JP5550414B2 - Coolant pump - Google Patents

Description

The present invention relates to a coolant pump used when supplying a coolant liquid for lubrication from a coolant liquid tank to a processing site such as metal in a machine tool or the like.

In an environment where cavitation is likely to occur due to factors such as low effective NPSH (absolute suction lift) of the pump usage environment or high required NPSH of the pump being used when using the centrifugal impeller, the impeller is subject to erosion. It is well known that erosion of the impeller causes damage to the impeller.

As a countermeasure against this erosion, a method of suppressing the occurrence of cavitation in the centrifugal impeller by placing an inducer impeller at the suction port of the centrifugal pump and increasing the pressure is adopted. Cavitation occurs in the inducer impeller itself, but due to its blade shape and fluid characteristics, unlike the centrifugal impeller, it has features such that it is difficult to pump water and erosion is unlikely to occur. The design of the inducer impeller disposed at the suction port of the centrifugal pump focuses on the durability as an erosion countermeasure or the elimination of unstable phenomena such as surging due to the backflow vortex.

Such an inducer impeller has a general shape similar to that of a mixed flow pump, and a plurality of (two to three) helical blades are arranged in a spiral symmetrically around the boss. Has been.

As described above, the inducer impeller is originally used by being arranged on the suction side of an impeller of a centrifugal pump or the like. However, in this application, the term “inducer impeller” is particularly limited. If not, helical blades are spirally fixed on the outer peripheral surface of the boss rotating around its center line, and the specific speed described later at the point where the hydraulic efficiency is the highest is in the category of the mixed flow pump. It means something that belongs, and may not necessarily be installed on the inlet side of another impeller.

Patent Document 1 describes a typical coolant pump, which is provided with a semi-open impeller to prevent foreign matter such as chips from accumulating in a casing inside the pump, and the casing has a coolant flow path. The structure is such that the flow rate of the coolant liquid passing through the inside is increased by reducing the area. Therefore, the remaining of foreign matters such as swarf in the casing is suppressed.

However, in this pump, the coolant liquid sucked into the casing flows into the swirl chamber through the impeller, and is then guided to the swirl chamber while being pressed against the side wall of the swirl chamber, and is pumped toward the discharge port. However, the accumulation of foreign matters such as chips is not sufficiently suppressed.

On the other hand, as a pump using a single inducer, Patent Document 2 describes a pump including an inducer impeller rotated around a horizontal line. Since this pump is intended to pump water in the irrigation channel in the horizontal direction, the inducer impeller inevitably has a large amount of treated water and a low head.

However, in the coolant pump, a smaller amount of processing liquid is required, but a specification having a high head is required, and the pump disclosed in Patent Document 2 cannot be used as a coolant pump.

JP 2009-299596 A JP 2003-239898 A

The inducer impeller has a helical blade fixed on the outer peripheral surface of the boss, and the shape of the impeller approximates that of an axial flow pump. Even if cavitation occurs, it has the property that it is difficult to pump up water like a centrifugal pump.
The present invention inherits the above-described properties of the inducer impeller pump, simplifies the structure compared to conventional centrifugal pumps, and enables a significant cost reduction. An object of the present invention is to provide a coolant pump that can prevent the accumulation of foreign matter.

A coolant pump according to the present invention is a coolant pump that sucks up coolant liquid, and includes a pump casing having a cylindrical inner space in which a coolant liquid outlet is formed at an upper portion and a coolant liquid suction port is formed at a lower end, A single inducer impeller for generating the full head of the pump in the pump casing, wherein the inducer impeller is fixed with a plurality of helical blades on the outer periphery of the boss portion, and an outlet angle for each helical blade; Is set to be 2 degrees or more larger than the entrance angle.

According to the present invention, it is possible to generate a normal head required as a coolant pump. In addition, since the inducer impeller causes the head to be expressed by the wing action, performance degradation such as inability to lift water is less likely to occur compared to a conventional coolant pump using a centrifugal impeller. The flow of coolant is similar to that of a mixed flow pump impeller, and the coolant flow path in the pump casing can be made wider and less bent than in the case of a centrifugal pump. Therefore, it is possible to suppress a phenomenon in which foreign matters such as chips flowing into the pump casing mixed with the coolant liquid accumulate in the pump casing. Further, the structure of the pump casing can be simplified as compared with the conventional coolant pump in which the centrifugal impeller is used, and the manufacturing cost can be greatly reduced.

