HydraForce Insider Blog

Using a Proportional Pressure Control as a Directional Control Valve

Posted by David Price on Fri, May 13, 2011 @ 10:05 AM

With Programmable Electronic Controls becoming more prevalent in many hydraulic systems it’s a good time to look at one alternative to Proportional Direction control made possible with the advent of electronic closed loop control.

 

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Tags: cartridge valves, proportional valves, Directional Control Valves, proportional pressure control valve, solenoid operated four way valves, directional control valve, hydraulic manifold design, ecu's, hydraulic circuit

Combining Cartridge Valves to Create a Versatile Flow Divider

Posted by David Price on Thu, Mar 17, 2011 @ 14:03 PM

Are you looking for an alternative for your Flow Divider circuit that will address the issues of multiple division, irregular percentage splits, adjustable ratios, inlet flow variance versus accuracy and pressure drop?  If so, an alternative works for dividing pump flow only.  If you need combining too, you might have to stick with the traditional flow divider / combiner (or read next week’s article to see a combining solution). 

Flow dividing circuits are used in many mobile applications to make full use of a varying input flow.  Spool type dividers can be integrated into manifolds and are available in many sizes and fixed ratios.  Although they can be cascaded, they are individually limited to a 2-way split.  The valve ratios (i.e. 50/50 or 20/80) are fixed and factory preset by varying each spools flow specifications.

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Tags: cartridge valves, proportional valves, Load Sensing, Cartridge Valve Pressure Compensators, benefits of cartridge valves, Flow Divider, hydraulic manifold design, pressure compensators

Leveraging Proportional Valve Technology

Posted by David Price on Thu, Mar 10, 2011 @ 10:03 AM

Are You Ready to Move from On/Off to Proportional Control but your Customers Aren't?

This is an ongoing battle for most of us. There is some pretty slick new technology out there that will make most equipment more efficient, safer, lighter, smaller, and even greener, but getting the end users and industries to adapt is quite another issue.

One of the simplest moves in this area from a valve standpoint is moving from bang/bang or On/Off control to proportional control. I use the word “simplest” quite loosely here, so let me explain.

There are still lots of industries out there where Manual Levers are KING and getting operators to move to joysticks, control panels, buttons and knobs is an uphill battle. I am not sure we will ever get away from the manual levers, but for those of you whose equipment is already electro-hydraulic, moving from on/off to proportional can be quite simple.

When looking at creating custom mono-blocks or custom manifolds, we all know that quantity plays a role in the cost-effectiveness of this option. So, if you needed one manifold for on/off and one for proportional, going the custom, mono-block option is probably not feasible. For example, if the majority of your machines use on/off, while only a few select customers see the advantages of proportional, designing the machine to accommodate two different custom manifolds is just not practical. But what if you could design one custom manifold block that can be either on/off or proportional by switching out the on/off valves with the equivalent proportional valves? In other words, you could use the same manifold block for 100% of your applications even though some of those applications are on/off and some are proportional. I will review an example and discuss a little about the cost implications, but for the most part, you will see that this option is very feasible.

Let’s take a sweeper application. In most cases on/off control of the brooms is sufficient and probably an industry standard, so most operators are used to it and therefore prefer it. However, having proportional broom control offers clear advantages, such as: slowing down the brooms for certain surfaces which could extend broom life, as well as having the option of controlling broom speeds for specific debris, which would improve productivity. A very cost-effective solution can be created by designing a custom manifold that uses on/off valves for the majority of users, but has the proportional option for the progressive users just by swapping out a cartridge. (Electrical scheme notwithstanding but I will discuss this later.) So, as the sweeper OEMs push to move their customers and industry to proportional, the packaging of the hydraulic valve system doesn’t have to change, keeping overall cost to a minimum.

Below is a simplified version of the on/off circuit and the proportional circuit. The trick is that the port logic and cavity details must be exactly the same for both the on/off and the proportional valve. In this example, both valves use the VC12-3 cavity and both have the same port logic of open from port 1 to port 3 with port 2 blocked in the normal condition. And when energized, port 1 opens to port 2 blocking port 3 for the on/off, and proportioning flow from port 1 to port 2 while bypassing what isn’t needed to port 3. In this case, the valve hardware change is roughly $55.00 list per valve.

Dual Coil Polarity Issues Figs. 1, 2, 3


The advantage is that the end users can upgrade their equipment with a field kit from the OEM. As the industry moves toward proportional, and the mix of machines starts to change to more proportional than on/off, the OEM doesn’t have to create a new manifold. The manifold can be preconfigured so that it has commonality of parts, which means lower development cost and service costs, usage of the custom component (manifold in this case) remains consistent, longer machine production life, and so on.

To help you look at this as an option for your equipment development, here is a list of HydraForce on/off valves and their equivalent proportional valve partners having the same cavity detail and port logic:

On/Off Valves
Solenoid Operated
Proportional Valves
Solenoid Operated
SVxx-20
SPxx-20
SVxx-21 SPxx-21
SVxx-22 SPxx-22
SVxx-25 SPxx-25
SVCLxx-30 SPCLxx-30
SVCLxx-31 SPCLxx-32
SVxx-46R SPxx-46R
SVxx-47x SPxx-47x
SVxx-5x SPxx-5x
SV12-33 PV72-31
SV08-33 PV08-31
SV08-31 PV08-30
SVRVxx-26 TSxx-26
SV10-33 TS10-36
Manually Operated  
PR10-36 TS10-36
RV08-20 TS08-20 / TS38-30
RVxx-26 TSxx-26
FRxx-32 ZLxx-30
FRxx-33 PVxx-30
FR12-23 PV72-20 / PV72-21
FR16-20 PV16-23
NV12-30 PV72-33 / PV72-35
MR10-47 SP10-47
MP10-47 SP10-47
Piloted with On/Off Valve or Pressure Reducing/Relieving
SV08-33 EHPR08-33
PDxx-S67 PExx-S67

Some of these conversions are pretty self explanatory, while other might be a bit confusing. Switching the SV08-20 with an SP08-20 is obvious. However, why would you switch from an SV08-33 directional selector to an EHRP08-33 proportional pressure reducing valve? In this case, these two valves would be used in conjunction with a pilot element. In our case the PD16–S67 would be piloted with the SV08-33 selector for the on/off version. If proportional directional control is needed, swapping out the PD with the PE metering element and using the EHPR proportional reducing valve will control pressure against the PE springs, which gives you the proportional movement of the metering spool.

