Floating Cup Pump (Part 1) — Get to Know

Previously on iHydrostatics N15~17, PCV (Pre-Compression Volume) technology and its applications in real products have been discussed a lot. iEditor is pretty sure you have learned the whole picture of this technique about its pros and cons. If you are interested in this topic, please reply N15/N16/N17 in Wechat iHydrostatics to get the previous posts. Any questions are always welcomed, iEditor encourages you to leave your comments in iHydrostatics QQ Group: 426372753.

Say “See you” to pump noise, say “Hi” to Floating Cup (FC) pump. About piston pump, we are all very familiar with slipper type and bent axis type, but engineers never stop their footsteps. An innovative concept has been come up for piston pump – Floating Cup type. What is floating cup piston pump? How does it look like? What is the difference with the other two types? Take a deep breath, let’s start our journey.

1Difference ComparisonFor piston pump family, slipper type and bent axis type have prevailed in hydraulic industries for a long time. While this family will have a new brother – floating cup type piston pump. In order to know this new brother better, iEditor will compare this new pump with the two tranditional ones.
– Similarity
■ Foremost, bent axis, slipper type and floating cup types all belong to piston pump family. The principle of the three is to utilize changeable piston chamber to suck and discharge oil into system.

■ The three types all use valve plate to commutate oil between inlet and outlet.

– Difference
■ Normally bent axis pump has 7 pistons, slipper type is 9, while floating cup type is 24 pistons with 12 each side.

■ For the barrel in the kit, normally 1 for bent axis and slipper type, while 2 for floating cup.

■ For the max. tilting angle, normally bent axis is 40 degree, slipper type is 20 degree, while floating cup is much samller – 8 degree for each side

■ For the piston chamber sealing, bent axis adopts ring design, slipper type utilizes liner surface concept, floating cup applies ball shaped piston head.

■ Bent axis and slipper type cylinder chamber are all fixed, it’s directly drilled in cylinder block. Floating cup cylinder is not fixed, it can float on barrel. This is why it’s named “Floating Cup”.

■ The three type pump piston have different kinematic principles.
For floating cup pump, the piston is fixed in the rotator with thread, and the cylinder cup not only rotates with the barrel, but also floats on the barrel. So in this way, there is no high normal contact force between piston and cylinder cup.




2What’s New of Floating CupBent axis type and slipper type both have its own pros and cons. Floating cup, this new innovative concept has combined the advantages from the two. Because of this new design, floating cup has structured its own characteristics.
Floating Cylinder Cup. The reason of calling it “Floating” is that cylinder cup is not fixed on the barrel plate, it can move a little bit to adapt elliptic trace. Meanwhile, pressure reaction on the bottom of cup allows the cup to float.

Fixed Piston. Either bent axis type or slipper type, the piston can move within its constraints, while for floating cup, the piston is fixed in the rotor with thread or press fit.

Ball-Shaped Seal. Unlike to bent axis type with ring seal or slipper type with surface seal, floating cup piston is with a ball-shaped head, this will allow the line seal and the sealing line is always perpendicular to cup bore no matter of the barrel angle.

Mirrored Barrel Design. In the floating cup design, the bearing load is minimized by the mirrored design having two rings of pistons. In the axial direction each ring is hydrostatically balanced by the other. In this way, balanced force can be achieved.


3Floating Cup MoreFloating cup principle, this totally new concept for pump and motor has more secrets to be discovered, we just started this journey. iEditor has high interest in this innovative product with new idea and plan to share it step by step. If you are interested in this as well, please follow iHydrostatics closely.
In the next post, we will together to investigate the detailed design of each part and how this pump is assembled.

REFERENCES

[1]. Floating Cup Intro 2007. INNAS.
[2]. Floating Cup Brochure. INNAS.
[3]. DESIGN AND TESTING OF AN AXIAL PISTON PUMP BASED ON THE FLOATING CUP PRINCIPLE. Dr.ir.Peter Achten. SICFP’03.

STATEMENTS

[1]. Copyright of the pictures, videos and paragraphs quoted in this post belong to the original author.
[2]. iHydrostatics is only the platform to share but not create information, iHydrostatics post is NOT intended for academic research.
[3]. This post reprint should be noted with “iHydrostatics Original”.