Expression (6) in the third portion is conceived. As combination examples of a functional form of L(θr) in which a smooth connection described above is realized, a combination of Expression (7) in the first portion, Expression (8) in the second portion, and Expression (9) in the third portion is conceived in the fourth interval as well when the change amount of θrin the first portion is represented by γ1, the change amount of θrin the second portion is represented by 12, the change amount of θrin the third portion is represented by γ3, and γ3is equal to γ1. In the first structure example, the number of vanes Nv=5 is satisfied, and hence an angle α=2π/Nv=2π/5 (72°) between adjacent rotor slits is satisfied, γ1and γ3satisfy γ1=γ3=π/5 (36°) in both of the second interval and the fourth interval, γ2satisfies γ2=α−γ1, and γ2satisfies γ2=π/5 (36°) in both of the second interval and the fourth interval.

[Expression⁢4]L⁡(θr)=Lmax-Lmin2⁢(γ1+γ2)·(θr-θ1)-Lmax-Lmin2⁢(γ1+γ2)·γ12·sin⁡(2⁢π⁢θr-θ12⁢γ1)+Lmin(4)in the first portion θ1≤θr>θ1+γ1in the second interval

[Expression⁢5]L⁡(θr)=Lmax-Lmin2⁢(γ1+γ2)·(θr-θ1)-Lmax-Lmin2⁢(γ1+γ2)·γ1+Lmin(5)in the second portion θ1+γ1≤θr<θ1+γ1+γ2in the second interval

[Expression⁢6]L⁡(θr)=Lmax-Lmin2⁢(γ1+γ2)·(θr-θ1)-Lmax-Lmin2⁢(γ1+γ2)·γ12·sin⁡(2⁢π⁢θr-θ1-γ22⁢γ1)+Lmax-Lmin2⁢(γ1+γ2)·γ2+Lmin(6)in the third portion θ1+γ1+γ2≤θ1+γ2γ1+γ2in the second interval

[Expression⁢7]L⁡(θr)=-Lmax-Lmin2⁢(γ1+γ2)·(θr-θ1-θ2-θ3)+Lmax-Lmin2⁢(γ1+γ2)·γ1π·sin⁡(2⁢π⁢θr-θ1-θ2-θ32⁢γ1)+Lmax(7)in the first portion θ1+θ2+θ3≤θr<θ1+θ2+θ3+γ1in the fourth interval

[Expression⁢8]L⁡(θr)=-Lmax-Lmin2⁢(γ1+γ2)·(θr-θ1-θ2-θ3)+Lmax-Lmin2⁢(γ1+γ2)·γ1+Lmax(8)in the second portion θ1+θ2+θ3+γ1≤θr<θ1+θ2+θ3+γ1+γ2in the fourth interval

[Expression⁢9]L⁡(θr)=-Lmax-Lmin2⁢(γ1+γ2)·(θr-θ1-θ2-θ3)+Lmax-Lmin2⁢(γ1+γ2)·γ1π·sin⁡(2⁢π⁢θr-θ1-θ2-θ3-γ22⁢γ1)-Lmax-Lmin2⁢(γ1+γ2)·γ2+Lmax(9)in the third portion θ1+θ2+θ3+γ1+γ2≤θr<θ1+θ2+θ3+γ21+γ2in the fourth interval

The actual profile of the cam-ring inner circumferential surface14adefined by L(θr) is shown inFIG.7andFIG.13toFIG.16, a contact point of the distal end of the vane13in a boundary position of the intervals and the portions of θrinFIG.8is shown on the line thereof by a black point Pi-jor Pk-l-m. Here, Pi-jrepresents a contact point in a boundary between an i-th interval and a j-th interval of θr, and Pk-l-mrepresents a contact point in a boundary between a 1-th portion and an m-th portion in a k-th interval of θr. This also applies to explanatory diagrams and views of other embodiments and structure examples. The first interval and the fifth interval correspond to circular arc portions with a relatively small radius having a common center with the rotor42, and the third interval corresponds to a circular arc portion with a relatively great radius. Each the second interval and the fourth interval correspond to an interval in which the distance from the rotor center increases and an interval in which the distance from the rotor center decreases in order to smoothly connect the great and small circular arc portions. The actual profile of the cam-ring inner circumferential surface14ais not a trajectory of the vane distal-end circular-arc center point P0directly obtained from L(θr) and is an envelope on the outer side of a group of circles of which center is on the trajectory and which have the radius Rv.

A calculation result of the front area S of each working chamber in the suction stroke in the first structure example having this profile of the cam-ring inner circumferential surface is shown inFIG.9, and a calculation result of the front area S of each working chamber in the discharge stroke is shown inFIG.10as functions of the rotor rotation angle θr. As it can be understood fromFIG.7, one working chamber area increases and decreases once during one rotation in accordance with the change of the rotor rotation angle θr, the suction port is formed in a position that communicates with the working chamber in the interval of θrin which the distance L(θr) of each vane forming the working chamber from the rotor center starts to increase by the front vane and ends to increase by the rear vane, and the discharge port is formed in a position that communicates with the working chamber in the interval of θrin which the distance L(θr) of each vane forming the working chamber from the rotor center starts to decrease by the front vane and ends to decrease by the rear vane. The working chamber that communicates with the suction port is the working chamber in the suction stroke, and the working chamber that communicates with the discharge port is the working chamber in the discharge stroke.

One working chamber area S in the suction stroke inFIG.9is equivalent to an increasing portion of the increase and decrease of the working chamber area. One working chamber area S in the discharge stroke inFIG.10is equivalent to a decreasing portion of the increase and decrease of the working chamber area. In the structure example of Embodiment 1, the number of the vanes13Nv=5 is satisfied, and hence there are always five working chambers of which phases are shifted from each other by the angle α=2π/5 (72°) between the adjacent rotor slits. The calculation results of all of the working chamber areas S are all shown inFIG.9andFIG.10.

In each ofFIG.9andFIG.10, a calculation result of a total area St(θr) of a working chamber area S(θr) of each stroke in the position of θrthat is the horizontal axis is also shown. The number of the vanes13Nv=5 is satisfied in the first structure example of Embodiment 1. Therefore, in both of the drawings, there is a case where the number of the working chambers in each stroke is three and a case where the number of the working chambers in each stroke is two at one position of θr, and those areas S(θr) are indicated by S1to S3or S1to S2in the drawings. The total area St(θr) thereof changes in a stepwise manner at positions at which the number is switched, but change is made at a substantially fixed gradient in each interval in which the number is fixed. The change in the stepwise manner of the former is due to the starting and ending of communication between one working chamber and each port and is not a change of the working chamber total area St(θr) in a state of communicating with each port. Therefore, the total volume obtained by multiplying St(θr) by the thickness W of the cam ring that is the fixed value does not change in a state of communicating with each port, and the fluctuation of the pump flow rate is not affected on the suction side nor the discharge side. Meanwhile, in an interval in which St(θr) changes at a substantially fixed gradient, the volume of the working chamber that communicates with each port changes when the gradient is multiplied by a fixed value W. Therefore, the change of the gradient shows a change pattern of the pump flow rate (volume change amount per unit time).

FIG.11andFIG.12show calculation results of dSt/dθrobtained by differentiating the total area St(θr) inFIG.9andFIG.10, respectively, by θr. When the above is multiplied by each of the fixed values of an angular velocity ω and the thickness W of the cam ring, a calculation value obtained by differentiating the total volume by time t is obtained. Therefore, the calculation results inFIG.11andFIG.12indicate the fluctuation of the pump flow rate pattern on the suction side and the discharge side. Every calculation result of dSt/dθris a perfect fixed value in the entire range of the rotor rotation angle θr, and it can be understood that it is possible to cause the pump flow rate fluctuation to be zero on both the suction side and the discharge side in the first structure example of Embodiment 1.

In the rotary-vane-type hydraulic pump of the present invention, a first configuration condition for causing the pump flow rate fluctuation to be zero as inFIG.11andFIG.12is expressed by Expression (10). This means that an angle interval β of θrin which L(θr) becomes a fixed value is not smaller than the angle α between the rotor slits. In the first structure example of Embodiment 1, α=2π/5 (72°), β=θ1+θ5=θ3=2π/5 (72°) are satisfied as described above, and hence the first configuration condition of Expression (10) is satisfied.
[Expression 10]
β≥α  (10)

Similarly, a second configuration condition for causing the pump flow rate fluctuation to become zero in the present invention is expressed by Expression (11). This is a conditional expression in which the left-hand side is an angle obtained by subtracting the angle γ2of the second portion in which dL/dθris fixed from an angle γ that is θ2, θ4, or the like that is a profile interval in which the vanes perform the radial-direction movement in accordance with the rotation of the rotor, and the angle is n times of an angle in the brackets on the right-hand side obtained by subtracting the angle γ2of the second portion interval from an angle α′ between the rotor slits of two vanes sandwiching the second portion. Here, n represents an integer of 2 or more.
[Expression 11]
γ−γ2=n×(α−γ2)  (11)

In the first structure example of Embodiment 1, there are two vanes sandwiching each of the second portions on the suction side in the rotation position of the rotor12inFIG.7andFIG.13and the discharge side in the rotation position of the rotor12inFIG.16. However, α is greater than γ2as described above, and hence α′=α=2π/5 (72°) is satisfied. In addition, γ1=π/5) (36°) is satisfied and γ2=π/5 (36°) is satisfied. Therefore, γ=2γ1+γ2=3π/5 (108°) is satisfied. Expression (11) is satisfied at the time of n=2, and hence the second configuration condition is satisfied. The second configuration condition in Embodiment 1 is rewritten to Expression (12) by assigning n=2, α′=α, γ=2γ1+γ2to Expression (11).
[Expression 12]
γ1+γ2=α  (12)

Next, the reason it becomes possible to cause the pump flow rate fluctuation on the suction side to be zero by satisfying the first configuration condition and the second configuration condition and giving the motion of the vanes13by Expression (4) to Expression (9) in the first structure example of Embodiment 1 is described first with reference toFIG.13toFIG.18. When the number of the working chambers in the suction stroke is three as inFIG.13, a total volume Vst(θr) of each working chamber is expressed by Expression (13) with use of areas Ss1(θr), Ss2(θr), Ss3(θr) of each working chamber shown inFIG.13and the cam ring thickness W. Next, the right-hand side in Expression (13) is rewritten as in Expression (14) with use of Ss0(θr) inFIG.14and Ssv1(θr), Ssv2(θr), Ssv3(θr), Ssv4(θr) inFIG.15.
[Expression 13]
Vst(θr)=W×(Ss1(θr)+Ss2(θr)+Ss3(θr))  ((13)
[Expression 14]
Vst(θr)=W×(Ss0(θr)−Ssv1(θr)−Ssv2(θr)−Ssv3(θr)−Ssv4(θr))  (14)

Next, a pump flow rate Qs(t) on the suction side is first expressed by Expression (15) as a time change rate of Vst(θr). Then, the relationship of Expression (16) derived from θr=ωt by setting the rotation speed of the rotor to be the fixed value ω (rad/s) is assigned, and the pump flow rate Qs(t) is expressed by Expression (17) in the end.

