Tiny Yet Mighty and Essential Spring Valves

Quality Manufacturing and Proper Materials Impact Performance

Valve springs are a tiny yet mighty component that help prevent failures and maintain smooth operations within engines in both the automotive and marine sectors. To accomplish these tasks, valve springs must be properly designed and constructed. A proper understanding of material selection and compression spring design parameters highlights the key factors that engineers must consider for effective and durable valve spring operation.

The Role of a Valve Spring

Valve springs are positioned around the valve stem and secured by a retainer. Their primary function is to allow fluid flow in one direction, while preventing backflow. These valves are comprised of a body, a valve seat and a spring.

When the forward pressure exceeds the cracking pressure, the valve opens, allowing fluid flow. However, when the pressure equalizes or reverses, the spring force pushes the valve back onto its seat. This blocks the flow from going in the reverse, or wrong direction. A spring valve helps control flow of fluids to protect systems from unwanted backflow.

Valve springs are activated tens of thousands of times per hour, especially in high-end engines. This is a small part that yet remains paramount for a properly functioning engine. Proper material selection, tension and installation make a difference between performance or failure.

No Bouncing or Floating Allowed

An occurrence of “valve bounce” refers to an instance when the valve does not stay seated, or partially reopens. A combination of factors can lead to valve bounce including a weak spring or consistent high-speed operation of the engine where the valve is located.

Valve bounce can lead to valve damage, power loss and worse, catastrophic engine failure. A valve spring constructed of the proper materials with the right amount of tension helps supply proper holding capacity for the valve.

Another malfunction is referred to as valve “float.” The force the spring exerts causes the valve to fully close. A weak spring does not push the valve entirely shut prior to its next opening. When the valves float or don’t close completely, this means a loss of compression that can cause a misfire.

Overall, a properly functioning valve spring protects critical engine components, and also prevents issues with hydraulic lifters by counteracting the oil pressure and restricting lifter movement.

Types of Valve Springs

Valve springs come in various types, each with its own unique advantages.

Conical springs have a smaller upper half, reducing reciprocating mass and increasing the natural frequency.

Ovate wire springs are ideal for higher lifts, distributing weight more effectively.

Beehive springs are suitable for weight reduction and are particularly beneficial for engines operating at high RPM.

And cylindrical valve springs are the most familiar option.

Recognizing Valve Spring Problems

Valve springs, like any mechanical component that experiences significant use, experience wear over time. Factors such as engine speed, operating conditions, and maintenance practices can influence the wear rate.

Periodic inspection of valve springs helps detect signs of wear, such as loss of tension, deformation or fatigue cracks. In addition, regular maintenance, including replacement of worn springs, prevents performance degradation and potential engine damage or worse, catastrophic engine failure.

One simple way is to place a vacuum gauge on the engine and turn the engine on. Rapid changes in the vacuum gauge related to engine speed is a likely indicator that valve springs need to be replaced. Other tips:

  • Checking valve spring pressure: Checking the pressure of valve springs is a critical step for maintaining engine performance. Specialized tools, such as spring pressure testers help accomplish this. These devices measure the force exerted by the spring when it is compressed to a specified length. By comparing the measured pressure with the manufacturer’s specifications, engineers can ensure that the springs are within the desired range, optimizing valve operation and preventing issues such as valve bounce.

  • Calculating required valve spring pressure: Calculating the required valve spring pressure involves considering factors such as valve lift, engine speed and valvetrain mass. By analyzing

    these parameters, engineers can determine the appropriate spring stiffness and pressure needed to prevent valve float, supply valve control and optimize engine performance. Best practices include consulting manufacturer specifications, engineering resources and seeking expert advice to accurately calculate the required valve spring pressure.

  • Valve replacement: Valve spring lifespan depends on several factors, including the engine’s design, operating conditions, maintenance practices and material quality. There is no exact timeframe for valve spring lifespan, however a well-crafted valve spring should last for thousands of hours of engine operation. When detecting signs of wear, valve springs can be replaced to allow for many more hours of engine service.

Designing and Building a High-Quality Spring Valve

Investing in a high-quality valve spring starts with working with a manufacturer that places an emphasis on following proper engineering practices, developing a robust supply chain, and exercising tight control over its manufacturing processes.

CPV Manufacturing follows accepted design practices for valve spring manufacture in terms of:

  • Spring material—this determines the design stress, as a percentage of the minimum tensile stress of the material. This typically is between 35-45%. Considerations for the material include its:
    • Chemical and physical characteristics
    • Elastic modulus
    • Magnetic characteristics
    • Heat treatment of springs
    • Environmental conditions
    • Stress relaxation
    • Corrosion
  • Compression spring design—multiple factors play into spring design including a spring index, spring rate and other parameters such as:
    • Spring diameter
    • Free length
    • Type of ends
    • Number of coils
    • Solid height
    • Direction of coiling
    • Valve spring design parameters such as these, also including cracking pressure, stiffness, wear, and lifespan, directly impact engine performance and reliability. Working with a manufacturer such as CPV, a company with domestic manufacturing facilities and a highly qualified engineering staff, can help with selection of a valve spring that matches the application specifications.

      Optimize your valve train operations and maximize engine efficiency with the proper spring valve for your application. Call CPV Manufacturing today.