HydraForce Insider Blog

Last time we discussed how to make a flow divider with separate cartridges.  If this was of interest the following goes a little deeper into this subject and shows how to maximize the versatility and address general flow divider issues. First off, it’s worth noting that unlike Flow Sharing the pump itself does not have to be load sensed if all flow is to be utilized in a stand-alone circuit. a)

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.

Are you headed to Las Vegas for Conexpo- Con/Agg 2011 - Con/Agg 2011?  As you already know, anyone who is anyone will be at this event!  HydraForce is no exception; we are located at BOOTH S-15729.  After coming home from our most successful show yet, Bauma China, we are ready for IFPE 2011.

We are going back to the basics with our show setup and layout.   Our most successful shows have been when we highlight and focus on what we do best – innovation.  Visit us at Booth S-15729 and we will be happy to show you why we are the industry leader.  

At the 2011 Conexpo- Con/Agg 2011 - Con/Agg 2011 HydraForce will have 5 stations set up highlighting new product developments.  Did you know that even during the poor economy HydraForce continued investing in R & D?  In fact, we spent the same dollar amount on R & D during 2009 and 2010 as we had in 2008, even though we all know the sales were down significantly during these years.  That should speak volumes to our commitment to innovation.

One of the stations will highlight our new CoreTek Controller product line.  Our customers wanted controllers with an open programming interface and plenty of power for driving valves, well now you do.  The CoreTek controller line uses the CoDeSys software platform, making programming simple and in your control with zero annual licensing fees!  Four controllers with varying I/O configurations are available, and as your feedback dictated, the controllers are CE rated to ISO 14982.   

Station 2 will highlight of our new valve innovations.  Maybe you already knew about our technology for combining two hydraulic functions in one cartridge.  At Conexpo- Con/Agg 2011 we’ll be introducing valves with 3 functions in a single cartridge!  At IFPE 2008, we introduced a handful of these cartridges and we have continued the past 3 years to develop more.  These cartridges can reduce the cost of hydraulic integrated circuits, making manifolds smaller and lighter.  Thanks to your help and ideas, these types of valves have really taken off in the market.  So, if you are thinking about updating your machine designs, it’s time to take a look at HydraForce and these revolutionary new cartridges.

We are also pleased to show off our full line of proportional valves.  HydraForce is the largest supplier of proportional valves, and we continue to add products regularly.  The innovation of bringing 2 functions, or some cases, 3 functions into one cartridge has migrated to our proportional line.  The latest valve series is actually pulling double duty at the show.  It is not only a proportional directional valve (which doubles as flow control), but also a double blocking valve with a built in load sense port and reverse flow check.  These new proportional double blocking valves with built in load sense can be used to create some unique and cost effective circuit designs, which, incidentally, will be unveiled at this years show.

I mentioned unique and cost effective circuits using this new valve technology, however I don’t think I want to let this cat out of the bag just yet!  You will just have to come see for yourself. Let’s just say we are pretty sure HydraForce will soon be able to break into the high flow proportional directional sectional stack valve market!  So if haven’t looked at, or thought of HydraForce for your proportional sectional stack valve applications, it’s time you do!

The new green movement is creating a global economy where OEM’s are looking to make their equipment, faster, cheaper, and greener.  More and more we see the development of smaller more compact equipment designed to do the work of older, larger, less green equipment.  In order to get the power needed, system pressures are increasing and things like cylinders and actuators are getting smaller.  HydraForce has seen the need for a reliable, high cycle, high-pressure cartridge valve line, and it is now in full development!  The HyPerformance cartridge valve program that will consist of a full offering of our cartridge valves (we hope it will take the market by storm).  These new HyPerformance valves are continuous duty rated to over 5000 PSI/350 Bar and have 10% duty cycle rating to over 6000 PSI/ 420 Bar.  There are a few patent pending technologies at play here with this new series of valves.  One of these patents pertains to the new solenoid tube design. Yes, even the solenoid tubes are tested and rated to these pressures.  Over 90 valves are released and ready for your high-pressure application, come see this exciting new series of HyPerformance valves.