[Expression⁢15]Qs(t)=W·{dSs⁢0dt-dSsv⁢1dt-dSsv⁢2dt-dSsv⁢3dt-dSsv⁢4st}(15)[Expression⁢16]dt=1ω⁢d⁢θr(16)[Expression⁢17]Qs(t)=W·ω·{dSs⁢0dt-dSsv⁢1dt-dSsv⁢2dt-dSsv⁢3dt-dSsv⁢4st}(17)

As described above, in the first structure example of Embodiment 1, the first configuration condition of β≤α of Expression (10) is satisfied. Therefore, the front vane forming the area Ss0(θr) inFIG.14is always in the state of jutting out from the slits the most in Expression (2), and the rear vane is always in the state of being pulled into the slits the most in Expression (1) or Expression (3) and remaining still in the slits. Therefore, lengths Rmaxand Rminof line segments connecting the center of the rotor12and each of two contact points between those vanes and the cam-ring inner circumferential surface14ato each other become fixed values, and Expression (19) is derived after the relational expression of Expression (18) is derived first where the rotor outer circumference radius is represented by Rr. It can be understood that a first term on the right-hand side in the curly brackets in Expression (17) is a fixed value in accordance with Expression (19) in the end. When the vane distal end is a circular arc having the radius Rvand the center P0is offset from the center of the rotor12to the opposite rotation side in a direction orthogonal to the direction of the rotor slit12aby Ofas in the first structure example, Rmaxand Rminare fixed values calculated by Expression (20) and Expression (21), respectively.

[Expression⁢18]dSs⁢0=Rmax22⁢d⁢θr-Rr22⁢d⁢θr-(Rmin22⁢d⁢θr-Rr22⁢d⁢θr)(18)[Expression⁢19]dSs⁢0d⁢θr=Rmax2-Rmin22(19)[Expression⁢20]Rmax=Lmax2+Of2+Rv(20)[Expression⁢21]Rmin=Lmin2+Of2+Rv(21)

In the first structure example, the first configuration condition of β≤α of Expression (10) is satisfied and a front vane and a rear vane forming Ss0(θr) are both remaining still in the slits, and hence the areas of those vane distal end portions do not change in accordance with θr. From the above, regarding a second term and a fifth term within the curly brackets on the right-hand side in Expression (17), Expression (22) is satisfied, and both become fixed values of zero.

[Expression⁢22]-dSsv⁢1d⁢θr=-dSsv⁢4d⁢θr=0(22)

Here, Expression (4) to Expression (9) are rewritten as below with use of the rotation angle θ of the rotor based on starting ends of the second interval and the fourth interval. First, in the second interval of the first structure example, the relationship of Expression (23) and the relationship of Expression (12) are assigned to Expression (4) to Expression (6), and Expression (24) is obtained in the first portion, Expression (25) is obtained in the second portion, and Expression (26) is obtained in the third portion. Similarly, in the fourth interval of the first structure example, the relationship of Expression (27) and the relationship of Expression (12) are assigned to Expression (7) to Expression (9), and Expression (28) is obtained in the first portion, Expression (29) is obtained in the second portion, and Expression (30) is obtained in the third portion.

[Expression⁢23]θr-θ1=θ(23)[Expression⁢24]L⁡(θ)=Lmax-Lmin2⁢α·θ-Lmax-Lmin2⁢α·γ1π·sin⁡(2⁢π⁢θ2⁢γ1)+Lmin(24)in the first portion 0≤θ<γ1in the second interval

[Expression⁢25]L⁡(θ)=Lmax-Lmin2⁢α·θ-Lmax-Lmin2⁢α·γ1+Lmin(25)in the second portion γ1≤θ<γ1+γ2in the second interval

[Expression⁢26]L⁡(θ)=Lmax-Lmin2⁢α·θ-Lmax-Lmin2⁢α·γ1π·sin⁡(2⁢π⁢θ-α+γ12⁢γ1)+Lmax-Lmin2⁢α·(α-γ1)+Lmin(26)in the third portion γ1+γ2≤θ<2γ1+γ2in the second interval

[Expression⁢27]θr-θ1-θ2-θ3=θ(27)[Expression⁢28]L⁡(θ)=-Lmax-Lmin2⁢α·θ+Lmax-Lmin2⁢α·γ1π·sin⁡(2⁢π⁢θ2⁢γ1)+Lmax(28)in the first portion 0≤θ<γ1in the fourth interval

[Expression⁢29]L⁡(θ)=-Lmax-Lmin2⁢α·θ+Lmax-Lmin2⁢α·γ1+Lmax(29)in the second portion γ1≤θ<γ1+γ2in the fourth interval

[Equation⁢30]L⁡(θ)=-Lmax-Lmin2⁢α·θ+Lmax-Lmin2⁢α·γ1π·sin⁡(2⁢π⁢θ-α+γ12⁢γ1)-Lmax-Lmin2⁢α·(α-γ1)+Lmax(30)in the third portion γ1+γ2≤θ<2γ1+γ2in the fourth interval

Two vanes having distal end areas of Sav2(θr) and Ssv3(θr) are in the first portion and the third portion, and hence a third term and a fourth term within the curly brackets on the right-hand side in Expression (17) are respectively calculated by Expression (31) and Expression (32) by giving the positions L(θ) in the slits of the vanes by Expression (24) and Expression (26), performing differentiation by θ, and performing multiplication by the vane thickness T, and the total thereof becomes a fixed value of Expression (33).

[Expression⁢31]-dSsv⁢2d⁢θr=-T·dL⁡(θr)d⁢θr=-T·dL⁡(θ)d⁢θ=-T·Lmax-Lmin2⁢α+T·Lmax-Lmin2⁢α·cos⁡(2⁢π⁢θ2⁢γ1)(31)[Expression⁢32]-dSsv⁢3d⁢θr=-T·dL⁡(θr+α)d⁢θr=-T·dL⁡(θ+α)d⁢θ=-T·Lmax-Lmin2⁢α+T··cos⁡(2⁢π⁢θ+α-α+γ12⁢γ1)=-T·Lmax-Lmin2⁢α+T·Lmax-Lmin2⁢α·cos⁡(2⁢π⁢θ2⁢γ1+π)(32)[Expression⁢33]-dSsv⁢2d⁢θr-dSsv⁢3d⁢θr=-T·Lmax-Lminα(33)

It has been able to be proved that the suction-side pump flow rate Qs(t) becomes a fixed value on the right-hand side in Expression (34) when Expression (19), Expression (22), and Expression (33) are assigned to Expression (17) when the number of the working chambers in the suction stroke is three in the first structure example of Embodiment 1.

[Expression⁢34]Qs(t)=W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(34)

When the number of the suction working chambers is two as inFIG.16, a total volume Vst(θr) of each working chamber volume is expressed by Expression (35) with use of areas Ss1(θr), Ss2(θr) of each working chamber shown inFIG.16and the cam ring thickness W. The right-hand side in Expression (35) is rewritten as in Expression (36) with use of Ss0(θr) inFIG.17and Ssv1(θr), Ssv2(θr), Ssv3(θr) inFIG.18.
[Expression 35]
Vst(θr)=W×(Ss1(θr)+Ss2(θr))  (35)
[Expression 36]
Vst(θr)=W×(Ss0(θr)−Ssv1(θr)−Ssv2(θr)−Ssv3(θr)  (36)

The pump flow rate Qs (t) on the suction side in this case is expressed by Expression (37) as the time change of Vst(θr) first, the relationship of Expression (16) is assigned, and the pump flow rate Qs(t) is expressed by Expression (38) in the end.

[Expression⁢37]Qs(t)=W·{dSs⁢0dt-dSsv⁢1dt-dSsv⁢2dt-dSsv⁢3dt}(37)[Expression⁢38]Qs(t)=W·ω·{dSs⁢0dt-dSsv⁢1dt-dSsv⁢2dt-dSsv⁢3dt}(38)

By satisfying an effect element of β≤α of Expression (10) in the first structure example of Embodiment 1, a first term in the curly brackets on the right-hand side in Expression (38) is given by a fixed value of Expression (19), and a second term and a fourth term are given by fixed values of Expression (39) even when the number of the suction working chambers is two as with a case where the number of the suction working chambers is three.

