Outline of Trochoid® pump

Torochoid Pump is an internal gear pump that rotates meshing an outer rotor (internal gear)
and an inner rotor (external gear) which is accommodated in the outer rotor. The rotor tooth is
formed in a shape of trochoid curve. Therefore the pump is named “Trochoid Pump” and is a
registered trademark of Nippon oil pump co.,Ltd.
Trochoid Pump comprises an inner and an outer rotor, a shaft, a shaft bearing and casing with a
round hole which accommodates the rotors.
The shaft is located in the center of the inner rotor and the outer and inner rotor are assembled
eccentrically so when inner rotor rotates, the outer rotor also rotates in the same direction with
a little delay.
Since the number of teeth of the inner rotor is one lesser than that of the outer rotor, the volume of the gap between the inner and the outer rotors changes continuously depending on
the position. So any given volume first increases, and then decreases. An increase creates a
vacuum. This vacuum creates suction, As a volume decreases compression occurs. During this
compression period, fluids can be pumped.

Trochoid Pump is an internal gear pump and the discharge rate is fixed.
However, the relationship between the discharge and pressure changes in a straight line when
the rotational speed is constant, and the flow rate becomes maximum when there is no pressure.
The required power is linearly proportional to the pressure and hence, at the maximum pressure the motor output is maximum. Therefore, please note that operating against closed discharge may damage the pump or overload the motor.

3 Factors to determine the performance of Trochoid® pump

1. Trochoid® pumphead has two following spaces to fix its performance.
   Space 1: Gap between the gears of both rotors when they mesh.
   Space 2: Gap between both rotors and room of casing rotor.
2. Oil temperature
   Above gaps are out of allowance if the temperature of pumphead is abnormally hot or cold then pump becomes hard to rotate, suck or discharge, so use under proper temperature.
3. Contamination
   If contamination which is larger than the gap between inside rotors comes in pumphead directly, or contamination with high viscosity oil comes in there, gear/rotor might be damaged by these then it is hard to achieve its performance.

See and check with NOP Trochoid product guide on this website.

See and check with NOP Trochoid® pump product guide on this website.

Trochoid® pump is able to transport oil, but some models enable to transport coolant fluid for machine tool, fuel oil ,medical-use fluid. Water can be transferred by PROCON® pump.

*Gasoline and volatile oil can NOT be transferred by NOP pump.

See details here

The allowable range of fluid temperature for regular Trochoid® pump is from -5℃ to 80℃.

NOP® gives the special model for below condition:

For high temperature use (-5 to 120℃)
For super-high temperature use (-5 to 200℃)

Notice for above special model: temperature gap between inside pump and fluid must be within 40℃.

Allowable viscosity range for Trochoid® pump is from 10 to 500cSt. When using in high viscosity fluid, resistance in suction pipe must be as small as possible (less than -0.03MPa is desiable). If high viscosity fluid is transported, required torque to operate pump properly must be larger so be careful to choose the type of motor.
If low viscosity fluid is transported, amount of leaking oil must be larger, then efficiency of transpotation is lower so that it may be hard to achieve max. pressure shown in product catalog/spec sheet.

See below link:
Trochoid® pump specification(Japanese)

The permissible rotational speed range of the Trochoid Pump is 500 to 1,800rpm. The minimum rotation speed varies depending on the pump type and specifications, but the flow rate is
proportional to the rotation speed up to 300rpm.
In addition, the suction capacity will decrease as rotation speed slows down, so please make
sure that the suction head is below 50 to 100cm. (It also depends on pump types and other
conditions).

Allowablle max. capacity to resist pressure in Trochoid® pump is 150% large as discharge max. pressure of the pump. But allowable max. pressure in oil seal is 0.03MPa.

When the operation of pump stops, do NOT load more than 0.03MPa pressure at the pump and even when pump runs, do not load more than 0.03MPa positive pressure at the suction port.

NOP® has 4 types of special spec model. they have specific charactor on the model name to distinguish from regular model.