In addition, by setting the radial clearance between the inducer impeller and the inner peripheral wall surface of the pump casing to be larger than 1% of the outer diameter of the inducer impeller, the pump is driven by the rotational energy of the inducer impeller. The coolant liquid existing in the area below the inducer impeller in the inner space of the casing is swirled, and the swirling is further efficiently propagated to the coolant liquid existing outside the pump casing through the liquid suction port. be able to. As a result, foreign matter such as chips contained in the coolant liquid is floated and flowed to the inducer impeller, and the foreign matter contained in the coolant liquid is prevented from precipitating and accumulating inside the coolant liquid container surrounding the pump casing. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall side view showing a coolant pump according to an embodiment of the present invention, most of which is a cross section. It is side surface sectional drawing which showed the principal part of the said coolant pump in detail. It is a perspective view of the inducer impeller of the said coolant pump. It is a side view of the inducer impeller. It is a systematic diagram which shows the usage example of the said coolant pump. It is a figure which shows the characteristic curve of the said coolant pump. It is a figure showing the relationship between a cavitation coefficient and a lift coefficient about the said coolant pump. It is a figure showing the relationship between a cavitation coefficient and a lift coefficient about the conventional coolant pump. It is sectional drawing for demonstrating the flow path of the conventional coolant pump. It is a figure which shows the relationship between an exit angle and a lift coefficient about the coolant pump shown in FIG. It is a figure which shows the relationship between the clearance gap between a pump casing and an inducer impeller, the leak amount from this clearance gap, and a lift coefficient about the coolant pump shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below with reference to the drawings.

<< Structure of the coolant pump of this embodiment >>
The coolant pump which is a present Example is provided with the pump casing 1, the inducer impeller 2, the rotating shaft 3, and the drive part 4, as shown in FIG.1 and FIG.2.
If it explains in full detail about each part, the pump casing 1 is formed with the upper casing 1a and the lower casing 1b. The upper casing 1a includes a straight pipe member 5 whose center line a1 is vertically oriented, a top plate 6 with the upper end surface of the straight pipe member 5 closed, and a flange fixed to the lower end of the peripheral wall portion 5a of the straight pipe member 5. A discharge pipe 8 is provided which communicates with a member 7a and a circular coolant outlet 5b formed in the vicinity of the upper end of the peripheral wall 5a and extends radially outward of the straight pipe member 5. The top plate 6 has a shaft sealing portion 9 for allowing the rotary shaft 3 to pass through in a rotatable and liquid-tight manner.

On the other hand, the lower casing 1b includes a straight pipe member 10 having a longitudinal center line a2 and a flange member 7b fixed to the upper end of the peripheral wall portion 10a of the straight pipe member 10, and an inner region at the lower end of the peripheral wall portion 10a. Is opened as a coolant inlet 10b.

The upper casing 1a and the lower casing 1b are coupled in an airtight manner through bolts b1, packings b2, and the like so that the center lines a1 and a2 are arranged in a single line in the vertical direction. As a result, a cylindrical internal space c <b> 0 including the inner region c <b> 1 of the straight pipe member 5 and the inner region c <b> 2 of the straight pipe member 10 is formed inside the pump casing 1. The straight pipe members 5 and 10 are preferably made by cutting an existing schedule pipe into a required length in order to reduce the manufacturing cost.

In FIG. 2, the height c10 from the lower end of the pump casing 1 to the center of the coolant outlet 5b is 350.5 mm, and the straight pipe member 5 and the straight pipe member 10 both have an outer diameter of 139.8 mm and an inner diameter of d1 is 130.5 mm.

The inducer impeller 2 includes a boss portion 11 and three helical blades 12 (see FIGS. 3 and 4). The boss portion 11 includes a blade holding portion 11a and a single tip portion 11b disposed below the blade holding portion 11a. The blade holding portion 11a has a tapered outer peripheral surface c01, and the blade leading edges c02 of the three helical blades 12a, 12b, and 12c are integrally coupled to the outer peripheral surface c01, and a step is formed at the center. It has an attached shaft insertion hole c03. The distal end portion 11b has an outer surface in a tapered semi-elliptical rotator shape, and has a nut portion c04 that is screwed to the distal male threaded portion 3a of the rotary shaft 3 at the center. The tip end portion 11b fixes the blade holding portion 11a to the rotary shaft 3 and exhibits a rectifying action that smoothens the flow of the coolant liquid that flows along the outer surface of the inducer impeller 2.

Although the number of helical blades 12 is actually preferably three as shown in the figure, it may be two or four or more. However, it is not preferable to use only one helical blade 12 in order to ensure balance and efficiency during rotation of the inducer impeller 2.