[Expression⁢39]-dSsv⁢1d⁢θr=-dSsv⁢3d⁢θr=0(39)

As above, it becomes possible to establish Expression (19) and Expression (22) or Expression (39) and cause all of the first term, the second term, and the fifth term in the curly brackets on the right-hand side in Expression (17) or the first term, the second term, and the fourth term in the curly brackets on the right-hand side in Expression (38) to be fixed values that do not change with time by simply satisfying the configuration condition of β≤α in Expression (10) in the first structure example of Embodiment 1. As a result, it becomes possible to greatly contribute to the reduction of the time change of the pump flow rate Qs(t) on the suction port side.

The vanes having the distal end area of Ssv2(θr) are in the second portion, and hence a third term in the curly brackets on the right-hand side in Expression (38) becomes a fixed value of Expression (40) by giving the position L(θ) in the slits of those vanes by Expression (25), performing differentiation by θ, and performing multiplication by the vane thickness T.

[Expression⁢40]-dSvs⁢2(θr)d⁢θr=-T·dL⁡(θr)d⁢θr=-T·dL⁡(θ)d⁢θ=-T·Lmax-Lminα(40)

It has been able to be proved that the suction-side pump flow rate Qs(t) becomes a fixed value on the right-hand side in Expression (41) when Expression (19), Expression (39), and Expression (40) are assigned to Expression (38) when the number of the working chambers in the suction stroke is two in the first structure example.

[Expression⁢41]Qs(t)=W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(41)

Expression (41) is equal to Expression (34) and is a perfect fixed value. Therefore, it has been proved that the suction-side pump flow rate Qs(t) always becomes fixed and the fluctuation becomes zero regardless of the rotor rotation angle θrin the first structure example. The calculation result of dSt/dθrinFIG.11is equivalent to the inside of the brackets on the right-hand side in Expression (34) or the right-hand side in Expression (41). Therefore, it has also been able to be verified that the fluctuation pattern of the suction-side pump flow rate inFIG.11calculated by obtaining the total area St(θr) of the suction working chambers as a function of θrand obtaining the gradient with respect to θrbecomes a completely fixed value at the same time.

On the suction side in the first structure example, the fluctuation reduction effect due to the first configuration condition of Expression (10) being satisfied is great because the right-hand sides in Expression (34) and Expression (41) become the same fixed values, but it becomes possible to further reduce the time change of the pump flow rate Qs(t) to be completely zero by further satisfying the second configuration condition in Expression (12) and a third configuration condition that defines the profile of the cam-ring inner circumferential surface14ain the second interval by Expression (24) to Expression (26).

A discharge-side pump flow rate Qd(t) when the number of the discharge working chambers is three in the first structure example of Embodiment 1 is calculated by a similar procedure by performing replacement and the like below in each of Expressions of (13), (14), (15), (17), (18), (19), (22), (31), (32), (33), (34) in the calculation procedure of the suction-side pump flow rate Qs(t) described above. In other words, Vst(θr) is replaced with a total volume Vdt(θr) of each discharge-side working chamber volume, Ss1(θr), Ss2(θr), Ss3(θr) are replaced with Sd1(θr), Sd2(θr), Sd3(θr) shown inFIG.16, Ss0(θr), Ssv1(θr), Ssv2(θr), Ssv3(θr), Ssv4(θr) are replaced with Sd0(θr), Sdv1(θr), Sdv2(θr), Sdv3(θr), Sdv4(θr) shown inFIG.17andFIG.18, Qs(t) is replaced with Qd(t), Rmaxand Rminare replaced with each other, L(θ) in Expression (31) and Expression (32) is given by functional forms of Expression (28) and Expression (30), respectively, and Lmaxand Lminare replaced with each other. As a result, the discharge-side pump flow rate Qd(t) when the number of the discharge working chambers is three is calculated by Expression (42).

[Expression⁢42]Qd(t)=-W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(42)

The discharge-side pump flow rate Qd(t) when the number of the discharge working chambers is two in the first structure example of Embodiment 1 is calculated by a similar procedure by performing replacement and the like below in each of Expressions of (35), (36), (37), (38), (18), (19), (39), (40), (41) in the calculation procedure of the suction-side pump flow rate Qs(t) described above. In other words, Vst(θr) is replaced with each the total volume Vat (θr) of the discharge-side working chamber volume, Ss1(θr), Ss2(θr) are replaced with Sd1(θr), Sd2(θr) shown inFIG.13, Ss0(θr), Ssv1(θr), Ssv2(θr), Ssv3(θr) are replaced with Sd0(θr), Sdv1(θr), Sdv2(θr), Sdv3(θr) shown inFIG.14andFIG.15, Qs(t) is replaced with Qd(t), Rmaxand Rminare replaced with each other, L(θ) in Expression (40) is given by a functional form of Expression (29), and Lmaxand Lminare replaced with each other. As a result, the discharge-side pump flow rate Qd(t) when the number of the discharge working chambers is two is calculated by Expression (43). Expression (43) is equal to Expression (42) and is a perfect fixed value. Therefore, it has been proved that the discharge-side pump flow rate Qd(t) also always becomes fixed and the fluctuation becomes zero regardless of the rotor rotation angle θrin the first structure example. The calculation result of dSt/dθrinFIG.12is equivalent to the inside of the brackets on the right-hand side in Expression (42) or the right-hand side in Expression (43). Therefore, it has also been able to be verified that the fluctuation pattern of the discharge-side pump flow rate inFIG.12calculated by obtaining the total area St(θr) of the discharge working chambers as a function of θrand obtaining the gradient with respect to θrbecomes a completely fixed value at the same time.

[Expression⁢43]Qd(t)=-W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(43)

The fluctuation reduction effect due to the first configuration condition of Expression (10) is also great on the discharge side because the right-hand sides in Expression (42) and Expression (43) are caused to become the same fixed values, but it becomes possible to further reduce the time change of the pump flow rate Qd(t) to be completely zero by further satisfying the second configuration condition of Expression (12) and the third configuration condition that defines the profile of the cam-ring inner circumferential surface14ain the fourth interval by Expression (28) to Expression (30).

To define the profile of the cam-ring inner circumferential surface14aby Expression (24) to Expression (26) and Expression (28) to Expression (30) respectively in the second interval and the fourth interval means to give the vane position L(θr) at the rotor rotation angle θrcorresponding to θ in those expressions by the functional forms of Expression (4) to Expression (9), in other words, “to form the profile of the cam-ring inner circumferential surface by the first portion, the second portion, and the third portion smoothly connected in order in the interval of the rotor rotation angle θrin which the rotor slit direction displacement L(θr) of the fixed point on the vane with respect to the rotor center changes, and give L(θr) as a linear function of θrin the second portion and a sum of a linear function of θrand a periodic function of which period is 2γ1in the first portion and the third portion, cause a differential value of the function L(θr) by θrto become zero at a starting end of the first portion and a terminal end of the third portion, be a same value at a terminal end of the first portion and a starting end of the third portion, and be a fixed value equal to the same value in the second portion when the change amount of θris equally γ1in the first portion and the third portion and the change amount of θrof the second portion is γ2”, and this is an expression by a sentence of the third configuration condition of the present invention.

As above, in the first structure example of Embodiment 1, it is proved that it becomes possible to theoretically cause the fluctuation of the pump flow rate to be zero by satisfying the first configuration condition of Expression (10) in the present invention, also satisfying the second configuration condition of Expression (11) by satisfying Expression (12), giving the vane position L(θr) by the functional forms of Expression (4) to Expression (9), and also satisfying the third configuration condition of defining the cam-ring inner circumferential surface14a. The first structure example is particularly characterized in that the above can be realized by a configuration in which the number of vanes is small (Nv=5). The pump flow rate Qd(t) on the discharge side in Expression (42) and Expression (43) has the same absolute value and has different signs from the pump flow rate Qs(t) on the suction side in Expression (34) and Expression (41), but this is due to the difference between suction and discharge. When Qs(t) and Qd(t) are divided by W·ω, dSt/dθrinFIG.11andFIG.12is obtained, but values calculated with use of various dimensions in the first structure example are 126.08 and −126.08 on the suction side and the discharge side, respectively, and exactly match with the fixed values obtained by the calculation ofFIG.11andFIG.12.

The rotary-vane-type hydraulic pump that is the second structure example of Embodiment 1 of the present invention in which each working chamber performs a plurality of times of suction and discharge during one rotor rotation is described with reference toFIG.19toFIG.22.FIG.19is a diagram showing how vanes move in accordance with the rotor rotation angle in order to define a cam ring profile in the second structure example.FIG.20is a front view showing the cam ring profile, a rotor, each vane, a suction port, and a discharge port of the second structure example.FIG.21is a diagram showing a change of the volume of each working chamber that communicates with one suction port in the second structure example and the total volume thereof as functions of the rotor rotation angle.FIG.22is a diagram showing a pump flow-rate fluctuation pattern from one suction port of the second structure example of Embodiment 1 that is the differential value of the total volume inFIG.21by the rotor rotation angle.

The change amount of θrin each of the intervals from the first interval to the fifth interval in the second structure example inFIG.19is θ1=π/10 (18°), θ2=3π/10 (54°), θ3=π/5 (36°), θ4=3π/10 (54°), and θ5=π/10) (18°, and γ1=π/10 (18°) and γ2=π/10 (18°) are also satisfied in each portion. Therefore, every change amount of θrin each portion and each interval in the second structure example is half of each interval in the first structure example shown inFIG.8. As a result, the suction and discharge are performed two times during one rotor rotation. As shown inFIG.20, the number of vanes23Nv=10 is satisfied, and hence α=2π/10=π/5 (36°) is satisfied, which is also half of that of the first structure example. The dimension of each portion is Lmin=21 mm, Lmax=24 mm, the rotor diameter Dr=45 mm, the vane distal-end circular-arc radius Rv=2.5 mm, the distal-end circular-arc-center offset Of=0 mm, and the vane thickness T=1.6 mm.