In addition to all of the new products, we will have an i-Design station where you can learn how to use the tool, and learn more about the various new features of the tool.  i-Design experts will be there to answer your questions and listen to your feedback.  If you’d like to get a head start on using i-Design, you can download the software now by clicking here.  We will also have copies of this free circuit design software on hand.  

Other news and note worthy information is the new and improved E-Coil that will soon be available with the ASTM B117 960 hour salt spray specification.  

Lastly, we have – FINALLY – created a Condensed HydraForce Catalog, one that will not dislocate your shoulder if you try to carry it in your brief case.  Swing by our booth to register for your own copy. 

The IFPE is always a great way to re-connect and see what’s new and old (~me~).  For those of you who know me, I’ve been at everyone one of these since I started here 16 years ago. As usual, I am looking forward to it: seeing some old friends and associates and hopefully meeting some new ones, so swing by and say Hi! 

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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

While there are many uses for L.S. priority valves, typically they are used to provide priority flow and/or pressure to certain components or functions depending on need. One of the most common uses is to apply them with L.S. steering orbitals. The two most common types of L.S. steering orbitals (Static and Dynamic) are shown below. We use a static L.S. priority valve (ECxx-42) with a static steering orbital and a dynamic L.S. priority valve (ECxx-43) with a dynamic steering orbital. Notice the direction of the sense flow.

Static Steering Unit In a static steering system, the sense flow goes from the steering orbital to the EC valve. The faster you turn the steering wheel, the more flow comes out the work ports. There are several variable orifices in the steering orbital, which open and close proportionally based on how fast you spin the wheel. In neutral, the sense pressure vents to tank through the steering unit.		Dynamic Steering Unit In a dynamic steering system, the sense flow goes from the EC valve to the steering orbital and back to tank through the variable bleed orifice in the steering orbital. Turning the steering wheel opens the work ports and closes the bleed-off orifice, thus building pressure in the sense line pushing on the EC spool. This directs more oil to the orbital the faster you spin the wheel.
Most Steering Circuits Utilizing Orbitals Use a Dynamic Setup Since the steering unit is really just a rotary style variable orifice, using a pre-compensator in conjunction with it makes the steering function compensated. With a given steering RPM, the flow will remain constant regardless of varying load pressure. The boost orifice needs to be located in the shown position to prevent slow movement of the EC spool when the RV opens, thus preventing a pressure spike. The objective is for the steering to work perfectly with as little pressure drop as possible, however sometimes we need to fine tune the responsiveness or the maximun steering flow by tweaking a few things.
Ways to Fine-Tune the Circuit to Optimize Steering Performance The pressure differential between the EC valve and the L.S. port of the steering unit is called the margin pressure. This pressure differential controls the responsiveness and the maximum steering flow. This is determined by a combination of the bias spring of the EC and boost orifice. The dynamic L.S. priority valves have two orifices in the spool, one for damping (PP), and the other for feeding (DS) oil to the orbital. The pilot flow to the L.S. port of the steering unit is determined by the spring value and the feed orifice. The spring value is typically either 80 psi or 100 psi, while the orifice is typically between 0.020" and 0.031" Dia., depending on which size EC valve you are using. You can create any margin pressure you want by simply increasing or decreasing the size of the boost orifice. The smaller the orifice, the higher the margin pressure. Pressure drop data from a steering unit catalog will help determine what is required to achieve the flow you need. However, the responsiveness or optimum feel is typically determined by an expert operator. By increasing or decreasing the boost orifice, you will be able to fine-tune the responsiveness or feel of the steering wheel. An increase or decrease of as little as 0.002" Dia. can make a huge difference in the steering feel. Margin pressure that is too low will result in steering that is slow and sluggish. Margin pressure too high will result in jerky steering.
There are many other uses for L.S. Priority Valves as shown below:
Proportional Steering and On/Off Lift Circuit It is common to use proportional valves instead of steering orbitals to steer many types of equipment. This circuit simply gives priority to steering while allowing the excess flow to lift and lower a cylinder. The EC valve not only gives priority to steering, it also compensates the proportional valve so the same current value will achieve the same flow regardless of load.
Priority Valve Working with Manual Valve It is becoming more common to use an EC valve mounted to the inlet of a manual valve to give priority to certain functions while also limiting the maximum flow and pressure to those functions.
Typical Priority-on-Demand Flow Control Circuit Most uses of the L.S. Priority Valves are for flow control. By sensing downstream of a fixed or variable orifice, you can compensate the circuit. The needle valve shown above could be any one of a number of components such as a ball valve, proportional valve, on/off valve or a simple orifice.		Pressure Control Valve Many people don't realize you can use an ECxx-42 or ECxx-43 to create a pressure control. Think of this as a pressure reducing valve with an excess flow port. The valve will modulate to maintain the spring value in the priority (CF) leg regardless of flow and/or the downstream pressure and flow in the bypass leg. Higher spring pressures can be achieved by using an ECxx-43 and boosting the sense line with an orifice or relief valve.