In this embodiment, there are three helical blades 12 in the inducer impeller 2 and they are fixed to the outer peripheral surface of the blade holding part 11a at equal angular intervals around the center line a3. Each of the helical blades 12a, 12b, and 12c is fixed in a state in which a strip is spirally wound around the outer peripheral surface of the blade holding portion 11 over a range of, for example, 250 degrees to 360 degrees around the center line a3. Each helical wing 12a, 12b, 12c has a center line (blade thickness center line) a4 connecting the center points in the center line direction length of the blade cutting surface when cut by a plane (radial surface) including the center line a3. It is positioned so as to be a straight line orthogonal to a3. At this time, the blade thickness center line a4 does not necessarily have to be orthogonal to the center line a3 in order to improve the strength or hydraulic performance, and the front surface (positive pressure surface) and rear surface of the helical blade 12 ( The negative pressure surface may be bent in a slight arc shape. The helical blades 12a, 12b, and 12c may have a uniform rotational radial height from the front end of the inlet portion f1 to the rear end of the outlet portion f2, or hydraulic loss and stress in the vicinity of the inlet portion f1 and the outlet portion f2. The concentration may be changed so as to reduce the concentration. In this embodiment, the height is designed to be smaller as the tip is approached in the vicinity of the inlet portion f1.

Further, as shown in FIG. 3, the angle (inlet angle) θ1 of the inlet portion f1 of each helical blade 12a, 12b, 12c of the inducer impeller 2 is set to 7 degrees. Here, the inlet angle θ1 is a small length portion at the inlet portion f1 at the representative position of each helical blade 12a, 12b, 12c (for example, the blade leading edge c02 of the helical blades 12a, 12b, 12c) and the center line a3. The crossing angle with an orthogonal plane.

On the other hand, the angle (exit angle) θ2 of the outlet portion f2 of each helical blade 12a, 12b, 12c of the inducer impeller 2 is set to 9 degrees. Here, the exit angle θ2 is a small length portion at the exit portion f2 at the representative position of each helical blade 12a, 12b, 12c (for example, the blade leading edge c02 of the helical blades 12a, 12b, 12c) and the center line a3. The crossing angle with an orthogonal plane.
From the front end of the inlet portion f1 of each helical blade 12a, 12b, 12c to the rear end of the outlet portion f2, a minute length portion at an arbitrary point on the blade leading edge c02 of the helical blade 12a, 12b, 12c, and the center line The coupling is smoothly performed so that the crossing angle with respect to the plane orthogonal to a3 gradually increases.

Further, as shown in FIG. 4, the inducer impeller 2 has an outer diameter d2 of the helical blade 12 of 129.6 mm, an inlet side diameter of the hub portion 11 (inlet hub diameter) of 51.91 mm, The outer diameter of the inlet side is 77.48 mm, the thickness of the helical blades 12a, 12b, 12c is 3.87 mm, and the length of the helical blades 12a, 12b, 12c in the direction of the center line a3 is the outer diameter d2 of the helical blade 12 The rotational speed is set to 3500 rpm, and the inlet flow coefficient is set to 0.0046.

As shown in FIGS. 1, 2, and 4, the rotation shaft 3 is an output shaft of the drive unit 4, and a first small-diameter portion 3 c is formed at a lower portion via a first step portion 3 b. Further, a second small diameter portion 3e is formed on the lower side via a second step portion 3d, and a male screw portion 3a is formed on the lower side of the second small diameter portion 3e via a third step portion 3f. Yes. The first small diameter portion 3c is inserted into the large diameter portion of the shaft insertion hole c03 of the blade holding portion 11a, the second small diameter portion 3e is inserted into the small diameter portion of the shaft insertion hole c03, and the second The step portion 3d abuts against the step portion of the shaft insertion hole c03 to restrict the upward displacement of the blade holding portion 11a. The male screw portion 3a protrudes below the shaft insertion hole c03 of the blade holding portion 11a, and the tip end portion 11b is screwed in a fastening manner via the nut portion c04, so that the blade holding portion 11a is fixed to the lower end of the rotary shaft 3. It is positioned. Key grooves are formed in each of the outer peripheral surface of the second small diameter portion 3e and the inner peripheral surface of the small diameter portion of the shaft insertion hole c03 of the blade holding portion 11a, and the key c05 is fitted between these key grooves. The relative rotation between the blade holding part 11a and the rotary shaft 3 is restricted. A height c20 (FIG. 2) from the lower end of the pump casing 1 to the tip of the inlet portion f1 of the helical blade 12 of the inducer impeller 2 is 57.3 mm.

The drive unit 4 is formed of an electric motor. The electric motor 4 is coupled to the upper casing 1 a via an intermediary block part 13 and a bolt b <b> 2 and is integrated with the pump casing 1.