The first configuration condition of Expression (10) and the second configuration condition of Expression (12) derived from Expression (11) are also satisfied by the setting of the angle of each portion in the second structure example of Embodiment 1. As with the first structure example, L(θr) of each portion interval inFIG.19is given by the functional forms of Expression (4) to Expression (9), and hence the third configuration condition of the present invention is also satisfied. Expression (4′) to Expression (9′) inFIG.19are expressions in which θrin Expression (4) to Expression (9) is replaced with θr-π, but the functional forms are the same.

In the second structure example of Embodiment 1, there are two suction ports and two discharge ports as shown inFIG.20. However, a calculation result relating to the pump flow rate fluctuation passing through one of the suction ports is shown inFIG.21andFIG.22here. In the second structure example, as shown inFIG.20, there are ten working chambers of which phases are shifted from each other by the angle α=π/5 (36°) between the adjacent rotor slits, the working chambers each communicate with the suction ports one after another in accordance with the rotation of the rotor22, and the number of the working chambers that communicate with the suction ports at a certain θrinFIG.21is three or two depending on the time as with the first structure example. This is due to all of the angle specifications described above being reduced to half and the ratio between each angle not changing from the first structure example.

As withFIG.9, when the number of the working chambers that communicate with one suction port changes, the size of the total area thereof changes in a stepwise manner also inFIG.21, but the change is made with a fixed gradient while the number of the communicating working chambers does not change. As a result, it can be confirmed that the differential value of the total area by the rotor rotation angle shown inFIG.22becomes a fixed value in the entire region of θr, and the flow rate fluctuation becomes zero as a result of the pump flow rate pattern passing through one suction port being fixed.

As described above, all of the first configuration condition, the second configuration condition, and the third configuration condition of the present invention are also satisfied in the second structure example, and hence the verification result that directly proves that the pump flow rate fluctuation becomes zero without obtaining the working chamber area in the first structure example can be directly applied. In other words, it is proved that a feature in which the pump flow rate passing through one suction port theoretically becomes the fixed value on the right-hand side in Expression (34) and Expression (41) in the first structure example is also established in the second structure example and that the pump flow rate pattern passing through the suction port inFIG.22becomes fixed. At the same time, the verification result in the first structure example can also be directly applied to the discharge side, and hence it can also be proved that the pump flow rate passing through one discharge port in the second structure example theoretically becomes the fixed value on the right-hand side in Expression (42) and Expression (43).

There are two suction ports and two discharge ports in the second structure example of Embodiment 1. Therefore, the pump flow rate Qs(t) on the suction side is twice as much as the right-hand side in Expression (34) and Expression (41) and is expressed by Expression (44), and the pump flow rate Qd(t) on the discharge side is also twice as much as the right-hand side in Expression (42) and Expression (43) and is expressed by Expression (45). Both are fixed values, and the flow rate fluctuation is zero.

[Expression⁢44]Qs(t)=2⁢W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(44)[Expression⁢45]Qd(t)=-2⁢W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(45)

As above, it is proved that the pump flow rate also becomes the fixed values of Expression (44) and Expression (45) and the fluctuation thereof also theoretically becomes zero in the second structure example of Embodiment 1. The value obtained by dividing Qs(t) on the suction side of Expression (44) by 2W·ω becomes dSt/dθrinFIG.22. The value calculated with use of various dimensions of the second structure example is 67.36 and exactly matches with the fixed calculation value inFIG.22. The second structure example is particularly characterized in that the bearing load and the vibration become smaller. This is because the part configuration is disposed to be symmetrical about a point of the rotor center, and the force by the surface pressure and the inertial force that act on parts having the same shape and opposite from each other by 180° offset each other and disappear.

A rotary-vane-type hydraulic pump that is the third structure example of Embodiment 1 of the present invention is described with reference toFIG.23andFIG.24.FIG.23is a diagram showing how the vanes move in accordance with the rotor rotation angle in order to define a cam ring profile of the rotary-vane-type hydraulic pump that is the third structure example of Embodiment 1 of the present invention in which a circular arc portion of the cam ring profile is extended.FIG.24is a front view showing the cam ring profile, a rotor, each vane, a suction port, and a discharge port of the third structure example.

In the third structure example of Embodiment 1, the change amount of θrin the first interval to the fifth interval inFIG.23is θ1=π/5 (36°), θ2=53π/90 (106°), θ3=19π/45 (76°), θ4=53π/90 (106°), and θ5=π/5 (36°), the change amount of θrin each portion is γ1=17π/90 (34°) and γ2=19π/90 (38°), and L(θr) in each portion is given by the functional forms of Expression (4) to Expression (9). Regarding the vanes, the number Nv=5 and α=2π/5 (72°) are satisfied. Each portion dimension is Lmin=21 mm, Lmax=26 mm, the rotor diameter Dr=46 mm, the vane distal-end circular-arc radius Rv=3 mm, the distal-end circular-arc-center offset Of=2 mm, and the vane thickness T=1.6 mm.

Therefore, the first configuration condition of Expression (10) and the second configuration condition of Expression (12) derived from Expression (11) are also satisfied by the setting of the angle of each portion described above in the third structure example. As with the first structure example, L(θr) in each portion inFIG.23is given by the functional forms of Expression (4) to Expression (9), and hence the third configuration condition of the present invention is also satisfied. Therefore, the verification result performed in the first structure example can also be directly applied in the third structure example. In other words, it can also be proved that the pump flow rate Qs(t) on the suction side is theoretically given by Expression (46) equal to Expression (34) and Expression (41), and the discharge-side pump flow rate Qd(t) is theoretically given by Expression (47) equal to Expression (42) and Expression (43) in the third structure example. Both are fixed values, and the flow rate fluctuation is zero.

[Expression⁢46]Qs(t)=W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(46)[Expression⁢47]Qd(t)=-W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(47)

As above, it is proved that the fluctuation of the pump flow rate also theoretically becomes zero in the third structure example of Embodiment 1. The third structure example is particularly characterized in that the occurrence of a pulse-like pressure pulsation and leakage between the ports when the ports that communicate with the working chambers are switched is easily suppressed. The is because θ3(76°) of the third interval is caused to be greater than α (72°), the interval between each port inFIG.24is caused to be wider than the width of the working chamber, the pulse pulsation is alleviated by formation of a notch portion, and airtightness between each port by vane end surfaces is improved.

Embodiment 2

A rotary-vane-type hydraulic pump that is a structure example of Embodiment 2 of the present invention is described with reference toFIG.25toFIG.29.FIG.25is a diagram showing how vanes move in accordance with the rotor rotation angle in order to define a cam ring profile in the structure example of Embodiment 2.FIG.26is a front view showing the cam ring profile, a rotor, each vane, a suction port, and a discharge port of this structure example.FIG.27is a diagram showing a change of a front area of each working chamber in a suction stroke and a total area thereof in the structure example of Embodiment 2 inFIG.26as functions of a rotor rotation angle.FIG.28is a diagram showing a pump flow-rate fluctuation pattern on the suction side of the structure example of Embodiment 2 that is a differential value of the total area inFIG.27by the rotor rotation angle.FIG.29is a diagram for describing the reason the flow rate fluctuation becomes zero by the general structure of Embodiment 2.

The change amount of θrin each of the intervals from the first interval to the fifth interval inFIG.25in the structure example of Embodiment 2 is θ1=π/8) (22.5°, θ2=3π/4 (135°), θ3=π/4 (45°), θ4=π/4 (135°), and θ5=π/8 (22.5°), the change amount of θrin each portion is γ1=γ3=π/4 (45°) and γ2=π/4 (45°), and L(θr) in each portion is given by the functional forms of Expression (4) to Expression (9). Regarding the vanes, the number Nv=8 and α=2π/8=π/4 (45°) are satisfied. Each portion dimension is Lmin=21 mm, Lmax=26 mm, the rotor diameter Dr=46 mm, the vane distal-end circular-arc radius Rv=3 mm, the distal-end circular-arc-center offset Of=0 mm, and the vane thickness T=1.6 mm.

In the structure example of Embodiment 2, α=π/4) (45° is satisfied for both cases in which β is θ1+θ5=π/4) (45° and θ3=π/4 (45°), and hence Expression (10) that is the first configuration condition of the invention is satisfied. Here, γ=2γ1+γ2and γ1=γ2=a are satisfied on the left-hand side in Expression (11), and hence the entire left-hand side becomes 2α. In addition, α′=2α and γ2-α are satisfied on the right-hand side, and hence the entire right-hand side becomes nα, and Expression (11) is established by n=2 (integer of 2 or more). Therefore, this structure example also satisfies Expression (11) that is the second configuration condition of the invention. The third configuration condition of the invention is also satisfied by giving L(θr) in each portion by the functional forms of Expression (4) to Expression (9).

As the general structure of Embodiment 2, the common change amount γ1of θrin the first portion and the third portion and the change amount γ2of θrin the second portion interval are given by Expression (48) and Expression (49) with use of the angle α between the vane slits and n1and n2that are freely-selected natural numbers. When those expressions are used, the left-hand side in Expression (11) becomes 2n1α also in consideration of γ=2γ1+γ2and the right-hand side becomes n·α also in consideration of α′=(n2+1)α. Here, n1on the left-hand side is a freely-selected natural number, and hence n on the right-hand side becomes an integer of 2 or more, and Expression (11) is established. In other words, the second configuration condition of the present invention is rewritten to Expression (48) and Expression (49) in Embodiment 2. Here, n1and n2are freely-selected natural numbers.
[Expression 48]
γ1=n1·α  (48)
[Expression 49]
γ2=n2·α  (49)

In the structure example of Embodiment 2, the number of vanes is eight, and hence there are always eight working chambers of which phases are shifted from each other by α=2π/8 (45°) as shown inFIG.26.FIG.27shows the change of the front area S of each working chamber when the above is in the suction stroke as a function of the rotor rotation angle θr. The number of the suction working chambers each in the position of a certain θrin the horizontal axis is always four, and the calculation result of the total area St(θr) of those front areas S(θr): S1 to S4 is also shown in the same drawing. The differential value dSt/dθrof the total area St(θr) by the rotor rotation angle θrinFIG.27is shown inFIG.28as the pump flow-rate fluctuation pattern on the suction side, but it can be understood that the differential value dSt/dθris a fixed value in the entire range of the rotor rotation angle θr, and the fluctuation of the pump flow rate Qs(t) on the suction side can also be caused to be zero in the structure example of Embodiment 2. It is understood that, when the pump flow-rate fluctuation pattern on the discharge side is calculated by a similar procedure, the pump flow-rate fluctuation pattern also becomes a fixed value and the fluctuation of the pump flow rate Qd(t) on the discharge side can also be caused to be zero as with the first structure example of Embodiment 1.

