CBS Inc. is expected to announce the purchase of Ideal Toy Corp. on Thursday, a major consolidation in the $5 billion U.S. toy industry, financial sources said today.

The acquisition was approved by CBS' board of directors before the company's annual shareholders meeting here today, but was not announced. Ideal stock was heavily traded on the New York Stock Exchange this morning before trading was stopped just after 1 p.m. It closed at 12 3/4, up 1 3/8 a share, a gain of more than 12 percent.

It would cost CBS more than $43 million to acquire all of the 3.86 million outstanding shares of Ideal, which had sales of $160 million last year.

CBS President Thomas H. Wyman said in an interview after the shareholders meeting that CBS is considering "a couple of acquisitions" soon. He would not elaborate.

The acquisition would mark part of a major expansion of the CBS/Columbia Group, the CBS subsidiary that includes the company's toy ventures. Gabriel Industries, the CBS toy company, announced only yesterday that it had signed a licensing agreement with Bally Manufacturing Corp. to build and market Bally home video and computer games.

Also in the interview, Wyman said CBS does not expect to seek cable franchise awards again this year, although the company had sought Federal Communications Commission approval in 1981 to do so. Recently, the company failed to win a franchise in Alameda, Calif.

Instead, Wyman said the company would focus its cable ownership energies on a system it recently purchased in the Dallas area.

In prepared remarks, apparently responding to criticism from Wall Street, Wyman defend CBS' $47 million 1981 development program, one factor in sharp cuts in profits. The company reported profits of $163.8 million last year, down from $189.7 million in 1980, cutting per-share profits by close to $1 a share.

In 1980, the company spent $12.4 million for development, up sharply from $3.1 million in 1979. "While this sum is substantially greater than that of previous years, it is not large in terms of corporations our size, in terms of the spending of our competitors, or in terms of the potential awards we see ahead," Wyman said.

Much of the shareholders' meeting was devoted to criticism of CBS news operations by Reed Irvine, a spokesman for Accuracy in Media, who focused on a CBS report blaming retired Army general William Westmoreland for mismanaging the U.S. military effort in Vietnam.

Wyman pledged to meet with Irvine and other concerned shareholders about that program.