<< Usage example of coolant pump of this embodiment >>
Next, the usage example of the coolant pump of a present Example is shown.
As shown in FIG. 5, a portion below the coolant liquid outlet 5 b of the pump casing 1 is fixed so as to be positioned inside a coolant liquid tank 14 such as a machine tool. In the coolant liquid tank 14, the coolant liquid g is stored up to above the inducer impeller 2.
The supply line 15 is formed by extending the discharge pipe 8, and the tip of the supply line 15 is guided to a metal machining point 16 of the machine tool. In the middle of the supply line 15, a filtering device 17 is provided for scavenging foreign matters such as chips mixed in the coolant liquid g fed from the coolant pump 100. A discharge line 18 is provided between the lower part of the metal machining point 16 and the coolant liquid tank 14 and the coolant liquid g that has been supplied to the metal machining point 16 and dropped and flows down naturally and returns to the coolant liquid tank 14. It is formed.

Under this condition, when the coolant pump 100 is operated, the coolant liquid g in the coolant liquid tank 14 is sent out by the liquid feeding action of the inducer impeller 2 rotated by the drive unit 4, and the metal machining point 16. Then, it returns to the coolant liquid tank 14 together with the chips by passing through the discharge line 18.

The coolant liquid g returning in this way can remove foreign matters such as chips having a particle diameter of 2 mm or more in the process of flowing into the discharge line 18, and thereby the particle diameter of 2 mm or less in the coolant liquid tank 14. Intrusion of chips and the like is avoided.

In the coolant pump 100 of the present embodiment, during the operation, the single inducer impeller 2 generates the entire pump head.

<< Results of Performance Test of Coolant Pump 100 of Example and Actions Related to Its Characteristics >>
The performance test result of the coolant pump 100 will be described below with reference to FIG.
In FIG. 6, the horizontal axis represents the flow coefficient φ, which is calculated by the following equation (1).
φ = Q / Dt ² · Ut ··· Formula (1)
Here, Q is the flow rate (m ³ / s), Dt is the outer diameter (m) of the helical blade 12, and Ut is the peripheral velocity (m / s) of the helical blade 12.

The vertical axis represents the head coefficient ψ and pump efficiency η (%), and this head coefficient ψ is calculated by the following equation (2).
ψ = gH / Ut ² ... Formula (2)
Here, g is a gravitational acceleration (m / s ² ), and Ut is a peripheral speed (m / s) of the helical blade 12.

In FIG. 6, the relationship between the flow coefficient φ and the pump efficiency η is represented by a curve e1, and the relationship between the flow coefficient φ and the head coefficient ψ is represented by a curve e2.
In FIG. 6, the magnitude of the flow coefficient φ representing the flow rate in the standard use state (in the normal use state, generally a design point) is a numerical value in the range of 0.02 to 0.03. There is a size corresponding to the position of the vertical line e3. In this standard use state, the specific speed Ns (m ³ , min, m) is about 550. The size of the lift coefficient ψ at the position where the specific speed is 550 is in the range of 0.20 to 0.25, and the lift is about 8.5 m.

At this time, the inducer impeller 2 has a rotational speed of about 3500 rpm and a flow rate of 0.6 m ³ , but these values almost coincide with the corresponding values of the existing coolant pump equipped with the centrifugal impeller. Yes.

Further, according to the curve e1, the pump efficiency η at the point where the specific speed Ns becomes 550 is about 30%. The value of 30% is lower than the efficiency of an existing coolant pump equipped with a conventional centrifugal impeller is 50%. This is shown in FIG. 2 near the coolant outlet 5b. As shown by the phantom line, the rotation restriction plate 19 for the coolant liquid g is provided or the flow path shape in the pump casing 1 is improved. Here, the turn restricting plate 19 is a flat plate and extends in the vertical direction, and is not intended to bend the flow path to 90 degrees or more.

The curve e2 shows that the lift coefficient ψ increases as the flow coefficient φ decreases. This is because the flow coefficient φ is from the position of the numerical value “0.04” to the minimum numerical value “0”. Even when used at any point, it shows that it works without inducing surging.
On the other hand, in the conventional coolant pump provided with the centrifugal impeller, when the flow coefficient φ is small, the lift coefficient ψ decreases as the flow coefficient φ decreases. In comparison with the coolant pump 100 of this embodiment, surging is likely to occur.