The reason the fluctuation of the pump flow rate Qs(t) on the suction side in the structure example of Embodiment 2 becomes zero is described below with use of expressions. In this structure example, the number of the working chambers in the suction stroke is always four and the number of the vanes forming the working chambers is five as inFIG.26, and hence Expression (17) of Qs(t) when the number of the working chambers is three and the number of the vanes forming the working chambers is four as inFIG.13is rewritten to Expression (50). Here, Ssv5is an area of a distal end portion of the vane that is added by one number. The structure example of Embodiment 2 also satisfies Expression (10) that is the first configuration condition of the invention.

Therefore, as with Embodiment 1, a first term in the curly brackets in Expression (50) is a fixed value in accordance with Expression (19) and a second term and the final term in the curly brackets become fixed values of zero in Expression (51).

[Expression⁢50]Qs(t)=W·ω·{dSs⁢0d⁢θr-dSs⁢1d⁢θr-dSs⁢2d⁢θr-dSs⁢3d⁢θr-dSs⁢4d⁢θr-dSs⁢5d⁢θr}(50)[Expression⁢51]-dSsv⁢1d⁢θr=-dSsv⁢5d⁢θr=0(51)

Here, Expression (4) to Expression (9) are rewritten to Expression (52) to Expression (54) with use of the rotor rotation angle θ of the starting end reference of the second interval in accordance with Expression (23). The functional forms of the vane position L of a third term to a fifth term in the curly brackets in Expression (50) are given by each of Expression (52) to Expression (54) in accordance with the rotor rotation angle θ.

[Expression⁢52]L⁡(θ)=Lmax-Lmin2⁢(γ1+γ2)·θ-Lmax-Lmin2⁢(γ1+γ2)·γ1π·sin⁡(2⁢π⁢θ2⁢γ1)+Lmin(52)in the first portion 0≤θ<γ1in the second interval

[Expression⁢53]L⁡(θ)=Lmax-Lminγ1+γ2·θ-Lmax-Lmin2⁢(γ1+γ2)·γ1·Lmin(53)in the second portion γ1≤θ<γ1+γ2in the second interval

[Expression⁢54]L⁡(θ)=Lmax-Lmin2⁢(γ1+γ2)·θ-Lmax-Lmin2⁢(γ1+γ2)·γ1π·sin⁡(2⁢π⁢θ-γ22⁢γ1)+Lmax-Lmin2⁢(γ1+γ2)·γ2+Lmin(54)in the third portion γ1+γ2≤θ<2γ1+γ2in the second interval

Expressions of the third term and the fifth term in the curly brackets on the right-hand side in Expression (50) are calculated by Expression (55) and Expression (56) by giving the functional forms of L(θ) that are the vane positions thereof by each of Expression (52) and Expression (54), performing differentiation by θ, and performing multiplication by the vane thickness T. At the time of derivation of Expression (56), the relationships of α′=2α and γ1-γ2-α in the structure example of Embodiment 2 are also used. The total thereof is a fixed value on the rightmost-hand side in Expression (57).

[Expression⁢55]-dSsv⁢2d⁢θr=-T·dL⁡(θ)d⁢θ=-T·Lmax-Lmin2⁢(γ1+γ2)+T·Lmax-Lmin2⁢(γ1+γ2)·cos⁡(2⁢π⁢θ2⁢γ1)(55)[Expression⁢53]-dSsv⁢4d⁢θr=-T·dL⁡(θ+α′)d⁢θ=-T·Lmax-Lmin2⁢(γ1+γ2)+T·Lmax-Lmin2⁢(γ1+γ2)·cos⁡(2⁢π⁢θ+2⁢α-γ22⁢γ1)=-T·Lmax-Lmin2⁢(γ1+γ2)+T·Lmax-Lmin2⁢(γ1+γ2)·cos⁡(2⁢π⁢θ2⁢γ1+π)(53)[Expression⁢57]-dSsv⁢2d⁢θr-dSsv⁢4d⁢θr=-T·Lmax-Lminγ1+γ2=-T·Lmax-Lmin2⁢α(57)

A fourth term in the curly brackets on the right-hand side in Expression (50) becomes a fixed value on the rightmost-hand side in Expression (58) by giving the functional form of L(θ+α) that is the vane position thereof by Expression (53), performing differentiation by θ, performing multiplication by the vane thickness T, and also using a relationship of γ1=γ2=α in the structure example of Embodiment 2.

[Expression⁢58]-dSsv⁢3d⁢θ=-T·dL⁡(θ+α)d⁢θ=-T·Lmax-Lminγ1+γ2=-T·Lmax-Lmin2⁢α(58)

Expression (19), Expression (51), Expression (57), and Expression (58) are assigned to Expression (50), and the pump flow rate Qs(t) on the suction side in the structure example of Embodiment 2 is obtained as a fixed value on the right-hand side in Expression (59) equal to Expression (34) and Expression (41) in the first structure example of Embodiment 1. As a result, it is proved that the fluctuation of the suction-side pump flow rate also theoretically becomes zero in the structure example of Embodiment 2. At the same time, it has also been able to be verified that the total volume Stof the suction working chamber is obtained as the function of θr, and the fluctuation pattern dSt/dθrof the pump flow rate Qs(t) on the suction side inFIG.28calculated from the gradient with respect to θralways becomes a fixed value. The value obtained by dividing Qs(t) on the suction side of Expression (59) by W·ω becomes dSt/dθrinFIG.28. The value calculated with use of various dimensions of the structure example of Embodiment 2 is 122.31 and exactly matches with the fixed calculation value inFIG.28. The discharge-side pump flow rate Qd(t) in the structure example of Embodiment 2 is similarly obtained as a fixed value on the right-hand side in Expression (60).

[Expression⁢59]Qs(t)=W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(59)[Expression⁢60]Qd(t)=-W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(60)

In Embodiment 2, the second configuration condition of a general structure including not only the structure examples shown inFIG.25andFIG.26but also other structure examples is Expression (48) and Expression (49). In other words, both of γ1common to the first portion and the third portion and γ2of the second portion in intervals in which the vanes perform an advance and retreat movement are multiples of the angle α between the vane slits. At this time, for example, the number of the vanes in the second interval on the suction side is 2n1+n2, and hence Expression (61) is obtained when Expression (50) is rewritten to a general form using n1and n2. The general structure of Embodiment 2 also satisfies the first configuration condition of Expression (10), and hence a first term in the curly brackets on the right-hand side becomes Expression (19), and a second term and the final term become Expression (62).

[Expression⁢61]Qs(t)=W·ω·{dSs⁢0d⁢θr-dSsv⁢1d⁢θr-∑m=12⁢n1+n2dSsv⁡(m+1)d⁢θr-dSsv⁡(2⁢n1+n2+2)d⁢θr}(61)[Expression⁢62]-dSsv⁢1d⁢θr=-dSsv⁡(2⁢n1+n2+2)d⁢θr=0(62)

A sum total portion of a third term on the right-hand side in the curly brackets in Expression (61) is expressed by Expression (63) when being separated into the sum total of the vanes in each portion. Each term on the right-hand side in Expression (63) corresponds to the first portion, the second portion, and the third portion, and hence is calculated by Expression (64) to Expression (66) by giving the functional form of L(θ) that is each of the vane positions by Expression (52) to Expression (54), performing differentiation by θ, and performing multiplication by the vane thickness T. The relationship of Expression (48) is used at the time of derivation of Expression (64), and the relationship of Expression (48) and Expression (49) is used at the time of derivation of Expression (66).

[Expression⁢63]-∑m=12⁢n1+n2dSsv⁡(m+1)d⁢θr=-∑m=1n1dSsv⁡(m+1)d⁢θr-∑m=n1+1n1+n2dSsv⁡(m+1)s⁢θr-∑m=n1+n2+12⁢n1+n2dSsv⁡(m+1)d⁢θr(63)[Expression⁢64]-∑m=1n1dSsv⁡(m+1)d⁢θr=-T⁢∑m=1n1dL⁡(θ+(m-1)⁢α)d⁢θ=-T·n1·Lmax-Lmin2⁢(γ1+γ2)+T·Lmax-Lmin2⁢(γ1+γ2)·∑m=1n2cos⁡(2⁢π⁢θ2⁢γ1+2⁢π2⁢n1⁢(m-1))(64)[Expression⁢65]-∑m=n1+1n1+n2dSsv⁡(m+1)d⁢θr=-T⁢∑m=n1+1n1+n2dL⁡(θ+(m-1)⁢α)d⁢θ=-T·n2·Lmax-Lminγ1+γ2(65)[Expression⁢66]-∑m=n1+n2+12⁢n1+n2dSsv⁡(m+1)d⁢θr=-T⁢∑m=n1+n2+12⁢n1+n2dL⁡(θ+(m-1)⁢α)d⁢θ=-T⁢∑m=n1+n2+12⁢n1+n2Lmax-Lmin2⁢(γ1+γ2)+T·Lmax-Lmin2⁢(γ1+γ2)·∑m=n1+n2+12⁢n1+n2cos⁡(π⁢θ-γ2+(m-1)⁢α)γ1)=-T·n1·Lmax-Lmin2⁢(γ1+γ2)+T·Lmax-Lmin2⁢(γ1+γ2)·∑m=n1+12⁢n1cos⁡(2⁢π⁢θ2⁢γ1+2⁢π2⁢n1⁢(m-1))(66)

Expression (64) to Expression (66) are assigned to Expression (63), and a sum total portion of a third term in the curly brackets on the right-hand side in Expression (61) is rewritten as in Expression (67) first. A sum total portion of a third term on the right-hand side in Expression (67) is a sum of an X coordinate of a number of 2n1mass points M1to M2n1that are the same in mass and are disposed at even intervals on a circle having a radius of 1 about a center of an origin O shown inFIG.29and becomes an X coordinate of the center of gravity thereof when being divided by 2n1. It is obvious that the center of gravity is in the origin byFIG.29, and hence Expression (68) is always established. A fixed value of Expression (69) is obtained when relational expressions of Expression (48) and Expression (49) are used.

[Expression⁢67]-∑m=12⁢n1+n2dSsv⁡(m+1)d⁢θr=-T·n1·Lmax-Lminγ1+γ2-T·n2·Lmax-Lminγ1+γ2+Τ·Lmax-Lmin2⁢(γ1+γ2)·∑m=12⁢n1cos⁡(2⁢π⁢θ2⁢γ1+2⁢π2⁢n1⁢(m-1))(67)[Expression⁢68]∑m=12⁢n1cos⁡(2⁢π⁢θ2⁢γ1+2⁢π2⁢n1⁢(m-1))=0(68)[Expression⁢69]-∑m=12⁢n1+n2dSsv⁡(m+1)d⁢θr=-T·(n1+n2)⁢(Lmax-Lmin)γ1+γ2=-T⁡(Lmax-Lmin)α(69)

The pump flow rate Qs(t) on the suction side in the general structure of Embodiment 2 becomes a fixed value given by Expression (70) by assigning Expression (19), Expression (62), and Expression (69) to Expression (61). The value obtained by dividing Qs(t) on the suction side of Expression (70) by W·ω becomes dSt/dθrinFIG.28. The value calculated with use of various dimensions of the structure example of Embodiment 2 is 122.31 and exactly matches with the fixed calculation value inFIG.28. The discharge-side pump flow rate Qd(t) in the general structure of Embodiment 2 is also obtained as a fixed value on the right-hand side in Expression (71) by a procedure similar to that of the suction side.

[Expression⁢70]Qs(t)=W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(70)[Expression⁢71]Qd(t)=-W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(71)

As a result of the above, it is also proved that the fluctuation of the pump flow rate theoretically becomes zero in the general structure of Embodiment 2 by satisfying the first configuration condition of Expression (10) in the present invention, also satisfying the second configuration condition of Expression of Expression (11) by satisfying Expression (48) and Expression (49), giving the vane position L(θr) by the functional forms of Expression (4) to Expression (9), and also satisfying the third configuration condition. The general structure of Embodiment 2 is particularly characterized in being advantageous in terms of speed-up because the inertial force can be reduced by increasing n1in Expression (48) and n2in Expression (49), expanding the radial-direction movement interval of the vanes, and causing the vanes to slowly advance and retreat.

Embodiment 3

A rotary-vane-type hydraulic pump that is Embodiment 3 of the present invention is described with reference toFIG.30toFIG.33.FIG.30is a diagram showing how vanes move in accordance with the rotor rotation angle in order to define a cam ring profile in the structure example of Embodiment 3.FIG.31is a front view showing the cam ring profile, a rotor, each vane, a suction port, and a discharge port of this structure example.FIG.32is a diagram showing a change of a front area of each working chamber in a suction stroke and a total area thereof in the structure example inFIG.31as functions of a rotor rotation angle.FIG.33is a diagram showing a pump flow-rate fluctuation pattern on the suction side of the structure example of Embodiment 3 that is a differential value of the total area inFIG.32by the rotor rotation angle.

In the structure example of Embodiment 3, the change amount of θrin each of the intervals from the first interval to the fifth interval inFIG.30is θ1=π/6 (30°), θ2=2π/3 (120°), θ3=π/3 (60°), θ4=12π/3 (120°), and θ5=π/6 (30°), γ1=π/3 (60°) and γ2=0° are satisfied in each portion, and the number of the vanes Nv=6 and α=2π/6=π/3) (60° are satisfied. The functional form of L(θr) in each interval inFIG.30is given by each expression where γ2=0° is satisfied in Expression (1) to Expression (9) in Embodiment 1. Unlike the other embodiments, it is characterized in that γ2=0° is satisfied and there are no intervals in which dL/dθrbecomes fixed. Each portion dimension is Lmin=21 mm, Lmax=26 mm, the rotor diameter Dr=46 mm, the vane distal-end circular-arc radius Rv=3 mm, the distal-end circular-arc-center offset Of=2 mm, and the vane thickness T=1.6 mm.

In the structure example of Embodiment 3, α=π/3) (60° and β=θ1+θ5=θ3=π/3 (60°) are satisfied as described above, and hence the first configuration condition of Expression (10) is satisfied as with Embodiment 1. In Embodiment 3, γ2=0° and α′=α are satisfied. Therefore, the second configuration condition in Embodiment 3 is rewritten to Expression (72) where n is an integer of 2 or more from Expression (11), and the relational expression of γ=2γ1+γ2is rewritten to Expression (73). The second configuration condition of Expression (72) can be established for a freely-selected integer n equal to or more than 2 by adjusting the number of the vanes Nv. However, in this structure example, γ=θ2=θ4=2π/3 (120°) and α=π/3 (60°) are satisfied. Therefore, n=2 is satisfied, and the second configuration condition is satisfied in the form of Expression (74).
[Expression 72]
γ=n·α(72)
[Expression 73]
γ=2γ1(73)
[Expression 74]
γ=2α  (74)

In the structure example of Embodiment 3, the number of vanes is six, and hence there are always six working chambers of which phases are shifted from each other by α=2π/6 (60°) as shown inFIG.31.FIG.32shows the change of the front area S(θr) of each working chamber when the above is in the suction stroke as a function of the rotor rotation angle θr. The number of the suction working chambers each in the position of a certain θrin the horizontal axis is always three, the front areas thereof are shown by S1to S3in the drawing, and the calculation result of the total area St(θr) is also shown. The differential value dSt/dθrof the total area St(θr) by the rotor rotation angle inFIG.32is shown inFIG.33as the pump flow-rate fluctuation pattern on the suction side, but it can be understood that the differential value dSt/dθris a fixed value in the entire range of the rotor rotation angle θr, and the fluctuation of the pump flow rate Qd(t) on the suction side can also be caused to be zero in the structure example of Embodiment 3. It is understood that, when the pump flow-rate fluctuation pattern on the discharge side is calculated by an equivalent procedure, the pump flow-rate fluctuation pattern also becomes a fixed value and the fluctuation of the pump flow rate Qd(t) on the discharge side can also be caused to be zero.

The reason the fluctuation of the pump flow rate Qs(t) on the suction side in the structure example of Embodiment 3 also becomes zero is explained below with use of expressions. In Embodiment 3, there is a relationship of Expression (73) and γ2=0°, and hence the following is obtained when Expression (4) to Expression (9) are rewritten with use of the rotor rotation angle θ (θ=θr−θ1) of the starting end reference of the interval. First, in Expression (4) to Expression (6) of the second interval that is the suction stroke, the interval of Expression (5) is removed and the intervals of Expression (4) and Expression (6) are connected. Expression (4) and Expression (6) become the same expressions. As a result, L(θ) indicating the rotor slit direction position of the vane distal-end circular-arc center point is integrated to one Expression (75) in one continuous interval. Similarly, also in Expression (7) to Expression (9) of the fourth interval that is the discharge stroke, the interval of Expression (8) is removed, and L(θ) of the intervals of Expression (7) and Expression (9) is integrated to one Expression (76) in one continuous interval.

[Expression⁢75]L⁡(θ)=Lmax-Lminγ·θ-Lmax-Lmin2⁢π·sin⁡(2⁢π⁢θγ)+Lmin(75)
in the entire region of the second interval θ≤θ<γ

[Expression⁢76]L⁡(θ)=-Lmax-Lminγ·θ-Lmax-Lmin2⁢π·sin⁡(2⁢π⁢θγ)+Lmax(76)
in the entire region of the fourth interval θ≤θγ

In the structure example of Embodiment 3, both of the number of the working chambers in the suction stroke and the number of the working chambers in the discharge stroke are always three as shown inFIG.32and are the same to that in the suction stroke inFIG.13and the discharge stroke inFIG.16in the first structure example of Embodiment 1. Therefore, the pump flow rate Qs(t) on the suction side in the structure example of Embodiment 3 is expressed by Expression (77) that is the same as Expression (17) in the first structure example of Embodiment 1. The first configuration condition of Expression (10) is also satisfied in the structure example of Embodiment 3. Therefore, a first term in the curly brackets on the right-hand side in Expression (77) is given by Expression (19), and a second term and a fifth term are given by Expression (22) as with the first structure example of Embodiment 1.

[Expression⁢77]Qs(t)=W·ω·{dSs⁢0d⁢θr-dSs⁢1d⁢θr-dSs⁢2d⁢θr-dSs⁢3d⁢θr-dSs⁢4d⁢θr}(77)

A third term and a fourth term in the curly brackets on the right-hand side in Expression (53) are calculated by Expression (78) and Expression (79), respectively, by giving the functional forms of the position L(θ) in the slits of the vanes by Expression (75), performing differentiation by θ, and performing multiplication by the vane thickness T, and the total thereof becomes a fixed value of Expression (80).

