Month: May 2014

May 21, 2014

Momentary Switches for Extreme Duty – Reducing Failure Rates.

Momentary Switch Design Parameters

Extreme duty applications that require a momentary switch with potential for extreme temperature ranges or constant operation require more than just switch waterproofing. For more than 40 years CPI’s has made precisely engineered waterproof switches for the Military and Heavy Equipment industries that achieve the most stringent requirements for operation.  By expertly trading off the many conflicting design requirements necessary to achieve an overall goal for MTBF, cost, and electrical parameters, CPI has been able to meet almost any momentary switch operating specification.  Not to mention that our switches are truly “waterproof”, not water-resistant.  You can’t drown our stuff…(-:

Some of the design considerations for our switches include the following:CPI Waterproof Pendant Switches

  1. Operating Temperature Range. CPI has engineered our Pendant switches to avoid contact “freezing” at operating temperatures down to -20F.
  2. Contact travel and pre-travel – These critical parameters affect MTBF directly and must be adjusted to achieve the specified cycle lifetime
  3. Mechanical Endurance – CPI has achieved MTBF of over 1 million cycles rated for high dynamic temperature environments, with careful design of mechanical switch parameters, and new manufacturing techniques for sealing.
  4. Actuator Style – The actuator used for our momentary switch configurations can be specified: either plunger, lever, roller ball, or hand actuated pendant style switches. All with unique engineering challenges to achieve an overall requirement.
  5. Circuit type – Normally Open/Closed and current requirements can be specified for any switch we build, including the challenge of designing for high startup loads.
  6. Mounting & Packaging. CPI provides a wide variety of packaging options with any switch. Each present unique challenges for design and operation.

CPI Momentary Switches For Custom Applications

At CPI our engineering team has made and manufactured custom switches for industrial, aerospace and military environments, for over 40 years. Our partnership with OEM’s goes beyond just design but carries through to the manufacturing and field qualification of our units to achieve all program goals. Based in East Hanover NJ, all our products are designed and manufactured in the USA, and commitment to solving your design problems and manufacturing cost effectively make our value proposition dominant in the industry.

If your switching application demands performance, then you should be demanding CPI.  Contact our headquarters at (973) 887-9400

Or visit our website at http://www.cpi-nj.com

May 21, 2014

Long Stroke Hydraulic Cylinders Part 2 – Replacing Failed Rod-Type Sensors.

Replace rod type magnetostrictive position sensor

Rod based magnetostrictive position sensors are historically one of the primary types of feedback sensors used on hydraulic or pneumatic cylinders where high accuracy was of primary concern.  The sensor (often called an “LDT” or “MLDT”) incorporates a stainless steel tubular probe (ie. “the Rod”) and is surrounded by a short toroidal magnet installed in a counterbore in the piston. Magnetostrictive sensors can consume a fair amount of power and are not the most mechanically rugged sensor technology.  They are subject to shock and vibration issues, and present challenges for installation and field replacement.

The CPI SL series picks up where traditional magnetostrictive sensors leave off.  The sensor technology is completely non-contacting, and is a drop-in replacement for existing rod-type sensors in long stroke applications. No core drilling of the piston rod is required at all. This sensor installation video below documents just how easy it is to replace a rod type sensor in our applications. It can be done in essentially three steps:

  1. Unscrew the existing Rod Sensor from the sensor port and remove the rod.
  2. Insert our patented self locking cable connector using our special slotted hex wrench. The sensor port is typically 18mm or a #8 SAE O ring port.
  3. Fasten the high pressure hydraulic hose to the sensor port with a standard 7/8″ wrench.
  4. Done.

CPI’s LVDT based Linear Position Sensors

CPI’s hydraulic sensor solution is a game changer for position sensing in mobile hydraulics and long stroke piston accumulators.  Other advantages include:

  1. A completely non-contacting measurement technology.
  2. One part for all stroke lengths.
  3. Can be used in telescoping cylinders and piston accumulators.
  4. Field retrofittable for rod-type sensors with no modifications.
  5. Robust to shock & vibration where rod-type sensors do not survive.
  6. Will operate in high temperatures (300F) where rod-type sensors do not.

External Hydraulic Cylinder Position Sensor Mounting

To make the entire assembly work perfectly for external mount simply add an external Linear Position Sensor for Long Stroke Hydraulicscable guide.  With this addition the entire assembly works perfectly for typical mobile cylinder applications like a backhoe loader stick cylinder.  See the illustration.

These components also excel at sensing piston position in hydraulic piston accumulators and do not require extensive design modifications.  They can be mounted on either the gas or the oil side.

About CPI

CPI is a US based manufacturer of precision waterproof switches, electro-mechancial thermal switches and linear position sensors. Heavy duty materials and robust performance characterize all of CPI’s products. Custom designed and off the shelf products in each category satisfy the most demanding operational environments. Industries served include Military, Aviation, Oil & Gas Exploration, Mining, Safety, and Construction Vehicle manufacturers as well as dozens of others.

Visit us at http://www.cpi-nj.com

May 21, 2014

Momentary Switch Technology – For Extreme Environments

ImageWaterproof Momentary Switch Technology

For extreme duty applications a mechanically activated momentary switch is often a critically necessary electronic component, and can also be a primary operational failure point. CPI’s line of Waterproof Momentary switches have been staying dry and operational for over 40 years in the harshest operating environments imaginable through a combination of precise engineering, high quality manufacturing, and robust field testing in the application.

What’s so hard about waterproofing a momentary switch?

Glad you asked. And you’re right to some degree, just seal the switch in rubber, let the contact wires out and we’re good to go right?

That is until you look at the environmental operating requirements of something like a heavy duty construction crane, or oil rig blowout preventer. In these applications design considerations for a momentary switch go beyond just being waterproof. The hazards in these environments include the following:

  1. Contact contamination due to salt, dust, condensation etc.
  2. Contact chatter immunity in high vibration environments.
  3. Switch failure due to heavy electrical load and impulse (startup) loads.
  4. Cold temperature operation and response time.
  5. MTBF of over 1 million mechanical cycles.

Many of these requirements work against one another in the overall design, not to mention that any good final design has to be manufactured for as low a cost as possible.

CPI’s solution to Robust Momentary Switch Design Considerations.

CPI offers cost effective Santoprene sealed switching solutions to a wide variety of waterproof momentary switch design applications. In these designs, parameters such as pre-travel, over-travel, actuation and contact type, and MTBF can be specified. Our thermoplastic santoprene sealing process creates an industrial grade configuration that is truly waterproof, not just water resistant. These products meet IP68 and are UL available.

For our military and other specialty applications, CPI offers momentary contact waterproof switches sealed in Neoprene rubber with full MIL-C ratings for temperature operation down to -65 degrees Farenheit. (MS39058)

And all switch types benefit from a wide variety of mounting configurations from “v-back” for easy mounting on pipes and tubes, to a variety of bracket and panel mounting options.

Momentary Switch Types

CPI manufactures momentary switches in a number of form factors including plunger switches, pendant switches. For a full overview of our product line see our CPI momentary switch product page on our website at http://www.cpi-nj.com

May 3rd, 2014

By Mac Stuhler

Vice President, Control Products Inc.