In FIG. 6, e01 is a curve that represents the efficiency when the impeller shape is the same and the surrounding environment is different, and e02 is a curve that represents the lift coefficient when the impeller shape is the same and the surrounding environment is different. It is. Here, there is a difference as compared with the curves of e1 and e2, because the swirl of the coolant liquid g occurs on the suction side, thereby promoting the reverse flow with respect to the liquid feed of the pump 100. This is because the coolant fluid g that has flowed back is again sucked into the pump 100 and the lift is raised.

<< Other Actions Performed by Coolant Pump 100 of This Example >>
In the coolant pump 100 of the present embodiment, when the relationship between the cavitation coefficient and the head coefficient was tested in a plurality of states having different flow coefficients φ, a point h1 at which the head decreased by 3% as shown by a curve e4 in FIG. Even if it passes, the lift coefficient ψ will not drop sharply. Here, each curve e4 from e4 (1) to e4 (6) corresponds to a different flow coefficient φ. On the other hand, when a similar test was performed on a conventional coolant pump equipped with a centrifugal impeller, as shown by a curve e5 in FIG. 8, when the cavitation occurred and the head began to drop, the head coefficient ψ dropped immediately. Then, the pumping becomes impossible. Here, each curve e5 from e5 (1) to e5 (6) corresponds to a different flow rate and impeller rotational speed. Thus, in the coolant pump 100 of the present embodiment, even if cavitation occurs, the lift coefficient ψ is less likely to be lower than that of a conventional coolant pump that includes a centrifugal impeller. The reason is that the centrifugal impeller applies force to the fluid by centrifugal force, whereas the inducer impeller 2 is based on the blade theory. The characteristic of the coolant pump 100 is that in the use as shown in FIG. 5, the coolant liquid g can be sucked and sent to the discharge side even when the coolant liquid g in the coolant liquid tank 14 becomes low level. As a result, the inducer impeller 2 can pump water if the tip of the helical blade 12 is immersed in the coolant liquid g even a little.

In the coolant pump 100, the pump casing 1 is formed by the straight pipe members 5 and 10, and the inducer impeller 2 belongs to the impeller of the diagonal flow pump. Therefore, the flow path through which the coolant liquid g flows is greatly bent. In addition, since the cross-sectional area of the flow path is relatively wide, the coolant liquid g is not easily deposited in the pump casing 1 during the pumping of the coolant liquid g. g is easily mixed and floated in a floating state. As a result, a situation in which a foreign object closes the flow path is prevented.

On the other hand, in the coolant pump provided with the conventional centrifugal impeller, as shown in FIG. 9, the coolant liquid that has entered the pump casing 21 from the suction port 20 as indicated by the arrow i1 is bent at 90 degrees while being centrifuge blades. The coolant liquid that flows into the narrow flow path 22a of the wheel 22 and flows out of the centrifugal impeller 22 flows into the spiral chamber 23 that is annularly arranged outside the suction port 20, as indicated by an arrow i2, and then As shown by the arrow i3, it flows into the discharge pipe 24 while bending upward at 90 degrees, moves upward, and flows out from the discharge port 25 as shown by the arrow i4. As described above, in the conventional coolant pump, the coolant liquid flows through a narrow flow path or a flow path bent in an S shape as a whole. Therefore, compared with the coolant pump 100, foreign matter such as chips in the pump casing 1. Is easy to deposit, and the flow path is likely to be blocked.

The coolant pump 100 also has a first reason that the inlet angle θ1 of the inducer impeller 2 is intentionally inconsistent with the relative angle of the coolant liquid g flowing into the inlet portion f1 with respect to the inducer impeller 2. And the gap c3 on the radius of the inner peripheral wall surface of the inducer impeller 2 and the inner space c0 of the pump casing 1 is set to be larger than that in the case of the coolant pump provided with the conventional centrifugal impeller. For the reason, the coolant g in the pump casing 1 below the inducer impeller 2 is positively imparted with a turning force as compared with the conventional coolant pump. This will be described in more detail. Based on the first reason, the coolant fluid g on the lower side of the inducer impeller 2 enters the inlet portion f1 of the helical blade 12 of the inducer impeller 2 rotated by the drive unit 4. A collision force is applied upon collision. Further, based on the second reason, the coolant liquid g boosted by the helical blade 12 leaks downward in a larger amount than in the case of the conventional coolant pump through the radial gap c3, and this leak causes the inducer impeller 2 to flow downward. The coolant liquid g in the pump casing 1 below is given a turning force. The coolant liquid g swirling in the pump casing 1 in this manner imparts energy for swirling to the coolant liquid g outside the pump casing 1 through the suction port 10b, and eventually the coolant liquid g in the coolant liquid tank 14 is given. The whole is turned. Note that the coolant pump 100 promotes the turning of the entire coolant liquid g in the coolant liquid tank 14, and therefore, the lower side of the inducer impeller 2 is opened to the coolant liquid tank 14, and the turn is like a turning prevention plate. Anything that inhibits is not added.