[Expression⁢78]-dSsv⁢2d⁢θr=-T·dL⁡(θ)d⁢θ=-T·Lmax-Lminγ+T·Lmax-Lminγ·cos⁡(2⁢π⁢θγ)(78)[Expression⁢79]-dSsv⁢3d⁢θr=-T·dL⁡(θ+α)d⁢θ=-T·Lmax-Lminγ+T·Lmax-Lminγ·cos⁡(2⁢π⁢θ+αγ)=-T·Lmax-Lminγ+T·Lmax-Lminγ·cos⁡(2⁢π⁢θγ+π)(79)[Expression⁢80]-dSsv⁢2d⁢θr-dSsv⁢3d⁢θr=-T·Lmax-Lminα(80)

Expression (19), Expression (22), and Expression (80) are assigned to Expression (77), and the pump flow rate Qs(t) on the suction side in the structure example of Embodiment 3 is obtained as a fixed value on the right-hand side in Expression (81). As a result, it can also be proved that the fluctuation of the suction-side pump flow rate theoretically becomes zero, and it can also be verified that the pump flow-rate fluctuation pattern dSt/dθrinFIG.33becomes a fixed value in the structure example of Embodiment 3. The value obtained by dividing Qs(t) on the suction side of Expression (81) by W·ω becomes dSt/dθrinFIG.33. The value calculated with use of various dimensions of the structure example of Embodiment 3 is 124.80 and exactly matches with the fixed calculation value inFIG.33.

[Expression⁢81]Qs(t)=W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(81)

The pump flow rate Qd(t) on the discharge side in the structure example of Embodiment 3 is obtained as a fixed value on the right-hand side in Expression (82) when the functional form of L(θ) is not given by Expression (28) and Expression (30) and is always given by Expression (76) in a procedure that derives Expression (42) in the first structure example of Embodiment 1. As a result, it is proved that the fluctuation of the discharge-side pump flow rate also theoretically becomes zero in the structure example of Embodiment 3.

[Expression⁢82]Qd(t)=-W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(82)

In Embodiment 3, the second configuration condition of a general structure including not only the structure examples shown inFIG.30andFIG.31but also other structure examples is Expression (72), and θ2of the second interval and θ4of the fourth interval inFIG.30equivalent to γ are n times of the angle α between the adjacent rotor slits. Here, n represents an integer of 2 or more. At this time, for example, the number of the vanes in the second interval is n, and hence Expression (83) is obtained when Expression (77) is rewritten to a general form using n. The general structure of Embodiment 3 also satisfies the first effect element of Expression (10), and hence a first term in the curly brackets on the right-hand side becomes Expression (19), and a second term and the final term become Expression (84).

[Expression⁢83]Qs(t)=W·ω·{dSs⁢0d⁢θr-dSsv⁢1d⁢θr-∑m=1ndSsv⁡(m+1)d⁢θr-dSsv⁡(n+2)d⁢θr}(83)[Expression⁢84]-dSsv⁢1d⁢θr=-dSsv⁡(n+2)d⁢θr=0(84)

A sum total of a third term in the curly brackets in Expression (83) is rewritten to Expression (85) as follows, and hence Expression (86) is obtained by giving the functional form of L(θ) by Expression (75), performing differentiation is by θ, performing multiplication by the vane thickness T, and using the relationship of γ=nα in Expression (72).

[Expression⁢85]-∑m=1ndSsv⁡(m+1)d⁢θr=-T⁢∑m=1ndL⁡(θ+(m-1)⁢α)d⁢θ(85)[Expression⁢86]-∑m=1ndSsv⁡(m+1)d⁢θr=-n·T·(Lmax-Lmin)γ+T·(Lmax-Lmin)γ⁢∑m=1ncos⁡(2⁢π⁢(θ+(m-1)⁢α}γ)=-n·T·(Lmax-Lmin)γ+T·(Lmax-Lmin)γ⁢∑m=1ncos⁡(2⁢π⁢θγ+2⁢πn⁢(m-1))(86)

A sum total portion on the right-hand side in Expression (86) is a sum of an X coordinate of mass points M1to Mn of which number is changed from 2n1to n and which are the same in mass and are disposed at even intervals on a circle having a radius of 1 about a center of the origin O shown inFIG.29and becomes an X coordinate of the center of gravity thereof when being divided by n. As withFIG.29, the center of gravity is in the origin, and hence Expression (87) is always established. The sum total term in the curly brackets in Expression (83) becomes a fixed value on the rightmost-hand side in Expression (88) in the end because γ-nα is satisfied in the general structure of Embodiment 3.

[Expression⁢87]∑m=1ncos⁡(2⁢π⁢θγ+2⁢πn⁢(m-1))=0(87)[Expression⁢88]-∑m=1ndSsv⁡(m+1)d⁢θr=-n·T·(Lmax-Lmin)γ+T·(Lmax-Lmin)α(88)

The pump flow rate Qs(t) on the suction side in the general structure of Embodiment 3 also becomes a fixed value given by Expression (89) by assigning Expression (19), Expression (84), and Expression (88) to Expression (83). The discharge-side pump flow rate Qd(t) in the general structure of Embodiment 3 is also obtained as a fixed value on the right-hand side in Expression (90) by a procedure similar to that of the suction side.

[Expression⁢89]Qs(t)=W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(89)[Expression⁢90]Qd(t)=-W·ω·(Rmax2-Rmin22-T·Lmax-Lminα)(90)

As a result of the above, in the general structure of Embodiment 3, it is also proved that the fluctuation of the pump flow rate theoretically becomes zero by satisfying the first configuration condition of Expression (10) in the present invention, also satisfying the second configuration condition of Expression of Expression (11) by satisfying Expression (72), giving the vane position L(θr) by the functional forms based on Expression (4) to Expression (9), and also satisfying the third configuration condition. The general structure of Embodiment 3 is also particularly characterized in being advantageous in terms of speed-up because the inertial force can be reduced by increasing n in Expression (72), expanding the radial-direction movement interval of the vanes, and causing the vanes to slowly advance and retreat.

In all of the structure examples in each embodiment of the present invention, calculation expressions of the pump flow rates Qs(t) and Qd(t) for one suction port and one discharge port have different signs due to the difference between suction and discharge, but are expressions that give fixed values of which absolute values are equal to each other. When each Qs(t) and each Qd(t) are compared with each other between different structure examples, completely equal expressions are obtained. In one rotary-vane-type hydraulic pump, there is one way for numerical values of various symbols on the right-hand side in each expression. Therefore, even when structure examples are selected and combined for each of the sides of the suction side and the discharge, the flow rates on the suction side and the discharge side match and the continuity is maintained when the numbers of the pairs of the suction port and the discharge port are equal to each other. In other words, in the present invention, the rotary-vane-type hydraulic pump with a small pressure pulsation can be configured by combining freely-selected two out of all conceivable structure examples.

All of the embodiments of the present invention are in common with each other in that the embodiments satisfy Expression (10) relating to the relationship between the angle of the circular arc portion of the cam ring and the angle between the vane slits as the first configuration condition of the invention and satisfy common Expression (11) relating to the relationship between the angle in each interval and each portion in which the vanes move in the radial direction and the angle between the adjacent vane slits as the second configuration condition of the invention. Expression (11) is rewritten to Expression (12) in Embodiment 1, is rewritten to Expression (48) and Expression (49) in Embodiment 2, and is rewritten to Expression (72) in Embodiment 3. The third configuration condition of the invention is satisfied by giving the motion of the vanes by an expression based on Expression (4) to Expression (9). Expression (4) to Expression (9) are rewritten to Expression (24) to Expression (26) and Expression (28) to Expression (30) in Embodiment 1, are rewritten to Expression (52) to Expression (54) in Embodiment 2 as an example of the suction side portion, and are rewritten to Expression (75) and Expression (76) in Embodiment 3.

In each embodiment of the present invention, it becomes possible to cause the theoretical pump flow rates on the suction side and the discharge side to be perfect fixed values, cause the flow rate fluctuation to be zero, and significantly reduce the pressure pulsation by satisfying all of the related relational expressions of each embodiment. However, even when the pump flow rate is not a perfect fixed value, the object of the present invention to reduce the pressure pulsation can be achieved to a certain degree when the flow rate fluctuation can be reduced. In that sense, not all of the relational expressions need to be satisfied and only some may be satisfied, and each relational expression only needs to be substantially established even when the relational expressions are not completely established.

As a specific case, it is most desired that β be within a range expressed by Expression (10). However, the change in the distance from the rotor center in the vicinity of the interval of β of the cam ring is minute, and hence the effect of reducing the flow rate fluctuation is considerably obtained when β is within a range that is 0.9 times of a or more and is close to Expression (10) even when β is outside the range. It is most desired that the left-hand side and the right-hand side in each of the expressions of Expression (12), Expression (48), Expression (49), and Expression (72) match with each other, but the effect of reducing the flow rate fluctuation can be obtained as well when the left-hand side is a close value within a range of 0.9 times to 1.1 times of the right-hand side even when the left-hand side and the right-hand side do not completely match with each other.

In particular, even when Expression (4) to Expression (9) that give forms of the motion of the vanes in the slit direction in accordance with the rotor rotation in all of the structure examples as the third configuration condition of the invention and each expression rewritten for each embodiment are not exactly established, a motion similar to those expressions only need to be given to the vanes. The motion of the vanes in the slit direction does not necessarily need to be directly defined, and a cam ring profile that gives a similar motion to the vanes may be defined. At this time, it becomes possible to determine what kind of motion of the vanes is a motion equivalent to the above and what kind of a cam ring profile can give the similar motion to the vanes by analyzing features of the functional forms of Expression (4) to Expression (9) that are basic expressions that define the motion form of the vanes.