Specific charactor for special spec model:
US (Low tenperature spec) 　　　
VF (High temperature spec)
UT (Anti-chemical fluid spec)
VH (Super high temperature spec)

Details of specification is illustrated in below link, and consult NOP customer support
Special spec code

The directions of rotation/suction and discharge port of Trochoid® pump is fixed except for the reversible pumps (NOP RA series). Therefore, to avoid misuse and trouble, check the instruction printed on the nameplate in the pump carefully before the installation.
The direction of rotation (clockwise or anti-clockwise) and the location of suction and discharge port differ depending on the pump type/model, so check it on product guide/instruction manual.

Trochoid® pump 2HB is the successor of 2HA series. (2HA has already been discontinued)
Overall dimention is same between them, the only difference is the type of suction/discharge port. (HB: PT type, HA:PF type)

Details of 2HB is shown in below:

Trochoid pump/model list (Japanese)

Before operating coolant pump, check the condition of coolant fluid and set up countermesure to remove chips and sludges ahead of the suction port of Trochoid® pump.
At least, place the separate plate in the coolant tank.
In suction part of pump, set up the suction filter (more than 60mesh filter) ahead of the Trochoid® pump.

1. NOP® Coolant Trochoid® pump is designed to transfer coolant fluid only, and to enhance the durability, most suitable materials with heat treatment and special-made bearing are used.
2. Compared with conventional impeller pump, NOP® Coolant pump 2HWM type achieves much higer pressure (max. 2.0MPa) so that it enables to cool down the workpiece and blow up contamination more effectively in machine tool.
3. 2HWM is self-priming pump and it is not neccessary to set up any preparation before operating starts.
4. If you use 2HBM type, you can replace it with 2HWM easily because of same installation dimention between them.

   ※Detailed specs are shown in below:
   Trochoid® pump model list (Japanese)

Water-soluble coolant (soluble, solution, emulsion type) , water-insoluble coolant can be used for coolant trochoid® pump.
Fluid temperature must be under 60℃ when coolant pump wortks. Do not use pure water.

1. MICROTOP is a kind of portable filtration pump.
2. It comes with power cable, switch and plastic hoses for discharg and suction.
3. This pump has a filter in discharging line and possible to see the amount of chip/sludge by pressure gauge. To protect motor, pump and filter, MICROTOP has built-in relief valve.
   *Two types of filter for MICROTOP are available. (3μm/10μm)
4. Basic specification
   Discharge rate : 12L/min (50Hz), 14.4L/min(60Hz) 　
   Discharge pressure: 0.3MPa 　　
   Spec of motor：Single phase 100/200V 400W/4P 　　
   Weight: 15kg
5. Basic structure and detailed specs are shown in this PDF.

This pump consists of lunary gears and these contact in one point continuously. Lunary pump enables to trace ideal closed curve by the combination of straight/oval locus so that this pump realizes high durability and few loss by slipping of each gear.

● Advantages:
1: Less pulsation, low noise.
2: No cavitation → Suitable for high viscosity oil
3: High durability due to the usage of low-slip gear.
Loaded torque for input axis is relatively small → Possible to operate economically

● Basic Specifications
Theoritical discarge capacity: 150-250cm³/rev (depends on model) 　
Max. allowable pressure: 1MPa (depends on model) 　
Max. rotation speed：1,800rpm 　
Range of kinematic viscosity: 56-2,000mm²/sec

●Details are shown in below site:
Trochoid® pump type list (Japanese)

1. Clean Hat series are pumps with built-in suction filter, and it sucks dirty oil from intake port on the sub-plate of pumphead and only clean oil is able to pass through sunction filter then goes into pumphead and rotor and it is discharged from outlet port, so that chips/sludges do not hurt gear and other parts in pumphead.
2. Due to built-in filter, it is not nessesary to plumb the pipe for filter, and Clean hat series have two types, the one is cartridge filter type and the last one is washable element filter type.
3. This pump comes with valuum gauge which can delect the timing to replace/wash the filter,
4. Basic structure and details is shown here PDF.

