Automatic purge of W3 Total Cache via functions.php

Hi there

I would like to automatically purge my cache every hour via a cron job.

I have seen some code to do this via the functions.php:

$w3_plugin_totalcache->flush_all();

Full code is :

// Scheduled Action Hook
function w3_flush_cache( ) {
	$w3_plugin_totalcache->flush_all();
}
 
// Schedule Cron Job Event
function w3tc_cache_flush() {
	if ( ! wp_next_scheduled( 'w3_flush_cache' ) ) {
		wp_schedule_event( current_time( 'timestamp' ), 'daily', 'w3_flush_cache' );
	}
}
add_action( 'wp', 'w3tc_cache_flush' );

This doesn’t seem to work for me – does that need to be instantiated somehow?