Expression (4), Expression (6), Expression (7), and Expression (9) out of Expression (4) to Expression (9) described above are expressions that define the motion form of the vanes by intervals in which the function L(θr) becomes a curve. Those expressions are all characterized in being a functional form including a periodic function of which period is the interval γ1+γ3=2γ1. Here, the functional form of L(θr) inFIG.30of Embodiment 3 is taken as a specific example and is compared with another functional form that does not have the feature described above. Embodiment 3 is different from the other embodiments and does not have portion intervals in which L(θr) linearly changes in the second interval and the fourth interval, and hence L(θr) becomes a curve in the entirety of those intervals. Here, L in those intervals is given by Expression (75) and Expression (76) with use of θ that is zero in the starting ends of the intervals where θ=θr−θ1is satisfied in the second interval and θ=θr−θ1−θ2−θ3is satisfied in the fourth interval. However, those functional forms include periodic functions of which period is γ1(=2γ1) that is an interval in which L(θ) is a curve and has the feature described above as well.

FIG.34shows a motion form example of the vanes that do not have the third configuration condition of the present invention. Here, L of the second interval and the fourth interval inFIG.34is given by Expression (91) and Expression (92) with use of θ that is zero at the starting end of the intervals as well. The period of the periodic function in those expressions is 2γ and is obviously different from Expression (75) and Expression (76), but a term of a linear function of θ is added besides terms of the periodic function in Expression (75) and Expression (76), and L(θr) inFIG.30and L(θr) inFIG.34look similar in that both smoothly connect the minimum value and the maximum value to each other. However, the difference becomes obvious when the above is differentiated by θr.

[Expression⁢91]L⁡(θ)=-Lmax-Lmin2·cos⁡(2⁢π⁢θ2⁢γ)+Lmax-Lmin2(91)in the entire region of the second interval 0≤θ<γ

[Expression⁢92]L⁡(θ)=Lmax-Lmin2·cos⁡(2⁢π⁢θ2⁢γ)+Lmax-Lmin2(92)in the entire region of the fourth interval 0≤θ<γ

In each of the second interval and the fourth interval in which the vanes perform the movement in the radial direction, dL/dθrinFIG.35obtained by differentiating L(θr) inFIG.34by θrbecomes a half-period of a periodic function of which period is 2γ(=4γ1) that is twice as much as the interval by Expression (91) and Expression (92), and dL/dθrbecomes a function which does not have an inflection point on the inside of interval and in which gradients on both ends of the interval do not become zero. Meanwhile, in both of the second interval and the fourth interval, dL/dθrinFIG.36obtained by differentiating L(θr) inFIG.30of the present invention by θrbecomes one period of a periodic function of which period is the interval, and dL/der becomes a function which has two inflection points the inside of the interval and in which the gradient becomes zero on both ends of the interval. The motion of the vanes in the third configuration condition of the present invention is characterized in that dL/dθrhas gradients that become zero on both ends and two inflection points on the inside, and it can be confirmed that a similar motion is given to the vanes by confirming the feature.

FIG.37shows a cam ring inner-circumference profile54athat causes the movement of the vanes inFIG.30by polar coordinates in which an origin that is the center of the rotor52is the pole and the X-axis is the initial side. The distance R from the origin that is a point on the inner circumferential profile54ais indicated as a function of a deflection angle θp with respect to the X-axis.FIG.38is a diagram showing a curve obtained by differentiating R(θp) inFIG.37by θp. The change of R(θp) and dR/dθpinFIG.37andFIG.38with respect to θpis substantially in the same tendency as the change of L(θr) and dL/dθrinFIG.30andFIG.36with respect to θr, and it can be understood that the feature of the motion form of the vanes also appears in the feature of the cam ring inner-circumference profile.

In particular, a feature in which dR/dθphas gradients that become zero on both ends of the interval and has two inflection points on the inside of the interval in the interval of θpcorresponding to the second interval and the fourth interval in which the vanes perform movement in the radial direction inFIG.38can be confirmed. Therefore, it can be confirmed that a motion similar to the motion form of the vanes that is the third configuration condition of the present invention is given to the vanes also by confirming that the cam ring inner-circumference profile itself has this feature. The confirmation of whether the given cam ring inner-circumference profile has the feature is easier with dR/dθpbecause only the shape of the cam ring alone needs to be measured as compared to dL/dθrwhere the relationship between θrand L(θr) needs to be actually measured while the rotor is rotated in a pump assembled state.

In each structure example of the present invention, there are structure examples in which there is the offset Ofin the rotor slit as in the first structure example and the third structure example of Embodiment 1 and the structure example of Embodiment 3 and structure examples in which there are no offsets (Of=0) as in the second structure example of Embodiment 1 and the structure example of Embodiment 2, but Ofis not included in expressions that give Qs(t) and Qd(t) that are the pump flow rates of each structure example as a variable. This means that present invention exhibits effects by the first to third configuration conditions regardless of whether there is the offset Of. The rotors in each structure example of the present invention have an outer circumference surface having a cylindrical shape, but a rotor having any outer circumference surface shape may be used in the present invention. This is because the volume of each working chamber is only changed by a fixed amount that is the amount of a difference in the outer circumference surface shape, and hence the change pattern of the pump flow rate is not different from that in each structure example of the present invention.

In each embodiment of the present invention, the cam ring position is fixed with respect to the rotor rotation center position, but the present invention can also be applied to a variable capacity structure that can change the flow rate for one rotor rotation by moving the cam ring position with respect to the rotor rotation center position. When some of the configuration conditions of the present invention are satisfied when the cam ring is in a certain position with respect to the rotor rotation center position, effects similar to those of each embodiment of the present invention are obtained in that position or a position in the vicinity of the position.

Lastly, the rotary-vane-type hydraulic pump is provided in all of the structure examples of the embodiments of the present invention above, but the present invention functions as a hydraulic motor when those suction side and discharge side are caused to be opposite and a high-pressure working fluid is supplied. When any of the structures in each structure example of the present invention is applied at this time, effects in which the flow rate fluctuation on the suction side and the discharge side of the hydraulic motor becomes minute, for example, is obtained in a completely similar manner as the case of the hydraulic pump. In other words, the present invention is also applicable to a rotary-vane-type hydraulic motor.

INDUSTRIAL APPLICABILITY

According to the present invention, the present invention can be used in manufacturing industries and the like of a displacement hydraulic pump, a hydraulic motor, and the like.

REFERENCE SIGNS LIST

1,11: shaft member,2,12,22,32,42,52: rotor,2a,12a: rotor slit,3,13,23,33,43,53: vane,4,14: cam ring,4a,14a,24a,34a,44a,54a: cam ring inner-circumference profile,4b: pump inflow port,4c: pump outflow port,5: side plate F,5a,15a,25a,35a,45a,55a: suction port F,5b,15b,25b,35b,45b,55b: discharge port F,5c,15c: back pressure groove F,6: side plate R,6a,16a,26a,36a,46a,56a: suction port R,6b,16b,26b,36b,46b,56b: discharge port R,6c,16c: back pressure groove Rθr: rotor rotation angle with reference to X-axis positive directionθ: rotor rotation angle based on position in which vane distal end comes into contact at starting end of radial-direction movement intervalω: angular velocityt: timeRv: radius of vane distal end circular arcP0: center point of vane distal end circular arcO: rotor center pointOf: offset amount from rotor center of P0to opposite rotation side in direction perpendicular to rotor slitL: rotor-slit-direction distance between rotor center point O and center point P0of vane distal end circular arcLmin: minimum value of LLmax: maximum value of Lθ1to θ5: change amount of θrin each interval sectioned in accordance with change state of Lα: angle between adjacent rotor slitsβ: change amount of θrin interval in which L is fixed values such as Lminand Lmaxγ: change amount of θrin intervals such as θ2and θ4in which vane performs radial-direction movementγ1: change amount of θrin first portion in interval of θrof change amount γγ2: change amount of θrin second portion in interval of θrof change amount γγ3: change amount of θrin third portion in interval of θrof change amount γα′: angle between rotor slits of two vanes sandwiching second portionNv: number of vanesn: integer of 2 or more by factor of γ with respect to αn1: natural number that is common factor of γ1and 13 with respect to αn2: natural number that is factor of γ2with respect to αS, Sn: front area of working chamber in suction stroke or discharge stroke and area identified by applying numbers to all working chamber front areas in corresponding stroke at same timeSt: total of all working chamber front areas in one suction stroke or discharge stroke at same timeW: thickness of cam ringT: thickness of vaneDr: diameter of rotorRr: rotor outer circumference radiusDc: diameter of cam ring inner circumference having perfect circle profileR: distance of point on cam ring inner circumference profile from rotor center (origin)θp: deflection angle of which initial side is X-axis of point on cam ring inner circumference profileRmax: maximum value of RRmin: minimum value of RQs: pump flow rate on suction side by one suction stroke portionQd: pump flow rate on discharge side by one discharge stroke portionM1to M2n1: number of 2n1mass points that is same in mass point and disposed at even intervals on circumference having radius of 1 shown inFIG.29Pi-j: contact point between cam ring inner circumference and vane in boundary between i-th interval and j-th interval of θrPk-l-m: contact point between cam ring inner circumference and vane in boundary between l-th portion and m-th portion in k-th interval of θrSs1, Ss2, Ss3: front area of each working chamber on suction side shown by hatching inFIG.13andFIG.16Sd1, Sd2, S3d: front area of each working chamber on discharge side shown inFIG.13andFIG.16Ss0: front area of suction side portion shown by hatching inFIG.14andFIG.17Sd0: front area of suction side portion shown by hatching inFIG.14andFIG.17Ssv1, Ssv2, Ssv3, Ssv4: front area of each vane distal end portion on suction side shown by hatching inFIG.15andFIG.18Ssv5: front area of fifth vane distal end portion on suction sideSdv1, Sdv2, Sdv3, Sdv4: front area of each vane distal end portion on discharge side shown by hatching inFIG.15andFIG.18Vst: total of volumes of all working chambers in suction strokeVdt: total of volumes of all working chambers in discharge stroke