Such swirling of the coolant liquid g causes foreign matter such as chips having a particle size of 2 mm or less mixed in the coolant liquid g to float and flow in the coolant liquid g and together with the coolant liquid g in the suction port 10b of the pump casing 1. To flow. Accordingly, it is possible to suppress foreign matters such as chips from being deposited on the bottom surface in the coolant liquid tank 14 and to save the trouble of cleaning.

<< First Process for Increasing the Total Lift of the Coolant Pump 100 according to the Present Example >>
When a conventional inducer impeller is rotated at 3500 rpm or less, a lift exceeding a few meters (for example, about 6 m to 20 m) required as a coolant pump used for a general machine tool or the like is required. It is not supposed to be generated. In the coolant pump 100, since the form of the inducer impeller 2 is fixed, the relationship between the flow coefficient φ and the lift coefficient ψ cannot be arbitrarily changed, and this can be applied to various full lift coolant pumps. In order to change it to fit, the exit angle θ2 of each helical blade 12a, 12b, 12c of the inducer impeller 2 must be changed.

The relationship between the exit angle θ2 and the head coefficient ψ when the exit angle θ2 is changed in this way will be described with reference to FIG.
In FIG. 10, the horizontal axis represents the exit angle θ2 (degrees) of the impeller, and the vertical axis represents the lift coefficient ψ. A curve e6 represents the relationship between the exit angle θ2 and the lift coefficient ψ confirmed by a computer simulation or a simple experiment.

As determined from FIG. 10, when the exit angle θ2 increases, the inclination angle of the curve gradually increases when the exit angle θ2 is around 7 degrees, and when the exit angle θ2 exceeds 9 degrees, the exit angle is smaller than this. The inclination angle is larger than the inclination angle of the curve e6 at the angle θ2.

In other words, if the exit angle θ2 of the inducer impeller 2 is set to 9 degrees or more, the lift at the outlet portion f2 of each helical blade 12a, 12b, 12c can be changed relatively greatly, and the outlet When the angle θ2 is increased to, for example, about 30 degrees, the head of the coolant pump 100 of the present embodiment can be greatly increased, and it is possible to cope with a wide range of heads generally required as a coolant pump.

Since the inlet angle θ1 of the inducer impeller 2 from which the data of the curve e6 is acquired is 7 degrees, the outlet angle θ2 is set to an arbitrary size that is 2 degrees or more larger than this when compared with the inlet angle θ1. As a result, the coolant pump 100 generates a head having an arbitrary size in a relatively wide range. In other words, when the exit angle θ2 is set to an arbitrary size that is 2 degrees or more larger than the entrance angle θ1, the specific speed in the reference use state of the inducer impeller 2 is large and small in a relatively wide range. The coolant pump 100 according to the present invention including the inducer impeller 2 can generate a head having an arbitrary size in a relatively wide head range.

Differences between the inducer impeller 2 (the former) according to the present embodiment and the conventional inducer impeller 2 (the latter) formed as described above are as follows.
a: The former generates the entire head of the pump 100, whereas the latter is additionally provided on the liquid suction side in order to prevent cavitation of another impeller that forms the main body.
b: The former has an exit angle θ2 of 2 degrees or more, while the latter is smaller than this.
c: In the former case, the specific speed in the reference use state may be about 250 at the minimum, while in the latter, the specific speed in the reference use state is at least about 800.
d: The former may be used at 3500 rpm or less, while the latter is generally used at 7000 rpm or more.

The coolant pump 100 of the present embodiment having the former inducer impeller 2 having such a difference is not limited to simply using the conventional inducer impeller 2 for a new application, and has a structure different from the conventional one. And the inducer impeller 2 which has a concept is provided, and is excellent in practicality.

<< Second treatment for increasing the total head of the coolant pump 100 according to this embodiment >>
In the coolant pump 100 of the present embodiment, during operation, the coolant liquid g leaks from the radial gap c3 between the inducer impeller 2 and the peripheral wall surface of the inner space c0 of the pump casing 1, and this leakage occurs. It has already been explained that the coolant liquid g contributes to turning the coolant liquid g in the pump casing 1 below the inducer impeller 2 and the coolant liquid g in the coolant liquid tank 14. The coolant liquid g acting acts to raise the lift of the coolant pump 100 that sucks the coolant liquid g.