Following chart illustrates a variation of filter for Clean Hat.
There is 3 types of filter (60mesh, 100mesh, 150mesh) and possible to order by below model name.

Flow rate vs Viscosity vs loss of pressure on element for 2HB(W)PVBE is shown here: PDF
How to relace filter is shown here: PDF

1. Choose intake pipe with this spec of flow velocity: less than 1.5m/sec.
   (Diameter of pipe must be equal or more than diameter of intake port of pump)
2. Suction head must be calculated from the lowest point of fluid level.
3. Intake piping layout must NOT be affected by returned oil from relief valve and actuater.
4. Length of intake pipe must be as short as possible, and number of vending point must be as less as possible.
5. Cock, valve, joint must be checked carefully and do not use parts whose port is very narrow and which has blow-hole or cavity.
6. Cross section of all inlet/outlet pipe must be same.

Diameter of pipe must be fixed in the consideration of resistance of pipe after estimating passing pressure and flow velosity. In the case of low/hiigh pressure type of Trochoid® pump, preferred flow velosity inside the pipe is less than 3m/sec.

Value of back pressure must NOT be too much in designing of returning pipe layout, and flow velosity must be as low as possible if water-hammer is expected when switching to other valve.
Generally, desiable flow velosity is the range from 1.5 to 4.0m/sec.
The end of returing pipe must be placed under surface line of oil, and keep distance from the end of suction pipe. Separate plate must be placed between discharge pipe and returing pipe.

When placing 2VD (Relief valve) placed on Trochoid® pump 2HB/2HWM, the diameter of connecting pipe must be Rc 3/8 or larger than it.

1. Below shows the required torque to tighten screw.
   *If tightening it with more than required torque, pump unit may be damaged.

   Rc1/8 →10N・m
   Rc1/4 →20N・m
   Rc3/8 →20N・m
   Rc1/2 →25N・m
   Rc3/4 →30N・m
   Rc1 →70N・m
   Rc11/4 →80N・m
   Rc11/2 →90N・m

2. Connect pump and each pipe securely to prevent from air-leaking.
3. Place props to support pipes to prevent from weight loaded by pipe itself.
4. Clean up inside of pipes to prevent from trouble with pump and related devices.

It is necessary to protect pump unit.
The capacity of suction filter must be two times larger than the capacity of pump itself, mesh filter is recommended to be 60 to 150 mesh.

Trochoid® pump is designed under the condition that no radial load, and no thrust load is on the pump shaft. Amount of Eccentricity between motor drive shaft and pump shaft must be within TIR 0.05.

The location of Trochoid® pump must be lower than the level of drive motor.

Protector must be placed for the safety reason.

It is banned to mount pump at too dusty, too hot, too cold place/area. Consult NOP customer service/NOP distributors if you aim to use the pump outside building.

1. Relief valve of Trochoid® pump is direct acting type and relief pressure is regulated by metal spring. Actual pressure is set/adjusted by pressure regulating screw. Spring rate differs, depending on value of the pressure which customer designates.
2. NOP® relief valve works as safety valve to release over-loaded pressure, and pressure regulator, and two types of relief valve are availabe, the one is internal return type and the other is external return type.
3. If choosing internal return relief valve as safety valve, never operate more than 30 seconds under the condition that pump drives and discharge port is closed, otherwise pump and motor may burn.
4. If choosing internal return relief valve as pressure regulator, never set up it under the condition that the amont of released oil is more than 50% of total discharged oil, otherwise pump may burn.
5. If choosing external relief valve, it is doable to use it as safety valve and pressure regulator and released oil must be returned into oil tank.
6. Details of relief valve is illustrated in this PDF (Japanese).

Cracking pressure is the point to start opening relief valve and flowing liquid.

