Achieving small sizes for brush motors and reducing their cost

Frequent Issues

Is it possible to implement both noise countermeasures and surge countermeasures together in small design spaces?

Intra-EMC (self-poisoning)

In recent days, electronic technology has been incorporated more and more into automobile design, the use of radio frequencies has also become more widespread; many intra-EMC (self-poisoning) (*1) problems caused by noise have surfaced.
In addition to noise countermeasures, there is no small number of cases where surge (inrush current) countermeasures are necessary. The number of units incorporated into power supply circuits has also been increasing, and the design space available to accommodate the various parts has continued to shrink.
Even company G has been going through a trial-and-error process in its design endeavors to ensure that its brush motors comply with EMI regulations and satisfy the need to minimize surges.

(※1) In this context, this term refers to the malfunctioning of a particular object as a result of noise emanating from that object.

-Example Case : Company G-
It is necessary to find a way to implement both noise countermeasures and surge countermeasures.

Noise has been countered, but surges have arisen so we want to insert some varistors.

Company G was trying to determine whether capacitors could be used as noise countermeasures.
However, problems still remained in incorporating varistors, and varistors could not be inserted as additional components alongside ceramic capacitors.

Due to the advances made in conserving more and more space and the reductions made in the cost of the materials for the enclosures, no margin was provided in the design so there was no space for varistors to be inserted. If changes were made in the design itself, it would have been necessary to change the enclosures (molds), but the design deadline was approaching, and the company was at a loss because time was running out. At a time when the salespeople were pressing hard for costs to be reduced, there was no budget for changing the molds.

There’s just no space to insert the varistors; nor can a budget be appropriated to change the molds.

On the other hand, whether the molds were changed or not, when the number of components used is increased, problems with increases in mounting costs and control costs also arise.
Unless the current design could be satisfied in budgetary and timeframe terms, the opportunity of doing large-scale business that would become a pillar of future sales would be lost.
At a total loss, company G consulted with Murata Manufacturing, which has extensive experience in circuit protection components and noise countermeasures and has many series of its own leaded components.
After discussions on how both circuit protection and noise countermeasures could be implemented together, company G received some suggestions for parts that would satisfy its needs—problem solved.

Points of Issue

  • POINT1
    We want to use ceramic capacitors and varistors, but there’s just no space to insert these two components.
  • POINT2
    We have neither the time nor the funds for changing the housing (die) as a result of making design changes.
  • POINT3
    We want to avoid any increases in the mounting costs and control costs that will result from using more components.
The Solution

On to cases of introducing components into confined spaces to successfully implementing both noise countermeasures and surge countermeasures together