Therefore, by changing the diameter of the inducer impeller 2 without changing the shape of the pump casing 1, the clearance c3 on the radius between the inducer impeller 2 and the inner peripheral wall surface of the inner space c0 of the pump casing 1 is changed. The relationship between the clearance c3, the amount of leakage from the clearance c3, and the lift coefficient of the coolant pump 100 in the case of the above will be described with reference to FIG.

In FIG. 11, the horizontal axis represents the size of the gap c3 (mm) on the radius, and the vertical axis represents the leakage amount (m ³ ) and the head coefficient ψ. A curve e7 represents the relationship between the clearance c3 and the lift coefficient ψ confirmed by a computer simulation or a simple experiment, and its shape approximates a sine curve. When acquiring the data of the curve e7, when the clearance c3 on the radius is 1.5 mm, the head of the coolant pump 100 is 6.4 m and the flow rate of the coolant liquid g is 0.2 m ³ / min.

As judged from FIG. 11, when the radial gap c3 increases, the size of the radial gap c3 is 1.3 mm (1% when expressed as a ratio to the outer diameter of the inducer impeller 2). In the vicinity of the size), the inclination angle of the curve e7 representing the relationship between the leakage amount and the lift coefficient of the coolant pump 100 is small, and then gradually increases. When the radial gap c3 exceeds a certain size, the inclination gradually increases thereafter. A pole k1 that becomes smaller and becomes smaller again in the vicinity of a radius c3 of 4.3 mm (3.3% when expressed as a ratio to the outer diameter of the inducer impeller 2), and eventually reverses positive and negative poles k1. (The point where the size of the gap c3 on the radius is about 4.8 mm) is reached, and thereafter, it becomes a negative value and changes so that its absolute value gradually increases.

Therefore, the clearance c3 on the radius is set to a size within a range in which the size of the clearance c3 and the flow rate leaking to the suction port 10b side of the pump casing 1 through the clearance c3 increases in proportion. Rather than setting a range larger than the gap corresponding to the pole, it is effective in effectively or efficiently increasing the total lift of the coolant pump 100 by the coolant liquid g leaking from the gap c3. Expressed as a percentage of the radius of the inducer impeller 2, it is 1% or more. The ratio is more preferably a numerical value of the gap c3 in the range where the inclination angle of the curve e8 is large, and a range of 2% to 5%.

When the lift of the coolant pump 100 due to the coolant liquid g leaking from the gap c3 is represented by a lift coefficient ψ, it is about 0.15 at the maximum as judged from FIG. 6, and the magnitude is particularly small. Sometimes it exceeds about 50% of the total lift of the coolant pump 100 in the standard use state, and its effectiveness is understood.

Generally, the clearance c3 on the radius between the pump casing 1 and the inducer impeller 2 is set so that the fluid does not leak as much as possible. It is about 5% or less.
Accordingly, the radial gap c3 according to the present embodiment is clear in the reason and size of existence compared to the gap between the conventional impeller and the pump casing in which the fluid in the pump casing 1 is considered not to leak as much as possible. Are distinguished.

<< Characteristic Configuration and Action of Coolant Pump 100 According to the Present Example >>
Next, a supplementary description will be given of the characteristic configuration of the coolant pump 100 according to the present embodiment.
(1) Although the inducer impeller 2 is configured to rotate at 2900 rpm to 3500 rpm, the configuration uses an electric motor that is a drive unit 4 for rotating the inducer impeller 2 for general use. Contributes to getting things done. Thereby, the manufacturing cost of the coolant pump 100 is reduced.
Here, the rotational speed of 2900 rpm is the rotational speed of the two-pole electric motor 4 driven by a commercial power source having a frequency of 50 cycles, and the rotational speed of 3500 rpm is a two-pole motor driven by a commercial power source having a frequency of 60 cycles. This is the rotational speed of the electric motor 4. These rotational speeds are expected to slip with the rotation of the output shaft of the electric motor.

(2) The specific speed Ns (m ³ , min, m) in the standard use state is set in the range of 250 to 650, and the rotational speed of the inducer impeller 2 is set to 2900 rpm to 3500 rpm. When the specific speed Ns is 250, the head of the coolant pump 100 is about 20 m, for example, and the flow rate is about 150 liters / min. On the other hand, when the specific speed Ns is 650, the head of the coolant pump 100 is, for example, about 10 m, and the flow rate thereof is, for example, about 500 liters / min. Thereby, the coolant pump 100 of the present embodiment can obtain various lifts and flow rates that are actually required.