Reseat pressure is the point that the pressure at the suction port in relief valve goes down and amount of released oil is reduced to fixed point.

Override pressure is the difference between cracking pressure and the pressure when relief valve is fully opened. The smaller its difference is, the better relief performance is.

1. Confirm the direction of rotation, inlet/outlet port of fluid.
2. Confirm fluid is fully filled up to the inlet line, and oil itself is clean.
3. Confirm each piping is fully fixed.
4. Confirm inlet/outlet valves are fully opened.

Check below points when you start opearating NOP pump.

・Oil lealing from connecting point and oil seal

・Strange noise

・Abnormal heat-up on pump body

1. How to connect wire to the motor is illusrated in the terminal box in the motor.
2. For Trochoid® pump with built-in motor, refer to this PDF.

Refer to below. (from the view of drive shaft)
TOP-1ME: Anticlockwise
TOP-2MY: Anticlockwise
TOP-2ME: Anticlockwise
TOP-3MF: Clockwise

Do NOT operate Trochoid® pump with no fluid flowing more than 10 seconds. If you see the symptom that pump doesn't suck any fluid, stop operation of pump immediately then inspect its cause and take countermeasures.

Seal kit/bearing is available to order, check details on below:
Sealkit_bearing_pdf

Contact to NOP customer service if other parts are needed.

As far as pump is used as critical parts in the system, inspect it annually at least if pump runs properly. If some damage is detected, replace oil seal, gasket, bearing with new one.

Cavitation is an issue in fluid flow system. As suction pipe is narrow or resistance of filter, valve in suction line is large, bubbles come up in fluid flow then discharge pressure makes bubbles compressed then impact force occurs and below symptoms happen.

1. Decrease of the volume of discharging fluid
2. Large noise
3. Vivration
4. Corrosion
5. Air in discharged oil

Cause of cavitation: viscosity is too high or suction head power is too large.

Check it in product catalog/guide of Trochoid® pump at NOP website.

1. Air comes from the joint in suction line. 　　
   Check the connecting point and fix or start over the flow line if necessary.
2. Air comes from oil seal. 　　
   Replace oil seal.
3. Lack of the fluid
   Refill fluid up to regulated amount.
4. Air comes into return pipe line
   Position of the port of return pipe must be lower than fluid surface, and keep distance from the suction port. Set up the separate plate beween suction port and return port.
5. Cavitation occurs.
   See details in "What is cavitation" in FAQ.

Before disassembling pump, check below 1 to 3:

1. Trouble in centering of coupling　　
   Check if the centering is set up correctly.
   →If no, Re-set the centering rightly. (Follow the regulated value ruled by coupling manufacturer)
2. Abrasion on bearing in motor or pump shaft.
   Check shaft if there is some gap between bearing and shaft. 　
   →If yes, replace bearing.
3. Sympathetic vibration occurs in base of pump and motor.　
   Check base if it absorbs vibration from motor properly.
   →If it is clear that vivration comes from motor, place anti-vivration rubber between motor and base.

Trouble in the suction may occur, check below:

1. Cavitation
   Check if suction pressure is suitable. Its pressure is more than -0.04MPa, reduce resistance in suction line.

   A: Remove dust in strainer, change the size of mesh filter.
   B: Enlarge size of intake pipe, change length of suction pipe, re-design of piping layout.
   C: Change viscocity of fluid

2. Air comes into fluid

   A: Air comes from joint part in suction pipe.
   →Find part where air comes in and tighten screw to fix pipe, or re-set up piping.

   B: Air comes from oil seal→Replace oil seal.

   C: Lack of fluid
   →Refill oil up to regulated amount.

   D: Air comes into return port
   Position of the port of return pipe must be lower than fluid surface, and keep distance from the suction port. Set up the separating plate beween suction port and return port.

Check the actual current value if motor is over-loaded.
as far as detected current value is under rated one and surface of motor is below 60℃, it is no problem to drive.

If current value is more than rated one, reduce discharge pressure or raise output power of motor.