Do you have another Priority Valve Application?
Do you have any questions about any of the circuits I describe here?
Shoot me an email if you’d like to share your application or ask a question.

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About the Author:

Scott Parker is a Senior Application Engineer at HydraForce.
He’s been developing Hydraulic Systems for 20 years. Contact Scott

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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.

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

 

Besides pressure, flow rate and pressure drop considerations, there is another important variable to consider when choosing the proper components to optimize your electro-hydraulic system. This variable is the duty cycle of your coils. If your coil is improperly sized, failure can occur, especially when operating a valve at 100% duty cycle. However, by factoring in coil temperature when you design you machine, you will avoid undesired failures such as degraded solenoid valve performance.

Besides pressure, flow rate and pressure drop considerations, there is another important variable to consider when choosing the proper components to optimize your electro-hydraulic system. This variable is the duty cycle of your coils. If your coil is improperly sized, failure can occur, especially when operating a valve at 100% duty cycle. However, by factoring in coil temperature when you design you machine, you will avoid undesired failures such as degraded solenoid valve performance.

First, a quick description of the relationship a coil has with your valve. A coil is copper wire encapsulated in resin. The coil windings create an electromagnetic field when current is applied across the terminals. This electro-magnetic field actuates the valve by moving the push pin to the appropriate location. The percentage of time the coil is energized is called duty cycle (you can learn more here).

Normally, when your hydraulic system is running, your coils are continuously energized, creating many opportunities for them to get hot or overheat if the ambient temperatures are extreme. Pressure Control Valves (TS Series) and Flow Control Valves (PV Series) typically run at 100% duty cycle. Directional Control Valves (SP Series) typically run at less than 50% duty cycle. This is when working with reliable and robust coils has its advantages.  Having more durable coils, like HydraForce’s E-series coils, allows you to push the operating limits of your valves and optimize the performance of your machine, especially if your valve is operating simultaneously at maximum flow and pressure rating.

For example, if a valve is energized only a few times during a standard shift of the system, you could use one coil with low nominal voltage (e.g., 10V) and set the supply voltage at 10 to 15% higher (e.g., 12V).  This method allows you to produce more magnetic force for the actuation of the pole tube. Consistently generating a higher magnetic force means that you will have more consistent valve performance (e.g., less hysteresis). In addition, when battery voltage becomes low, or when pressure and flow rates are higher than nominal values, you will see no difference in performance.

According to the first and second Ohm’s Laws, when you increase the duty cycle of the valve, there is more power dissipated through the coil winding. The resistance of the copper is not constant but it is a function of the coil’s temperature.