(3) The pump casing 1 is formed with a coolant liquid outlet 5b in the upper part, the lower end is a suction port 10b for the coolant liquid g, its own center lines a1 and a2 are vertically oriented, and the outer diameter is larger than the outer diameter of the inducer impeller. And an inducer impeller 2 is concentrically disposed in a lower range than the coolant outlet 5b in the internal space c0 of the pump casing 1. The inlet part f1 is positioned on the lower side and the outlet part f2 is positioned on the upper side. The pump casing 1 having such a configuration can be formed at low cost by utilizing existing members such as a straight pipe steel pipe and a flange. Further, the pump casing 1 and the inducer impeller 2 efficiently apply a turning force to the coolant liquid g in the coolant liquid tank 14 through the suction port 10b, and useless the kinetic energy of the coolant liquid g in the turning state. It will be sucked up without disappearing.

(4) The drive unit 4 rotates the inducer impeller 2 via the rotation shaft 3 disposed at the center position of the upper range of the inducer impeller 2 in the internal space c0 of the pump casing 1. According to this configuration, the rotating shaft 3 is surrounded by the pump casing 1 and does not come into contact with other objects, and the rotating shaft 3 in the upper portion of the inducer impeller 2 in the internal space c0 is excluded. The cylindrical region is used as an outflow path for the coolant liquid g sent out by the inducer impeller 2, and can suppress the accumulation of foreign matters such as chips contained in the coolant liquid g as compared with the conventional coolant pump. .

(5) The entire range from the lower end of the inducer impeller 2 to the suction port 10b in the internal space c0 of the pump casing 1 is straight and is a complete void with a larger outer diameter than the inducer impeller. According to this configuration, the inducer impeller 2 can efficiently apply the turning force to the coolant liquid g in the coolant liquid tank 14 without being obstructed by an obstacle, and the coolant liquid g in the turning state can be supplied. The kinetic energy can be sucked up without being lost.

(6) Of the range from the upper end of the inducer impeller 2 to the coolant outlet 5b in the internal space c0 of the pump casing 1, the region excluding the rotating shaft 3 is a void or is restricted to swivel in the void. In this configuration, the plate 19 is fixed. According to this, the coolant liquid g sent out by the inducer impeller 2 flows to the coolant liquid outlet 5b. When the turning restricting plate 19 is provided, the turning of the coolant liquid g sent out by the inducer impeller 2 is restricted by the turning restricting plate 19 to convert the turning energy into pressure, and the coolant liquid g flowing out from the coolant liquid outlet 5b. Increase the pressure.

(7) The vertical length of the range from the upper end of the inducer impeller 2 to the coolant outlet 5b in the internal space c0 of the pump casing 1 is set to about 2 to 3 times the outer diameter of the inducer impeller 2. Yes. Thereby, even if there is no turning restricting plate 19 within the range from the upper end of the inducer impeller 2 to the coolant outlet 5b in the internal space c0 of the pump casing 1, the coolant sent out by the inducer impeller 2 is supplied. The swirling of the liquid g is suppressed by friction with the inner surface of the pump casing 1 or viscosity resistance of the coolant liquid.

DESCRIPTION OF SYMBOLS 100 Coolant pump 1 Pump casing 2 Inducer impeller 3 Rotating shaft 4 Drive part 5b Coolant liquid outlet 11 Boss part 10b Suction inlet 12a Helical blade 12b Helical blade 12c Helical blade Ns Specific speed θ2 Outlet angle θ1 Inlet angle a1 Center line a2 Center Line c0 Internal space c3 Clearance d2 Outer diameter f1 of helical blade 12 Inlet part f2 Outlet part g Coolant liquid

Claims (3)

A coolant pump that sucks up coolant liquid, a pump casing having a cylindrical inner space in which a coolant liquid outlet is formed at the top and a coolant liquid suction port is formed at the bottom;
A single inducer impeller for generating the full head of the pump in the pump casing, the inducer impeller is fixed with a plurality of helical blades on the outer periphery of the boss portion;
And for each helical wing, the exit angle is set at least 2 degrees larger than the entrance angle ,
And the radial clearance between the inducer impeller and the inner peripheral wall surface of the pump casing is set to 1% or more of the outer diameter of the inducer impeller part,
A coolant pump, wherein a radial clearance between the inducer impeller and an inner peripheral wall surface of the pump casing is set to 5% or less of an outer diameter of the inducer impeller portion .
The entire range from the lower end of the inducer impeller to the suction port in the internal space is a void having a diameter larger than the outer diameter of the inducer impeller. Coolant pump.
2. The coolant pump according to claim 1, wherein a turning restricting plate is disposed along a vertical direction in a range from an upper end of the inducer impeller to the liquid outlet in the internal space.