In this case the additional valve hardware cost is less then $100 list.
A great feature for such a small price increase.

Another thing to keep in mind when designing a custom manifold solution for either option: the coils may or may not be identical when going from the on/off to the proportional. (My pricing comments include the coil changes.) In both of my examples, the SV12 spool valve coil was changed to the 70 size coil used on the PV’s and the SV08 coil was changed to an 06 EHPR coil. You can see how planning for adequate spacing of components on the manifold is critical. Check out our free i-Design software for easy manifold customization and configuration flexibility.

Depending on how your machine controllers are configured, a simple “patch’ download for proportional would cost virtually nothing. It’s hard to say where the costing for the electronics would fall. But doing your due diligence in the beginning and planning for this feature will definitely keep the costs down. Adding proportional electronics after the fact will be much more costly. There will, most likely, be some additional costs up front in terms of the controller, the software programming, and the input device, but how will that compare to your readiness when your customers and industry take the leap? Will you be ready?

For more in-depth electronics discussion, contact your local HydraForce expert.

About the Author:

Lisa DeBenedetto is a Regional Manager at HydraForce with more than 20 years of hydraulic experience. She has been with HydraForce for over 16 years. Contact Lisa

 

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Tags: cartridge valves, proportional valves, Directional Control Valves, directional control valve, hydraulic manifold design, HydraForce, solenoid operated five way valves, manifold design, hydraulic cartridge valves, solenoid valves, proportional directional valves

Suggestions for Cost-Effective Hydraulic Manifold Design

Posted by David Price on Thu, Mar 10, 2011 @ 08:03 AM

Great things come in small packages. In the case of an integrated hydraulic circuit, the smaller, the better. Among the many benefits of a made-to-order block is the ability to achieve a smaller size through a more intelligent design. The 3D layout feature in i-Design will help you conceptualize your design in order to achieve a smaller hydraulic integrated circuit.

In this post I will attempt to clarify the common pricing modifiers that will affect the cost of a hydraulic manifold.

If you are not already familiar with HydraForce's manifold design software called i-Design, you can GO HERE to download a copy today , or contact your local HydraForce distributor to request a copy in disc. HydraForce continues to invest in and refine its i-Design software, and the best part of all: it's FREE!  In 2008, as part of our refinement efforts, HydraForce embarked on a comprehensive research project that included our manifold designers, purchasing department, and our manifold suppliers. The objective of this research was to further refine the scheme we use for pricing manifolds in i-Design by factoring-in the less tangible features of a manifold such as the number of cavities on a surface, the number of ports on a surface, and the mix of large and small cavities. We did this research to develop a better pricing model for our custom manifolds, but the results also offer valuable insight for those of you that design and manufacture their own manifold blocks. Each of the following features has an effect on the complexity and ultimately the cost of the manifold block itself. Unlike a copy of i-Design, spindle time and material are not free.  With the release of i-Design 2.0 in 2008, we included pricing rules for the following manifold modifiers:

• Extra port spacing.
• Cavity mix.
• Number of cavities.
• Number of cavities and/or ports on a surface.
• Ratio of large and small valves.

Extra port spacing for ease of installing fittings is self-explanatory, additional material is required. The cavity mix influences the price because a variety of 08 and 12 size cavities, for example, will require additional cross drills to connect the cavities. Depending on the arrangement, the number of valves or ports on a particular surface can also increase the complexity and the size of the manifold, therefore increasing the cost.
 
Some of these cost factors are not triggered until you lock components and ports to particular surfaces. If we receive an i-Design that includes a manifold layout, but the valves and ports are not locked to particular surfaces or locations, then we interpret the layout as simply a suggestion rather than a necessity. If a particular layout is desired, please use the locking feature in i-Design.
 
Another factor that influences the cost of a manifold is being required to conform to an existing mounting pattern. As you can see from the examples below, the additional material and machining will add cost to the manifold block.

Two manifolds
Two functionally equivalent manifolds
with different mounting hole arrangements.

Original Mounting pattern
Manifold design using the original mounting pattern.

Compact Manifold
More compact version of the manifold.

In conclusion, if you have a manifold design that has a specific mounting configuration that must be adhered to, be aware, it may increase the overall cost of the manifold. If HydraForce needs to conform to a mounting configuration, please use the locking feature in the 2D or 3D layout pages. Being flexible with your manifold requirements gives HydraForce and other manifold designers the freedom to provide you with an optimized, efficient, cost-effective design.

If you would like more information about i-Design,
please contact the i-Design Help Desk.

TO DOWNLOAD A FREE COPY OF i-DESIGN V.3, CLICK HERE


About the Author:

Craig Sinnott is a Regional Manager at HydraForce with more than 16 years of hydraulic experience. Contact Craig

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Tags: cartridge valves, hydraulic manifold design, HydraForce, hydraulic integrated circuit, manifold design