The change in the resistance of copper due to the change in temperature can be determined by using the following equation:

RF = R20[1 + 0.00393(TF –20)]
where:
R20 = resistance of the coil winding at 20°C (Ω)
0.00393 = Physical constant of copper representing the change in resistance due to the temperaturechange in temperature
TF = coil winding temperature in °C
RF = resistance at the coil winding temperature (Ω)

For example, assume that a 10V, 10-size E-Coil is energized for 1 hour
at 100% Duty Cycle:
R20 = 4.8Ω at 20°C
VSUPPLY = 12V (power supply)
Ambient temperaure of 20°C

Under these conditions, the coil surface temperature and current (amp) values would be:
TS = 64°C; I = 1.8 amps


Applying the first of Ohm's Laws, we can evaluate the resistance
of the coil winding (RF) in that condition:
RF = VSUPPLY/I = 12/1.8 = 6.67Ω

Using the equation
RF = R20[1 + 0.00393(TF –20)]
we can calculate the coil winding temperature inside the core of the coil:
6.67Ω = 4.8Ω[1 + 0.00393(TF –20)]
so, TF = 120°C

Looking at the diagram above, you can see that the temperature inside the coil winding is higher than the temperature on the coil surface, and much higher than the ambient temperature. Therefore, we can expect the following correlation to be true:

The temperature inside the core of the coil is generally greater than ambient temperature. Around 5°C / 41° F more for each watt provided to coil.
TF = TAMB + 5(PSUPPLY)

As you now know, coil damage will occur if the temperature of the core is too high for an extended period. By design, HydraForce coils can withstand these adverse conditions and provide a consistent duty cycle of 100%, all while simultaneously applying a power supply voltage greater then the nominal value. Refer to our E-Coil bulletin for more information on coils and the relationship between ambient temperature and voltage supply that you can apply to HydraForce coils.

In Summary:
• The temperature inside the coil increases when coil is energized.
• Temperature increase is a function of the supply voltage and ambient temperature.
• HydraForce coils can withstand high temperature without degradation of the coil.
• If the duty cycle of a valve is below 50%, you can use a lower voltage coil to get more
• magnetic force in all work conditions.
• Higher magnetic force means performance that is more consistent during low voltage
• conditions. Working pressure and flow rate can be higher than nominal values.
• HydraForce Controller’s are designed to compensate for changes in coil resistance.

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About the Author:

Damiano Roberti is an application engineer for HydraForce Hydraulics Ltd., representing the southeast region of Europe. Damiano resides in Modena, Italy. Contact Damiano

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 functionally equivalent manifolds
with different mounting hole arrangements.

Manifold design using the original mounting pattern.

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

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About the Author:

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

Someone recently joked with me that I’ve never created a circuit that didn’t have at least one Logic Valve in it. HydraForce model numbers for these valves begin with the prefixes EP, EPFR and EV. Typically, these valves are piloted-closed, vented-open, or used as pressure compensators or regulators. I use them often because they are versatile, and they have low pressure-rise and pressure-drop characteristics.

On our catalog pages for these valves, we describe them as: “hydraulic directional element, with multifunction potential when used with other directional, pressure, or flow control devices.” Talk about a vague (albeit true) statement. So, to demystify this situation a little, I started to think about all the different ways spool-type logic valves can be used in integrated circuits. I’ve sketched up some generic circuits that show different ways in which we use spool type logic valves:

Someone recently joked with me that I’ve never created a circuit that didn’t have at least one Logic Valve in it. HydraForce model numbers for these valves begin with the prefixes EP, EPFR and EV. Typically, these valves are piloted-closed, vented-open, or used as pressure compensators or regulators. I use them often because they are versatile, and they have low pressure-rise and pressure-drop characteristics.

On our catalog pages for these valves, we describe them as: “hydraulic directional element, with multifunction potential when used with other directional, pressure, or flow control devices.” Talk about a vague (albeit true) statement. So, to demystify this situation a little, I started to think about all the different ways spool-type logic valves can be used in integrated circuits. I’ve sketched up some generic circuits that show different ways in which we use spool type logic valves: